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[1‘4” ‘11.! . .V m » lily/IIILIIIIIII/Ill/ :‘zv-w- This is to certify that the dissertation entitled Assessment of Thermal Response of Subjects Nearing Functionally Designed Protective Clothing presented by Donna Hahn Branson has been accepted towards fulfillment of the requirements for Ph.D. degreein Family Ecology Date April 26, 1982 MS U is an Affirmative Action/Equal Opportunity Institution 0-12771 III/IllIII/IIIll/III!III/IIIIIIIIIIl/III 293 10432 6438 RETURNING MATERIALS: bV1ESI.} Place in book drop to LIBRARIES remove this checkout from a your record. FINES will be charged if book is returned after the date stamped below. 9-": x 02 . m “Lo-“'03? 3’00 A 18 9 EB 1043999 : Wings-wau ' V @43qu «HWfUG 24 2004 W? W AUG 132005 m§227figgy p ~ a s - ‘ 2 “m“... 3 mm: . “@1219!!! too 0107 A .lol M ASSESSMENT OF THERMAL RESPONSE OF SUBJECTS WEARING FUNCTIONALLY DESIGNED PROTECTIVE CLOTHING By Donna Hahn Branson A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Family Ecology 1982 Copyright by DONNA HAHN BRANSON 1982 6U 787/ ABSTRACT ASSESSMENT OF THERMAL RESPONSE OF SUBJECTS NEARING FUNCTIONALLY DESIGNED PROTECTIVE CLOTHING By Donna Hahn Branson The objective of this research was to assess and compare the perception of thermal comfort and sensation and the accompanying physiological responses associated with selected fabrics and designs, under controlled environmental conditions, simulating Michigan summer weather conditions. This study, conducted at the Institute for Envi— ronmental Research, Kansas State University, was one component of a major research project aimed at developing functionally designed pro- tective clothing for pesticide applicators that offered thermal com- fort and social acceptability. Three fabrics, whose resistance to pesticide penetration was known, were chosen. A spun-bonded olefin and a nylon three-layer laminate served as the protective fabrics. A cotton chambray was chosen to reflect what is commonly worn by applicators. Three designs were specified, two coverall variations and a shirt-and-jeans combi- nation. The dependent variables included: weighted skin temperature, rectal temperature, percentage of evaporated sweat, and thermal com- fort and sensation votes. Donna Hahn Branson A 3 x 3 complete factorial experimental design with six replica- tions was used. Fifty-four male Kansas State University students served as test subjects. Each wore one test garment for one two-hour test session. An activity level of three mets was maintained. Data analysis involved first an examination of the dependent measures by fabric and design over time and second, hypothesis testing. Since thermal-comfort assessment includes physical and perceptual measures as related aspects of a single response, multivariate statis- tical analysis was used to analyze the dependent measures as a whole. Examination of the graphs for the three fabrics showed a consis- tent trend. Subjects wearing the spun-bonded olefin garments exhibited higher temperature readings and greater thermal dissatisfaction than subjects in the other two test fabrics. Thus, one of the protective fabrics offered a comfort level similar to chambray. The MANOVA analy- sis indicated a statistically significant difference for fabric at the .OOOl level. The graphs of the dependent measures for design showed an incon- sistent pattern. There was a tendency for higher physical and per- ceptual measures for the coverall with the ventilating panel. The MANOVA results for design were not statistically significant. Dedicated to Michael, Mike, Renée, and Kerry ii ACKNOWLEDGMENTS The undertaking of a doctoral program and research investigation represents a considerable expenditure of effort, time, and expense not only for the doctoral candidate but also for many others. I have been fortunate in receiving support and guidance from numerous indi- viduals, and it is with pleasure that I would like to express my gratitude to them. Sincere appreciation is extended to members of my guidance committee: To Dr. Jacquelyn Orlando De Jonge, my major professor and director of my dissertation research, for introducing me to the field of func- tional apparel design, for providing the opportunity to participate in a successful major research effort, for providing the opportunity for professional collaboration, and for being a wonderful friend. Dr. De Jonge's ability to foster cooperative interdisciplinary research and to encourage creativity has been an inspiration to me. To Dr. Beatrice Paolucci, for her direction and encouragement throughout my doctoral program and for broadening my perspectives. To Dr. M. Suzanne Sontag, for her aid in focusing my conceptuali- zation and for being a source of encouragement throughout my program of study. To [ha Barbara Stowe, for her encouragement and trust in extend- ing guidance in the early part of my program. iii To Dr. Jane Dyer, for her interest and support. To Dr. Howard Tietelbaum, for his support and advice regarding the experimental design and the use of multivariate analysis, which was always cheerfully given. In addition to my committee, I would like to express my apprecia- tion to two other Michigan State University faculty members, Drs. George Ayers and Ann Slocum, who have had a significant impact on my profes- sional development. They have both strongly influenced my thinking. Gratitude is also extended to Drs. Fred Rohles, Deanna Munson, and Stephen Konz; the staff at the Institute for Environmental Research at Kansas State University; and the student assistants. Their invalu- able expertise and assistance in conducting this research are appre- ciated. The cooperation of the Department of Clothing, Textiles, and Interior Design, Kansas State University, in making their research laundry facilities available is gratefully acknowledged. I also wish to express my appreciation to the Michigan State University Agricultural Experiment Station and the North Central Region Pesticide Impact Assessment Program for their financial support of this research and researcher. A thank-you is also extended to w. L. Gore and Associates and to E. I. Du Pont de Nemours and Co. for providing test fabrics for this study. I also appreciated Sue Cooley's typing expertise and cheerful demeanor as I kept making "final" corrections. To my parents, Arthur and Mary Lea Hahn, I am grateful for your constant love, enthusiasm, encouragement, and prayers. Your courage and your dedication to each other and your children is a source of iv pride and inspiration to me. I also thank my sisters and brothers; their sense of humor and understanding have meant so much to me. My greatest debt in the final analysis is to my family. They have not only managed with a part-time wife and mother, but have grown with me and shared both my successes and frustrations. They have made this possible; it belongs to all of us. I am indebted to our son, Mike, who conscientiously developed the photographs for this manuscript; to our daughter Renee, who assisted in the preparation of the bibliography; and to our daughter Kerry, for being my sunshine. Last, I want to express my heartfelt appreciation and love to my husband, Dr. Michael Branson. His statistics and computer-programming expertise, which was generously given, was truly appreciated. With- out Mike's understanding, patience, and willingness to assume added household responsibilities, this doctoral program would not have reached completion. TABLE OF CONTENTS LIST OF TABLES ......................... LIST OF FIGURES ......................... INTRODUCTION ...................... Adverse Health Effects ................ Patterns of Use .................... Population at Risk .................. Mechanisms of Pesticide Entry ............. Strategies for Minimizing Occupational Exposure . . . . Elimination of Toxic Pesticides ........... Maintenance of a Safe Work Environment ....... Human-Constructed Environment ............ Functionally Designed Protective Clothing ....... Functional Design Methodology ............ Operational Design Process ............. Conceptual Framework ................. Human Environed Unit ................ Human—Constructed Environment ............ Natural Environment ................. Human Behavioral Environment ............ Interaction ..................... Thermal-Analysis Study ............... Statement of the Problem ............... Objectives ..................... Hypotheses ...................... Hypotheses for Research Objective 1 ......... Hypotheses for Research Objective 2 ......... Hypotheses for Research Objective 3 ......... Hypotheses for Research Objective 4 ......... Summary ........................ REVIEW OF LITERATURE .................. Physics of Heat Exchange ............... Conduction ..................... Convection ..................... Radiation ...................... Evaporation ..................... vi Page xi Thermal Response to a Hot Environment ......... Receptors ...................... Central Nervous System (CNS) Integration Sites . . Effectors ...................... Metabolism ..................... Cardiovascular and Peripheral Vascular Control . . Sweat Gland Activity ................ Long-Term Response to Heat ............. Body Temperature .................. Summary ....................... Thermal Sensation, Thermal Comfort .......... Thermal Environment ................. Affective Mental Process .............. Ecosystem Complex .................. Assessment of Thermal Comfort and Thermal Sensation . . Historical Development ............... Assessment Techniques ................ Fabric Properties ................... Garment Properties .................. Summary ........................ III. METHODOLOGY ....................... Controlled Variables ................. Human Environed Unit ................ Human-Constructed Environment--Level 2 ....... Dry-Bulb Air Temperature .............. Mean Radiant Temperature .............. Relative Humidity .................. Air Movement .................... Human Behavioral Environment ............ Research Design .................... Independent Variables ................ Dependent Measures ................. Experimental Design ................. Sample ....................... Facilities and Equipment .............. Procedure for Obtaining Subjects .......... Test Protocol ..................... Pilot Study ..................... Pre-test Protocol .................. Orientation ..................... Dressing of Test Subjects .............. Skin Temperature Thermistors ............ Test Chamber .................... Procedure Following the Chamber Test ........ Laundry Procedures ................. vii Data Treatment .................... 111 Phase l ....................... 112 Phase 2 ....................... 114 Summary ........................ 116 IV. FINDINGS AND DISCUSSION ................. 119 Phase 1 ........................ 120 Fabric ....................... 121 Design ....................... 144 Summary ....................... 166 Phase 2 ........................ l67 Thermal Sensation Votes ............... 168 Percentage of Evaporated Sweat ........... 170 Rectal and Weighted Skin Temperatures, Thermal Comfort Responses ................. 174 Summary Questions .................. 181 Summary ....................... 187 V. SUMMARY AND CONCLUSIONS ................. 193 Summary ........................ 193 Dependent Variables ................. 195 Independent Variables ................ 195 Controlled Variables ................ 196 Experimental Design and Sample ........... 198 Test Protocol .................... 198 Findings ...................... 2OO Limitations of the Study ............... 204 Implications ..................... 205 Design Specifications ................ 207 Laundering and Decontamination ........... 209 Familial Exposure .................. 210 Recommendations for Future Research .......... 211 APPENDICES ........................... 214 A. FORMS USED IN THE PROCEDURE FOLLOWED FOR OBTAINING SUBJECTS .................. 215 B. FORMS USED DURING THE CONDUCT OF THE EXPERIMENT ..... 225 C. EXAMINATION OF TEMPERATURE DATA ............. 233 BIBLIOGRAPHY .......................... 236 viii Table 10. 11. 12. 13. 14. 15. 16. 17. LIST OF TABLES "Own" Clothing Characteristics of Pesticide Citrus Grove Applicators and Mixers, Orange County, Florida, 1978 Energy Costs for Various Activities ............ The Ecosystem Complex: An Organization of Variables for the Study of Thermal Comfort, Developed by Rohles (1971) ......................... The Bedford and ASHRAE Thermal Comfort Rating Scales Controlled Variables for the Human Environed Unit ..... Controlled Environmental Variables ............ Summary of Results of Guthiod:)Penetration Study, Conducted by Orlando, Branson, Ayers, and Leavitt (1981). Summary of the Independent Variables, Fabric and Design . Physical Characteristics of Test Fabrics ......... Number of Test Subjects Per Test Session ......... Specification of Laundry Variables for Three Clothing Groups ......................... Frequency of the Sixth Thermal Sensation Votes by Fabric Frequency of the Sixth Thermal Sensation Votes by Design Mean Clothing Weight Change in Grams for Fabric and Design ......................... Mean Percentage Evaporated Sweat by Fabric and Design . . . Observed Cell Means and Combined Means for Weighted Skin Temperature ....................... Observed Cell Means and Combined Means for Rectal ._ Temperature ..................... ”. . ix Page 14 43 53 58 72 73 85 87 88 96 111 169 169 172 173 177 177 20. 21. 22. 23. 24. 25. 26. 27. Observed Cell Means and Combined Means for Thermal Comfort Responses ................... Cell Standard Deviations for Rectal Temperature, Mean Skin Temperature, and Thermal Comfort ......... Summary of Analysis of Variance for Thermal-Analysis Study ......................... Confidence Intervals for the Difference in Effect of Fabric 1 and Fabric 3 ................. Cross-Tabulation for Anticipated Comfort by Fabric Cross-Tabulation for Anticipated Comfort by Design Cross-Tabulation for Willingness to Wear Protective Clothing by Fabric .................. Cross-Tabulation for Willingness to Wear Protective Clothing by Design .................. Summary Table of Results of Inferential Statistics Summary of Controlled Environmental Variables ...... Page 178 178 179 181 182 183 185 186 189 197 Figure 1. LIST OF FIGURES Spectrum of Pesticide Exposure and Some Related Health Effects .................... Occupationally Related Pesticide-Exposure Illnesses in California During 1978 .............. Functional Clothing Design Process and Strategy Selection ...................... Activity/Information Interaction Flow Process for the Development of Functionally Designed Protective Clothing for the Agricultural Worker ......... Preparatory Activity/Information Interaction Flow Process for the Thermal Analysis ........... The Human Ecosystem .................. Human Thermoregulatory Response to a Warm Environment Experimental Model for the Thermal—Analysis Study District Definition Map of Michigan's Fruit Industry . . Inputs to the Choice of Levels for Fabric and Design . . Two-Piece Design, Design 1 ............... One—Piece Coverall Design, Design 2 .......... One-Piece Coverall Design, Design 3 .......... Inside Ventilating Panel for Design 3 ......... Location of Three Skin Temperature Thermistors ..... Thermal Comfort Ballot ................. Thermal Sensation Ballot ................ Research Design of Thermal-Analysis Study ....... xi Page 20 22 25 27 48 71 74 77 79 80 82 83 90 91 91 95 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. Test Subjects and Equipment in the Sheror Environmental Chamber ....................... Placement of Skin Thermistor on the Right Pectoral Region of the Chest ................. Subject Recording Heart Rate on the Thermal Sensation Ballot ........................ Weighted Mean Skin Temperature for Fabric 3 ....... Weighted Mean Skin Temperature for Fabric 2 ....... Weighted Mean Skin Temperature for Fabric 1 ....... Lower Arm Mean Skin Temperature for Fabric 3 ....... Lower Arm Mean Skin Temperature for Fabric 2 ....... Lower Arm Mean Skin Temperature for Fabric 1 ....... Lower Leg Mean Skin Temperature for Fabric 3 ....... Lower Leg Mean Skin Temperature for Fabric 2 ....... Lower Leg Mean Skin Temperature for Fabric 1 ....... Mean Chest Skin Temperature for Fabric 3 ......... Mean Chest Skin Temperature for Fabric 2 ......... Mean Chest Skin Temperature for Fabric 1 ......... Mean Rectal Temperature for Fabric 3 ........... Mean Rectal Temperature for Fabric 2 ........... Mean Rectal Temperature for Fabric 1 ........... Mean Thermal Comfort Response for Fabric ......... Mean Weighted Skin Temperature for Design 1, the Two- Piece Jeans Assembly .................. Mean Weighted Skin Temperature for Design 2, the Coverall ........................ Mean Weighted Skin Temperature for Design 3, the Ventsuit ........................ xii Page 124 127 128 129 131 132 133 135 136 137 140 141 142 143 145 147 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. Mean Arm Skin Temperature for Design 1, the Two- Piece Jeans Assembly ................. Mean Arm Skin Temperature for Design 2, the Coverall . . Mean Arm Skin Temperature for Design 3, the Ventsuit . . Mean Leg Skin Temperature for Design 1, the Two- Piece Jeans Assembly ................. Mean Leg Skin Temperature for Design 2, the Coverall . . Mean Leg Skin Temperature for Design 3, the Ventsuit . . Mean Chest Skin Temperature for Design 1, the Two- Piece Jeans Assembly ................. Mean Chest Skin Temperature for Design 2, the Coverall . Mean Chest Skin Temperature for Design 3, the Ventsuit . Mean Rectal Temperature for Design 1, the Two-Piece Jeans Assembly .................... Mean Rectal Temperature for Design 2, the Coverall . . Mean Rectal Temperature for Design 3, the Ventsuit . . . Mean Thermal Comfort Vote by Design .......... Number of Subjects Voting Hot or Very Hot by Fabric Over Time ...................... Number of Subjects Voting Hot or Very Hot by Design Over Time ...................... Diagram of the Skin, the HCE], and the Direction of Heat and Moisture Transfer .............. Diagram of Moist Panel Clinging to Skin ........ xiii Page 148 149 150 152 153 154 156 157 158 160 161 162 163 164 165 171 201 CHAPTER I INTRODUCTION U.S. farmers and foresters, in an effort to control detrimental insects, plant diseases, weeds, and crop infestations, have increased their usage of pesticides (Boraiko, 1980). The Mediterranean fruit fly infestation in California is a dramatic example of the serious problem of pest control, a problem which has commanded international attention. In addition to damaging crops, pests can carry serious diseases. In Michigan, health officials are weighing the risks and benefits of instituting a limited pesticide spray program to reduce the mosquito population in areas in which cases of Eastern Equine Encephalitis have been confirmed in horses (Lane, 1981). Although the risk of getting the disease is low for humans, a young Michigan boy who contracted the illness last summer and remains in a coma clearly shows the devastating results. The detrimental effects of pesticide usage, including possible ecological consequences and pesticide-related illness and death, are a persistent concern for many. The contamination of rivers, ponds, and lakes by synthetic compounds continues to be a subject of inquiry for the scientific community and the general public. Also, the increased resistance of insects to pesticides has caused many to fear that we may be breeding ”superbugs." Boraiko (1980) noted that over 400 species of insects and mites are now resistant to pesticides. Besides the negative environmental consequences, reports of adverse health effects associated with pesticides continue to proliferate. Viet Nam veterans exposed to Agent Orange, a controversial defoliant, are a particularly vocal group who have demanded recognition of the hazardous health side-effects of the chemical and compensation for the pain and suffering this exposure has cost them and their families. They hold Agent Orange responsible for causing a variety of health problems, ranging from skin diseases, hearing loss, and cancer to birth defects in their children. Despite these negative consequences, the careful, prudent use of pesticides is considered by many scientists, not only beneficial to society (Kilgore & Akesson, 1980) but also necessary to provide suf— ficient food and fiber for the world's steadily expanding population. After researching the pesticide controversy for over a year, the editor of National Geographic (cited in Boraiko, 1980) concluded: With a steadily expanding population and a decrease in arable land, the world must use pesticides to maintain high crop yields and affordable food. At the moment there is simply no other way to farm on the scale required. Answers to questions of environmental danger, sensible regulation with diligent enforce— ment, proper application, and acceptable chemicals thus are a world necessity. (p. 145) Assuming continued reliance on pesticides, then the potential adverse health effects of workers occupationally exposed to pesti— cides is one area of concern that should be addressed. Documentation of pesticide-related health effects, patterns of pesticide usage, population at risk, and mechanism of transference to the body are presented as a prelude to examining strategies for minimizing worker .. . .uwi‘glan°-“ exposure to pesticides. Further examination of one strategy concludes the chapter. Adverse Health Effects The adverse health effects can be either sudden and of rela- tively short duration, or they may be delayed long-term effects such as sterility, cancer, and neurological and renal disorders. Atten- tion has centered on the dramatic sudden ill effects requiring medical attention of large numbers of field workers (Kahn, 1976a). For example, in September 1976, 118 workers from a 120-person grape-picking crew became ill after entering a field recently treated with dialifor. It was concluded that excessive skin exposure had resulted (Knaak, Peoples, Jackson, Fredrickson, Enos, Maddy, Bailey, Dfisch, Gunther, & Winterlin, 1978). Recently, however, the long-term health signifi— cance of chronic exposure has become an increasing concern. Morgan (1980) warned that proving long-term effects such as increased preva— lence rates of cancer is very difficult and may be impossible. Figurel illustrates both the spectrum of pesticide exposure and the related health effects. Patterns of Use Over the past decade, our pattern of use of pesticides has shifted away from the more persistent pesticides (DDT for example) to the shorter-acting but more toxic organophosphate and, to some extent, carbamate compounds (Freed, Davis, Peters, & Parveen, 1980). Because these compounds are less persistent in the environment, more frequent applications are required in order to maintain pest control, thus necessitating greater applicator exposure. 'Acute exposures Systemic Populations at special risk: (poisoning) pesticide workers. applicators, and topical pickers. domestic population (eyes and skin) Chronic exposure (high-occupational) Leptd phos: . ,. Kepone: delayed ln- Others: Populations at special risk: neuro- neuro- DBCP: organic cancer, manufacturersJomiulaton, logical toxi- ster- arsenic: birth applicators ‘ and beha- city “in! cancer defects. etc. Chronic exposure rgano-chlorines, Alkyl-phosphates: ( low-incidental) halogenated DEP, DMP, ammo-phosphates DMTP, DETP Phenol Metals Tlssues useful for monitoring exposure Adipose. Urine Urine Hair. blood, serum, urine, urine serum Figure l.—-Spectrum of pesticide exposure and some related health effects. (From Davis, Freed, Enos, Barquet, Morgade, & Danauskas, 1980, p. 10. Reprinted with permission of the editors of Residue Review.) Population at Risk The epidemiological history of authenticated episodes of pesti- cide poisonings has shown the population at risk to be those indi- viduals involved in the manufacture (Kiraly, Szentesi, Ruzicska, & Czeize, 1979; Taylor, Selhorst, Houff, & Martinez, 1978), formulation (Glass, Lyness, Mengle, Powell, & Kahn, 1979; Young, Jung, & Ayer, 1979), mixing and loading (Bension, Richter, Weisenberg, Schoenberg, & Luria, 1979), and application (Bension et al., 1979; Hayes, Wise, & Seir, 1980) of pesticides as well as those involved in harvesting operations (Burns & Parker, 1975; Knaak et al., 1978; Wicker, Williams, Bradley, & Guthrie, 1979; Wolfe, Armstrong, Staiff, Comer, & Durham, 1975). These categories should not be considered mutually exclusive. The California Department of Public Health has monitored the acute effects on California workers of pesticide exposure, and concluded that "occupational disease caused by pesticides and other agricul- tural chemicals is one of the most important occupational health prob- lems in the State" (Kilgore & Akesson, 1980, p. 25). Figure 2 presents data gathered by this reporting service by category of worker for 1978. 180 160 140 Number ol human pesticide exposure illnesses Ki 0 Figure 2.—-0ccupationa11y related pesticide-exposure illnesses in California during 1978. (From Kilgore & Akesson, 1980, p. 26. Reprinted with permission of the editors of Residue Review.) Figure 2 clearly demonstrates that ground applicators, that is, those who apply pesticides using a variety of spray and dusting equipment, received medical treatment a greater number of instances than any other population at risk. It should be noted that even though California has an extensive medical reporting system, some investigators (Kahn, 1976a) believe that the number of reported cases represents only a small fraction of the true incidence of pesticide poisonings. The concern that the number of documented cases may be grossly underestimating the true scope of the problem has been primarily focused on the population of field workers. California alone has more than 300,000 farm workers, including housewives and students, plus an unknown number of illegal aliens (Kahn, 1976a). Social and economic pressures, language barriers, and risk of deportation undoubtedly prevent many pesticide-related illnesses from being reported to physicians (Kahn, 1976a). Kahn (1976a) pointed out that "the agricultural work forces in Arizona and Texas share many of the same characteristics . . . , the ethnic make-up and sociological details may be different, but the net effect is very similar" (p. 694). Thus, Kahn (1976a) emphasized that this problem is not limited only to California. A second factor that prompts researchers to suggest that the number of pesticide poisonings is greater than the number of documented cases is the nature of the early symptoms. Nausea, headaches, diar- rhea, skin rash, and blurred vision can be symptomatic of other ill- nesses, making recognition of their occupational origin more difficult to ascertain for worker and physician. The issue of the secondary exposure of the workers' family has received little attention, although documented cases have been reported in the literature. For example, in Virginia, an investigation of over- exposure of workers to chlordecone, an organochlorine insecticide, found detectable levels of chlordecone in the blood of all employees (Taylor et al., 1978). Over half of the workers had a history of tremor which interfered with ordinary manual tasks and daily activities. Despite detectable levels of chlordecone being found in 94% of the workers' family members, serious examination of the cause of secondary contami- nation of family members was not undertaken. The topic of secondary exposure of the family is beyond the scope of this research. There have also been isolated efforts to assess the adverse health effects of pesticides on the general population. The interested reader is referred to Boraiko (1980) and to D'Ercole, Arthur, Cain, & Barrentine (1976) for discussion of this topic. Exposure of the gen- eral public to pesticide hazards is outside the scope of the present research. Mechanisms of Pesticide Entry There are three major routes of entry of pesticides into the human body: oral, respiratory, and dermal. Numerous investigators have established that dermal exposure is the major mechanism for pes- ticide entry (Hansen, Schneider, Olive, & Bates, 1978; Nigg, 1980; Taylor et al., 1978). Durham, Wolfe, & Elliot (1972) compared the dermal and respiratory routes and found that 87% of the total expo- sure was accounted for by dermal exposure. Rate of dermal absorption is a function of the specific compound, use of variowssolvents("Classification of Cutaneous Hazards and Their Effects," 1980), extent of exposed skin area and chnation of contact, anatomic region (Maibach, Feldmann, Milby, & Serat, 1971), and ambient temperature (Hayes, Funchas, & Hartwell, 1964). Strategies for Minimizing Occupational Exposure The range of documented and suspected adverse health effects for an identified population at risk, as well as data on the primary routes of entry of pesticides into the body, suggest a basic mandate: minimize worker contact with toxic substances (Morgan, 1980). Although the wisdom of the mandate is obvious, the means to achieve it are neither simple nor acceptable to all parties involved (Morgan, 1980). Various strategies, some having limited applicability for certain classes of workers, have been suggested in an effort to support the basic mandate. Elimination of Toxic Pesticides The elimination or restricted use of toxic pesticides has been attempted through legislation and standard-setting. Created by President Nixon in December 1970, the Environmental Protection Agency (EPA) was given the administration of the Federal Insecticide, Fungi- cide, and Rodenticide Act (FIFRA, transferred from the U.S. Department of Agriculture) and the responsibility for the registration of pesti- cides. The EPA was also given the duty of establishing pesticide residue tolerances on raw agricultural commodities. In 1972, FIFRA was amended, requiring the EPA to reregister all pesticide products by 1976, over 40,000 products (Doutt, 1979). In order to register a pesticide, the EPA requires both acute and chronic toxicity tests be performed. Chemical industries spend years testing a product to ensure both its safety and its effectiveness. The RPAR process has been developed to investigate products thought to be possibly hazardous to the environment or humans and to assist in the regulatory decision- making process. Quantitation of risk of human pesticide exposure is part of the risk-benefit equation in the decision process (Davis et al., 1980). Doutt (1979), in tracing the history of pesticide regulation, noted that a new national pesticide law became effective in October 1978. Doutt (1978) charged that the law is very solicitous of the pesticide industry. Data on the environmental persistence of a chemical and its full toxic potential must be gathered. Morgan (1980) stated that knowledge should not be limited to only active ingredients, but also to degrada- tion products during storage and following applicationanle)byproducts. Despite a large organized mechanism for examining and register- ing a pesticide, toxic chemicals continue to find their way into the market place. Maintenance of a Safe Work Environment This basic strategy has been implemented in several diverse ways, including monitoring systems and established reentry intervals. Development of a system to monitor the health of employees through preventive medical-supervision programs has been advocated (Culver, 1976). Yet, the mobile nature of the field workers precludes 10 the possibility of monitoring any delayed health effects for this population. Monitoring of the work environment for quantities of toxicants has also been suggested. This might involve the monitor- ing of residue levels in factory and field air, on skin and clothing, on soil, and on foliage in the field (Culver, 1976, p. 125). Both methodological and cost considerations limit the universal applica- bility of this strategy. The establishment of ”reentry intervals," set by the EPA, requires that field workers not enter a treated field for a desig- nated time period, dependent on the specific compound. In addition, California has enacted state regulations more stringent than the fed— eral standards. Both the established reentry periods and the methods used for hazard assessment have come under attack. Many feel that the intervals are unduly harsh (Culver, 1976). The extensive research devoted to the reentry problem (Burns & Parker, 1975; Iwata, Knaak, Spear, & Foster, 1977a, 1977b; Kahn, 1976b; Knaak et al., 1978; Serat, Mengle, Anderson, Kahn, & Bailey, 1975; Spenser, Cliath, Davis, Spear, & Popendorf, 1975) demonstrates the difficulty in establishing reentry intervals that are both safe (for a variety of compounds) and reasonable to agricultural interests. This strategy offers possible protection only to field workers. Thus, maintenance of a safe work environment is not always a feasible alternative, but perhaps a micro-environmental strategy can ultimately provide increased safety and better health for workers occupationally exposed to pesticides. Human-Constructed Environment The rationale behind this strategy is that a micro-environment, a human-constructed environment, could be constructed to serve as a protective interface between the worker and the environment. Enclosed vehicles (i.e., tractors, planes, or helicopters) are frequently used as methods of application. There is evidence to suggest that enclosed vehicles do not offer the level of protection desired. Cohen et a1. (1979) studied Israeli pilots of an aerial spray company which sprays 50% of the pesticides in Israel. They learned that pilots are exposed to pesticides in two stages of their work: the loading phase and in flight, which resulted from flying back into clouds of pesticide aerosols and vapors (Cohen et al., 1979). They found the presence of pesticide concentrations in the cockpits and concluded that the level of concentration was a function of wind conditions. Pesticide concentrations have also been found inside enclosed tractor cabs. Therefore, the quest for a more proximal human-constructed envi- ronment that could provide protection against a hazardous workplace has continued. Because of limitations of each of the strategies, protective clothing, which could be used as a barrier between the worker and the environmental hazard, has commanded increased atten- tion from government, industry, public health officials, and research— ers (Cohen et al., 1979; Davis et al., 1980; Morgan et al., 1980). The recommendation of protective clothing has influenced the RPAR decision on several occasions. Davis et a1. (1980, p. 8) cited 12 the example of chlorobenzilate, which was found to be a weak carcino- gen but was permitted on the market with the stipulation that worker protection be achieved through the wearing of protective clothing. There is a growing tendency to suggest protective clothing as an alternative to banning a "suspicious" compound for which an adequate substitute is unavailable. Protective clothing also offers the advan- tage of being applicable to all of the occupational categories given in Figure 2. While consensus on the need for protective clothing is emerg- ing, agreement on a definition of protective clothing is not so widespread. For example, the Federal Register has defined protective clothing at least three times. On March 11, 1974, protective clothing was defined as: at least a clean hat with a brim, a clean long sleeved shirt and long legged trousers or a coverall type garment, all of closely-woven fabric covering the body, including arms and legs, shoes to entirely cover both feet, clean socks, and clean fingerless gloves covering the back and front of hands and wrists. Two months later, May 10, 1974, the Federal Register redefined pro- tective clothing as "at least a hat or other suitable head covering, a long sleeved shirt and long legged trousers or a coverall type garment." Kahn (1976b) took issue with the EPA as being "unaware that their prescribed 'protective clothing' was actually the usual attire of most workers engaged in foliar contact activities" (p. 39). Hats, long-sleeved shirts, and jeans are worn, Kahn noted, as protection against thorns, twigs, and sunlight. 13 Prior to the March 11, 1974, definitions, the EPA had suggested that protective clothing should be "impermeable.” Cohen et a1. (1979) had likewise specified ”impermeable uniforms, boots and gloves” (p. 85) in their recommendations for Israeli ground crews and pilots. The necessity of protective gear being impermeable to pesticide vapors, dusts, sprays, and even direct spills has dominated the development of available protective garments and equipment. Dispos- able nonwoven fabrics have been used in two-piece and coverall designs, aprons and gloves. The effectiveness of the fabrics as barriers to both particulates and liquids has been documented (Scheinberg, 1979). Davis et a1. (1980) undertook a study designed to compare the effectiveness of commonly worn clothing by the Florida pesticide applicators (Table 1) versus 100% treated and untreated cotton— denim coveralls. Their (Davis et al., 1980) results indicated that 100% cotton denim coveralls offered greater protection than the growers' own clothing. Davis et a1. (1980) recommended the use of 100% cotton overalls for dermal protection. However, sev- eral studies (Ware, Morgan, Estesen, & Cahill, 1975; Wicker et al., 1975) have suggested that in the presence of moisture or high humidity, cotton jeans can be soaked by foliar contact, with a resultant increase in dermal absorption. Rubber rain gear has also been suggested. At the other end of the spectrum, elaborate protective suits, boots, and head gear equipped with an independent air supply and constructed of various fabrics have been developed. Despite the considerable effort expended on the development of protective gear for the agricultural worker, 14 Table 1.--"Own" clothing characteristics of pesticide citrus grove applicators and mixers, Orange County, Florida, 1978. Subject No. Type of Clothing Worn 1 Synthetic, short—sleeve shirts (thin), frequently open. Work pants cotton and/or synthetic. 2 Cotton shirts, sweat shirts, and "T” shirts occa- sionally. Work pants. Low shoes. 3 Primarily a thin, synthetic shirt and trousers. Occasionally synthetic/cotton shirts. Rubber boots. 4 Combinations: "T” shirts and short-sleeve shirts. Variety of work pants, light-weight. 5 Combinations of synthetic short-sleeve shirts (light-weight) and work pants. Low work shoes. 6 Fresh, very clean and pressed long-sleeve cotton shirt daily. Trousers cotton and/or synthetic. Ankle leather boots. 7 Variety of short-sleeve shirts, "T" shirts, and sweat shirts. Work pants varied from cotton twill to cotton synthetic. 8 Short-sleeve, cotton/synthetic shirt worn open. Thin khaki trousers. Low shoes. 9 A varied assortment of shirts, sweat shirts (long 10, 11, 12, 13 and short sleeve), and athletic jerseys. Trousers varied including shorts; sandals. Wore heavy army “fatigue" coveralls of a heavier twill finish than the University of Miami protec- tive clothing. These military green fatigues were from a surplus store (no labeling to determine type and weight of fabric; long sleeve). (From Davis et al., 1980, p. 16. Reprinted with permission of the editors of Residue Review.) 15 what is now available has not been widely accepted by many of the workers at risk. Protective clothing is seen as hot, uncomfortable, and expensive by California field workers and plane loaders (Boraiko, 1980). Data gathered by Henry (1980) indicated that independent farmers considered protective clothing valuable but unacceptably hot for Michigan summers. Culver (1976) concluded that protective garments “impose physiologi— cal stresses that in our work environment are largely unacceptable” (p. 42). Freed et a1. (1980) noted that in temperatures between 28° and 40°C, current protective clothing “that encases a large part of the body would not only be extremely uncomfortable, but would be a hazard in itself due to hyperthermia or heat stroke" (p. 160). And the EPA backed down from its specification of "impermeable” clothing, saying that such clothing could be considered a greater risk, due to heat build-up leading to heat prostration, than not wearing any pro- tective clothing (Federal Register, July 31, 1973). Unfortunately, the currently available protective clothing has not been developed by studying the whole problem. Emphasis has been directed toward finding an impermeable fabric. Consideration for user acceptance has not been explored. Attention has not been focused on the problem of thermal comfort of a worker toiling in a hot environ- ment while wearing an “impermeable" garment. The development of practical protective garments that satisfy the individual's needs of thermal comfort, acceptability, and protection is needed. 16 Functionally Designed Protective Clothing In the fall of 1978, Jacquelyn Orlando De Jonge, Ph.D., then Associate Professor in the Department of Human Environment and Design, Michigan State University, currently Head and Professor of the Depart- ment of Textiles, Mechandising, and Design, University of Tennessee, undertook a research investigation aimed at limiting the dermal exposure of the independent farmer to pesticides, while maintaining acceptable thermal-comfort levels through the development of £339; tionally designed protective garments. The total research effort has been supported by the Michigan State University Agricultural Experiment Station and the North Central and Southern Region Pesticide Impact Assessment Programs. The investigation focused on independent farmers, specifically the fruit—grower population, who ordinarily perform the tasks of mixing, loading, and applying pesticides, as well as being involved in the harvesting of the crop. The method of pesticide application for fruit trees and the frequency of application further enhance the opportunity for deposition of pesticides on the applicator's skin and clothing. Thus, the data previously cited in Figure 2 suggest that the potential exposure to pesticides can be significant, yet the independent farmer has shunned protective clothing, citing the lack of thermal comfort as a primary reason. It is also likely that the inde- pendent grower perceives that protective clothing may become a future requirement and ”thus another infringement upon their private lives‘I (Henry, 1980, p. 21). All of these concerns were systematically 17 addressed in the conduct of each component comprising the total research effort. The present research is one component of the overall research project, with the major thrust being the assessment of thermal com- fort associated with selected fabrics and designs of known protective qualities under controlled environmental conditions. The ultimate purpose of this study was to contribute to the development of func- tionally designed protective garments for the fruit grower. Before proceeding with a formal statement of the problem, however, it is critical to view this research in the context of the larger project and to understand the methodology implicit in this design effort. An overview of first, the functional design process and second, the implementation of the process as it is being used to design protec- tive garments is given to underscore the interrelatedness of the various components and how this quality impacted on the conduct of the thermal-analysis component. Functional Design Methodology The functional design methodology is a systems approach to design which seeks to explore the design situation in a holistic manner. The increasing complexity of design problems has stimulated the development and adoption of a wide variety of design methods, in response to world-wide dissatisfaction with traditional procedures (Jones, 1970). Alexander (1977) commented that today functional problems are becoming less simple all the time, with more design problems reaching insoluble levels of complexity. Accompanying this \éfifiz-#r 18 growing complexity is a vast body of constantly changing information and specialist experience. Although all of this is available for the designer, the information and expertise are so widespread, diffuse, and unorganized and the designer so reticent to reach out for such input, that it is more comfortable to rely on traditional design methods. The design process traditionally used for apparel is one based on the creative inward assimilation of inputs in the designer's head. The design solution emerged as a mysterious output of the designer's brain. Traditional apparel designing emphasized creating an aesthetic- ally pleasing, socially acceptable, and psychologically comforting garment. The physical needs of the body, while not ignored, were certainly not a primary concern. With the advent of space-age travel, increased usage of industrial clothing, and the burgeoning growth of participatory sports, there has been an increased demand for special—purpose clothing. Such clothing must be designed to accom- modate all of the body's needs, and sometimes to protect the indi- vidual from harsh environmental conditions. Clearly, the traditional apparel-design process is inadequate for such design situations. Jones (1970) has examined many of the new design methods and has shown them to be an extension of older methods. In all of the new design methods, the design process has been externalized, with an aim toward making designing more manageable. But the clear, concise elucidation of the design problem, as perceived, can also be readily 19 observed and critiqued by those who are not members of the design team, thus providing another benefit. Figure 3 presents a schema for the functional apparel-design process, as given by Orlando (1979). Jones (1970) characterized the process as being one of divergence, transformation, and convergence. Once the design request has been received, it is treated as a start- ing point for the investigation. Exploring the design situation initiates the divergent search, a process aimed at expanding problem boundaries in many directions, with attention also directed at the consequences. It is a step back, in an attempt to examine the design problem from different perspectives, rather than a plunge ahead with preconceived solutions. This critical step identifies the general objectives and distinguishes user needs and other pertinent require— ments, thus laying the groundwork for the designation of the critical factors. Once the critical factors have been identified, the neces— sary experiments or studies are planned, carried out, and the data are analyzed. This kind of pre-design work can be costly and time consuming. Therefore, asking the right questions and knowing when to terminate the search-acquisition phase is of the utmost importance. Assessment of the findings of each critical factor results in the generation of design specifications. This begins the creative process of transformation. The main objective of this phase is to transform the results of the divergent search into a general pattern, into subsolutions that will later permit convergence to a prototype design. This is the stage where specific objectives, boundaries, constraints, and critical variables are identified. Frequently, the —..L. ‘11- .5V—- 20 .mnm— .ovcm—Lo Eogmv A.Lo;p:m mgu mo :owmmmELma saw: umpcweaom .wfi .a .cowpoonm zmwpmcpm new mmwuoga :mwmwv mcvngFU chowpucsmii.m mesmed :owpomu -m_umm com: amm04m>mo mcwummp mm>h0homm :owumuv$_omam m mwgmumco um:_cmm uwgmwwz mcowus—Om cowumemwu:_ w>wumwgu mowuowczm m=_ELoumcwmca omzmmgmo mzcwccuou oe om>~mumma ucwsmmwmmm xum>wuum manpuzzhm “cosmmwmmm summon; —mo_mo~ommzsn m Eo—noga we :o_am:_mwv :ocmwm :ovuescowcw ammoumxm mwmzpaca owaas zo~e<=efim mwmemcu :omum>gwmao zuumuo mcwELoumcwmga N acmsgoumc_mgn zow>goucw Low: aocwu -mwmcoucw P~=m_> mn_puwnno mpmum — onH<34<>m ownedm>mo amzmmgmHmuzmm ouonmxm mpamzu zwgmmo ma>kopomm wpompoca tmcmwmmu AF—mcowpoczm we pcoEQoFo>wu asp god mmmuoca zon cowpomgwpcw cowpwELowcw\apw>wuueoeoma e F .o. .e . :o—w :ovumecowcw mwumuwccw T mwmwcpcam scrumELowze mmumo+ucw pHHHHV mHm>4 ucwewgmnxw we uuzvcou mwumuevzw Gamma; zofieopmhmzou \zuHmmo ma>»o»oma omNHHHmonA\om¥zgmucH . _ wwwx_ac< copwmcumzm mwmzpwc< _ . . _ . a :owuawocwm :owuomwm . cowummoawo uwcnmd ucwEm>oz ” com: Low: _ _ _ . _ cabana _mo,owao _ Lapsed quepweu .anm»;a . _aowmoFo;uxma-owoom _ 23 Departments of Human Environment and Design, Entomology, and the Pesticide Research Center at Michigan State University was formed to carry out this overall research project. The design and conduct of the various studies shown in Figure 4 were carried out by individual team members or some combination of team members. In addition to the thermal-analysis study completed for the doctoral research, the author participated in the design, conduct, and analysis of the fabric penetration and deposition studies, the formation and ranking of the design specifications, and the development of the prototypes. Follow- ing the departure of Jacquelyn Orlando De Jonge, Ph.D., from Michigan State University, the author assumed a leadership role in the field- exposure study (part of the validation analysis) and the subsequent design modifications. However, only the thermal-analysis study is reported in this work. Initial exploration of the design situation resulted in the decision to examine two major critical factors, that is the socio- psychological and physical factors. This is not to say that other critical factors, such as economic and aesthetic, were ignored. Rather, due to resource constraints, experimental studies would only be planned for what were considered the two most critical factors requiring assessment. Recognizing the importance of the socio-psychological functions of clothing, the pre-design divergence stage began by eliciting infor- mation from Michigan farmers (not necessarily fruit growers). Their preference and patterns of use for work clothing, their views on the potential health hazards of handling pesticides, and their perceptions 24 regarding protective work clothing were some of the topics that were investigated. This was accomplished in two ways. First, a purposive sample was used to explore user reaction to protective clothing regarding fabrics, color, and style preferences. The findings from these interviews provided insights into subsequent work. Henry (1980) then surveyed Michigan farmers to assess their perceptions of the attributes of the proposed protective clothing. Rogers and Shoe- maker's theory (1971) of perceived attributes of innovation provided the conceptual framework for Henry's study. Five hundred farmers responded to Henry's survey, providing data on characteristics of the Michigan agricultural worker and his per- ceptions of the innovation. A further result of the study was the derivation of design specifications. Three of the specifications that had particular import for the thermal—analysis study were: 1. The garment must be perceived by the users as more comfort- able than the protective clothing presently available. 2. The garment must be perceived by the users as meeting their need to be covered and protected from the dangers of pesti- cides. 3. The garment must be perceived by the users as being comfort- able as well as protective. Simultaneously, the movement and protection needs of the farmer were being assessed in two different ways. The movement needs were being investigated through observational techniques. Agricultural work clothing must accommodate the movement needs of the farmer and should not contribute to farm-machinery accidents. A fabric-penetration study was also conducted to evaluate the protective qualities of selected fabrics under controlled laboratory conditions. A r. "M ‘1 gr "ff 25 description of the methodology and the findings are reported in detail elsewhere (Orlando, Branson, Ayers, & Leavitt, 1981). The results of all of these investigations were used as inputs into the planning of the thermal-analysis research. If protective clothing was to be adopted by the independent farmer, then clearly protection and thermal comfort had to be accommodated in the design prototype. The present study, as shown in Figure 5, was undertaken to investigate this issue. User User Fabric | Reaction Perception xgzimETE Penetration f Interviews Analysis y Analysis J l l THERMAL ANALYSIS Figure 5.--Preparatory activity/information interaction flow process for the thermal analysis. Conceptual Framework The study of the influence of fabric and design on thermal com— fort required an analytical framework which permitted the conceptuali- zation of the wholeness, the complexity, and the interdependence between the individual and his/her environments. 26 The human body functions like a heat "engine" continuously transforming food, the body's fuel, into heat, as a furnace converts gas or oil into heat. The heat produced within the body is stored within the body, given up to the environment, or a combination due to a myriad of environmental and individual characteristics. Clothing can be viewed as a person's nearest environment. As such, clothing impacts on the body's ability to exchange heat with the natural envi- ronment, thereby influencing the thermal well-being of an individual. The maintenance of the internal body temperature within a narrow range is critical not only for comfort but also for the proper func- tioning of vital organs. The complexity of the relationship between the tpppl person, his/her tptgl environment, and thermal well-being demanded a framework that could accommodate (1) the conceptualization of the problem, (2) the determination of the segment to be investigated, and (3) the subsequent interpretation of the findings within the broader contexts of the phenomenon. Hanlon (1969) noted that the human ecological perspective offered a framework whereby the needs of mankind-—as individuals, in groups, and as commu- nities--may be approached, not merely in a reductionist fashion . but rather in a holistic manner wherein the integrated responses of man to environmental forces find expression. (p. 57 The human ecological approach, which focuses on human beings interacting with their environment, was used in this study. The organism, its environment, and their interaction are referred to as an ecosystem. Flows of matter, energy, and information continuously take place in the human ecosystem through biological, physical, and 27 social processes. These processes consist of (l) the input from the environment, (2) the transformation or utilization of the input by the organism, and (3) the pptppt_from the system which may or may not be recycled back into the system. Figure 6 presents the human ecosystem model which served as the conceptual framework for this research. The model (Bubolz, Eicher, & Sontag, 1979) depicts the human environed unit (HEU) interacting with the three environments (NE, HCE, and HBE) that provide the resources necessary for life. NATURAL EM! 1 RONMENI SPACE-TIME / PHYSICALHBIOLOGICAL lllH/lll [NV 1 RONED UlllI Blormsmnu—A Socm. Sono- . , Socxo- \ / PHYSICAL uymcu PSYCHOLOGICAL «ll—v SocuocuuunAL illlWl llUflNl BEIlAV IORAL CONSIRUCTED EW 1 ROMENT ENV I ROMENT Figure 6.--The human ecosystem. (From Bubolz et al., 1979, p. 29. Reprinted with permission of the authors.) Human Environed Unit The HEU represents the population of Michigan independent farmers who share the common interests of fruit farming and therefore typically 28 apply various pesticides to their orchards. Based on information gathered by Henry (1980), it was learned that male members of the family are ordinarily responsible for pest control. In addition to this common attribute, the workers all possess biophysical, psycho- logical, and social dimensions. The biophysical dimension includes the body's thermoregulatory system and other bodily systems necessary for life, as well as factors such as age and height and weight char- acteristics. The psychological dimension refers to all those factors, feelings, and sensations composing the psyche. The social dimensions include all those feelings, sensations, and characteristics that involve social interaction. Human-Constructed Environment The human-constructed environment (HCE) is the total environ- ment created by human beings and includes sociocultural, sociophysical, and sociobiological components. The sociocultural component encompasses technology, laws, values, and the formation of social institutions such as economic, political, health, and educational institutions. Thus, the sociocultural com- ponent includes the development of numerous pesticides as well as laws designed to regulate their use because of values placed on the importance of health and safety for the agricultural work force and the general population. The widespread use of pesticides also reflects the social values of ensuring sufficient food and fiber for the world's population. The formation of health systems for monitor- ing the health status of the agricultural work force on a continuing basis has received considerable attention (Culver, 1976). Education 29 programs to train pesticide applicators to meet safety standards set by the EPA are a result of Congressional Order. Since 1976, more than two million private and commercial pesticide applicators have been certified by Cooperative Extension Service state training pro- grams (Sutherland, 1980). The sociophysical component includes constructed objects such as the growers' clothing, the specific pesticides used, and the machinery that is designed for pesticide application. Fruit growers use pesti- cides that can be formulated in such a way that they can be applied as a spray. Wettable powders (WP), consisting of fine pesticide particles, surface-active agents, and inert fillers, and emulsifiable concentrates (EC), composed of an organic solvent and an emulsifier, are the most frequently used formulations for fruit trees. A wide variety of spray equipment can be used, although the air-blast sprayer, a tractor-driven large spray tank fitted with many nozzles, remains the most commonly used device in Michigan. The clothing that is nor- mally worn in Michigan, based on discussions with Cooperative Exten- sion personnel and informal interviews with farmers, appears to be similar to the clothing cited in Table l. Jeans and long-sleeved chambray shirts are a favorite when the weather isn't too warm. The sociophysical component also encompasses a vast array of personal and household artifacts, such as automobiles, furniture, washer and dryer, and carpeting. All of these represent potential mechanisms of pesticide transference from the worker to other family members. If the fruit grower's contaminated clothing and shoes are not removed at the work place, then contamination of the car, home 30 furnishings, and even the family pet can occur. Laundry procedures can also be a vehicle for contamination of family members. Finley (1979) showed that washing clean fabrics with those containing methyl parathion residues resulted in contamination of the clean fabrics. The sociobiological component includes pets, plants, and the alteration of them and humans through exposure to pesticides. Natural Environment The natural environment (NE) includes climatological factors as well as everything else that makes up the natural habitat of Michigan fruit growers. The time dimension is the pesticide spray season, i.e., the spring through the early fall. Human Behavioral Environment The human behavioral environment (HBE) is composed of others, their thoughts, feelings, and actions. For example, the growers' families would be vital components of the HBE. Interaction Interaction can and does take place within the environed unit, between and within each of the environments, and between the environed unit and the three environments. For example, the use of protective clothing may be due to the grower's perception of the need for greater safety, or to the persuasive efforts of family members or friends, or to the effectiveness of educational programs, or to legislation requir- ing such clothing. The reasons for wearing the garment may impact on the way the garment is worn and cared for (for example, laundry procedures), and thus on the minimization of dermal contamination of 31 the grower and his family. In addition to protective qualities, the garment itself will have characteristics, such that when it is worn under typical use conditions (i.e., temperature, relative humidity, and wind velocity), the thermal sensation and comfort of the grower will be affected. If the garment is perceived as being sufficiently hotter (a nebulous quality) than what is normally worn, then the grower will likely reevaluate his willingness to wear protective clothing. Viewing the protective clothing issue from an ecological perspec- tive permitted the conceptualization of the whole, the component parts, and their interactions. This conceptualization gave an over- view of the larger problem, so that pieces of the problem could be isolated for investigation, and the findings subsequently interpreted within the context of the whole. Thermal-Analysis Study The present investigation focused on measuring thermal comfort and sensation of human subjects wearing garments of known protective qualities, under controlled environmental conditions in a laboratory that simulated Michigan summer weather conditions. In assessing thermal comfort and sensation, it is important to distinguish between the perception of comfort and sensation, and the underlying physio- logical dimensions that accompany the affective process. A controlled laboratory setting permitted monitoring vital physiological phenomena in addition to measuring subjective thermal sensations while maintain- ing constant environmental conditions. Recognizing that different kinds of settings impact on behavior (Bronfenbrenner, 1979), still, L...__..._....._z. 32 the advantage of being able to control and monitor vital variables and parameters prompted the researcher to use a laboratory setting. Statement of the Problem Protective clothing has been shown to offer increased resistance to pesticide sprays and dusts and therefore is a viable means of reducing dermal exposure to pesticides. Yet, protective clothing has not been widely adopted by the population at risk, including the Michigan fruitgrower. Many indicate that protective clothing now available is simply too hot. They prefer to wear their normal work clothing. In support of the total research effort to develop functionally designed protective clothing for the Michigan fruit grower while main- taining acceptable thermal comfort levels, this study was undertaken. The over—all purpose of this research was to investigate the percep— tion of thermal comfort and sensation, as well as the underlying physiological phenomena, of fabrics of known protective qualities and designs under controlled environmental conditions, simulating a work environment. Objectives The following objectives motivated the conduct of the experiment: 1. To determine whether subjects who were wearing a specified fabric/design combination differed in their thermal response to a controlled heat stress environment. Thermal response was assessed by the physiological criterion measures of rectal temperature and 33 weighted skin temperature, and the affective criterion measures of thermal comfort and sensation. 2. To investigate if the total volume of sweat secreted by the test subjects and the percentage of sweat which evaporated differed by fabric and design. 3. To determine whether subjects' experienced comfort versus their anticipated comfort differed by fabric or design. 4. To determine whether subjects' willingness to wear protec- tive clothing was influenced by fabric or design. 5. To formulate recommendations for the final protective garment prototype in the form of design specifications. Hypotheses In order to meet objective one, the data were treated in two distinct phases. First, the dependent measures, both physiological and affective measures, were plotted over time for fabric and design. The second phase focused on hypotheses testing. The null hypotheses for research objectives one through four are stated below. Hypotheses for Research Objective 1 H1 - H3: There is no significant difference between fabrics for: 0 0 (1) mean weighted skin temperature, (2) mean rectal temperature, and (3) mean thermal comfort. H0: Thermal sensation is independent of fabric. H5 - H7: There is no significant difference between design for: 0 ° (1) mean weighted skin temperature, (2) mean rectal temperature, and (3) mean thermal comfort. Hg: Thermal sensation is independent of design. Hg; There is no significant interaction between fabric and design. 34 Hypotheses for Research Opjective 2 10’ H11, Ho 0 . Percentage of sweat pp;_absorbed or adsorbed in the test clothing is independent of (l) fabric and (2) design. Hypotheses for Research Objective 3 12 13, H ,Ho . 0 Subjects' anticipated comfort is independent of (l) fabric and (2) design. Hypotheses for Research Objective 4 HM,H15 Subjects' willingness to wear protective clothing is 0 0 independent of (I) fabric and (2) design. Summary Both acute and chronic adverse health effects have been shown to exist in agricultural workers, resulting from exposure to pesticides. Dermal absorption is considered the primary mode of entry into the body. The ineffectiveness of 100% cotton chambray (Orlando et al., 1982) and typical worker clothing ensembles (Davis et al., 1980) has been demonstrated. Thus, the use of protective clothing is con- sidered vital for limiting dermal exposure of agricultural workers. Yet, the clothing which has been designed to provide protection is unacceptable to many of the individuals who have been shown to need it most, including Michigan fruit growers. The present study was undertaken to evaluate the thermal comfort and sensation associated with selected fabrics and designs in an effort to develop a prototype garment that will insure worker safety while maintaining thermal comfort and acceptance levels. The proto- type is being developed using the functional design process, a 35 holistic approach to design that is research based. The findings from this study aided in the formulation of design specifications that have been used for continued development of the prototype design. An ecological framework served as the basis for the thermal-analysis study. CHAPTER II REVIEW OF LITERATURE In order to effectively design and conduct a thermal comfort analysis, to interpret the findings, and to use the results as an aid in designing protective garments, it was necessary to review literature in diverse disciplines. This chapter has therefore been organized into six sections. First, the physics of heat exchange are briefly presented. Second, studies which sought to understand the complex problem of human thermoregulation are reviewed. The findings presented are limited to those that dealt with a heat stress environment. Third, defini- tions of thermal sensation and thermal comfort are given. The rele- vant factors implied in the definitions are discussed. The methods of assessment of thermal comfort and thermal sensation are reviewed in section four. Much of the work cited in the second, third, and fourth sections attempted to study phases of the thermal comfort issue without addressing the influence of clothing on thermal comfort. The subjects were often lightly clothed or nude in these studies. The remaining two sections of this chapter review research which focused on clothing properties as they impinge on thermal comfort. The fifth section examines research dealing with fabric properties, and the final section reviews investigations concerned with the interaction of clothing (either whole garment assemblies or specific design features) with the heat balance of the body. 36 37 Physics of Heat Exchange There are four major avenues of thermal exchange possible between an individual and the environment: conduction, convection, radiation, and evaporation. Conduction Thermal transfer by conduction takes place at the skin surface, when the body is in physical contact with an object which is at a different temperature. Heat will flow to the cooler surface (skin or, for example, clothing) to create equilibrium. Convection Convection is a means of heat transfer which depends on the move- ment of a fluid (air) over a surface which is at a different tempera- ture. Between an individual's body and each layer of clothing, there exists a layer of air. The thickness of each air layer, which is dependent on the fit and drape of the clothing, influences both body heat retention and dissipation. Air is a relatively good insulator, and as such a layer of gtjll air can prevent body heat loss in a cold environment. In a warm environment, however, one would want to maxi- mize air movement in order to transfer excess body heat to the envi- ronment. There are two types of convection, i.e., natural and forced. Natural convection (chimney effect) refers to the movement of warm air after being heated at the skin surface, up along the body toward the head (Hollies & Goldman, 1977). Forced convection implies 38 external influences which contribute to air movement, such as walking, wind, or a fan. Radiation Radiation, the third method of heat transfer, refers to the exchange of electromagnetic energies between facing surfaces that are at different temperatures. Radiant energy exchange is an important consideration in assessing thermal comfort in a hot environment. The absorption and emission of skin and textiles for the low-temperature infrared radiation range is above 0.9 (Fourt & Hollies, 1970). "Thus, for this radiation range, a textile fabric approximates a 'black body' emitting and absorbing energy to the maximum extent" (Fourt & Hollies, 1970, p. 160). The only materials with low emissivity or high reflec- tivity for this radiation range are the metals (Fourt & Hollies, 1970). Consequently, studies have been carried out to investigate the use of low-emission, high-reflection metallic surfaces to minimize radiant heat exchange (Fourt & Hollies, 1970). Such fabrics could be useful in both hot and cold environments. Evaporation Evaporation refers to the process in which a material is con- verted from a liquid to a gaseous state, due to thermal energy (Ruch & Parton, 1965). Evaporative heat loss via the skin can be accomplished in two ways. The first, passive cutaneous diffusion or insensible water loss, occurs by means of diffusion through the skin, and the rate of water loss from this way is small (Ruch & Parton, 1965). The second, regulatory sweating, is of paramount importance for heat 39 dissipation. Without active sweating, the average person loses about 10 kcal - hr'1 - m-2 of body surface, half from his respira- tory tract and half from insensible water loss which occurs at all temperatures and is the only evaporative heat loss below 82.4°F (28°C) (Whitlow, 1971). The quantity of heat loss by evaporation from the skin surface depends on the rate of sweat secretion as well as the capacity of the environment to remove water vapor. The evaporative power of the envi— ronment is a function of: the water vapor pressure gradient from the skin surface to the ambient air, the resistance of clothing to the transfer of water vapor, and the ambient air movement (Winslow & Herrington, 1949). For example, if the air is moist and stagnant, heat loss is limited by the ability of the air to remove moisture from the skin (Ruch & Parton, 1965). When the body secretes more sweat than can be evaporated, there is little advantage for the indi- vidual, since sweat must be evaporated for body heat to be dissipated. Mecheels and Umbach (Hollies & Goldman, 1977) stated that "evapora- tion of one liter of sweat causes a heat loss of about 670 watt-hr" (p. 134). Thermal Response to a Hot Environment The human thermoregulatory system is capable of maintaining a fairly constant deep body temperature under a range of adverse envi- ronmental conditions. A better understanding of the nature of human regulation has been the impetus for numerous investigations. This extensive research has afforded opportunities for the testing of 40 various theories, some of which were conflicting. It is agreed that human temperature regulation is mediated primarily through the activity of the central nervous system. The three essential elements of the system include: the receptors or sensors, which sense the temperature; the integrative structures, which have the ability to compare the sensed temperature to the "normal" temperature and then to activate appropriate responses; and the effectors, which, when activated, would be capable of altering the temperature. The follow- ing section briefly reviews the human thermal response to a hot environment. Receptors The first element of the system, the receptors, is located within the skin. Besides the cutaneous thermoreceptors, the hypothalmus, which is situated at the base of the brain, has been shown to be capable of responding directly to local changes in temperature. It has also been suggested that receptors may exist in other places within the body's core; however, support for this theory is not universal (Ruch & Parton, 1965). The cutaneous thermoreceptors appear to be of two distinct types, cold receptors and warm receptors. Exploration of the skin, conducted in research experiments, has delineated very small areas that respond only to a sensation of cold, and other areas which respond only to warmth. The spaces between seem to be sensitive to neither. About thirteen to fifteen cold spots per square centimeter were found on the forearm, as compared with only one or two warm spots per square centi- meter (Ruch & Parton, 1965). Newburgh (1968) and Ruch and Parton 41 (1965) found that both warm and cold spots show rapid adaptation and are particularly sensitive to rate of change of temperature. This implies that the thermal sensation can differ depending on whether the temperature change is effected gradually or rapidly. Central Nervous System (CNS) Integration Sites The second element of the system, the integrative structures, is capable of processing inputs from the receptors and then designat- ing appropriate responses. The hypothalmus appears to be the major central nervous system integrative site, although the cortex and the spinal cord have subsidiary functions. The major integrative site, the hypothalmus, is a small organ situated at the base of the brain. The hypothalmus appears to have two regions concerned with heat control, each having separate func- tions to some degree. The posterior section is the main center for protection against cold; its activity induces vasoconstriction and shivering, the purpose being to promote and control heat conservation. The anterior portion promotes and controls heat dissipation. This portion of the hypothalmus induces vasodilation and sweating in man and panting in animals. It appears that the centers operate in a manner such that the activity of one inhibits the activity of the other, thereby maintaining a balance. When environmental conditions are such that these mechanisms of control can no longer bring about the necessary adjustments, the situation becomes very serious. Below 80.6°F (27°C), shivering reactions may fail, respiration may be depressed, and cardiac output may become abnormal, presenting a serious 42 threat. Newburgh (1968) gave lO7.6°F (42°C) as the upper limit of temperature for the brain, for survival, although this temperature cannot be tolerated for long periods of time. Effectors The effectors are mechanisms of the body that respond to signals from the central integrative structures, and when activated have the capacity of helping return the system to a balanced state. The effector mechanisms include first of all changes in tissue insulation. If a change in tissue insulation is insufficient to maintain thermal neutrality, other effector mechanisms such as shivering or sweating are necessitated. Metabolism Basal metabolism refers to the "level of metabolic activity displayed by a subject at rest at an air temperature of about 70°F (21.l°C) and at a period long enough after a meal to avoid the specific dynamic action of food“ (Winslow & Herrington, 1949, p. 16). The average value of basal metabolism varies by age, sex, and level of physical fitness. Metabolic rate is equivalent to energy production of the human being. Energy is produced in two forms: mechanical work, which includes the movement of muscles against a weight and constitutes about 10 to 20% of the total energy, and heat energy, which makes up the remaining 80 to 90% of the total (Kuznetz, 1978). A change in activity brings about a corresponding change in metabolic rate, thus influencing the heat energy produced by the body. Table 2 gives 43 an approximate energy cost for various activities. Metabolic rate is also sometimes given in mets. One met equals about 100 watts. Table 2.--Energy costs for various activities. Activity Btu's/Hour Calories/Hour Watts Sleeping 280 70 82 Sitting at lecture 730 183 214 Driving a car in heavy traffic 800 200 234 Slow walking 900 233 264 Washing clothes/ ironing 1000 250 293 Gardening 1380 345 404 Climbing stairs 2860 715 838 Running at a pace of 8 minutes/mile 4000 1000 1172 Swimming the breast stroke at 3 mph 23,100 5775 6768 (From Kuznetz, 1978, p. 50.) Cardiovascular and Peripheral Vascular Control The human body's response to heat stress involves cutaneous vascular dilation. This enlargement of the blood vessels results in an increased blood flow through the skin within a few minutes of sen- sory stimulation. Ordinarily this raises the skin temperature, making it closer to the air temperature, and thus reduces the body's heat gain from the environment. The circulation system plays a critical role in maintaining heat balance in the body in hot environments by 44 being a vehicle for the conductance of heat from the tissues produc- ing it to the skin and the respiratory system for dissipation. Dilation of vascular areas is accomplished by changes in blood pressure, cardiac output, and blood volume.) Upon exposure to a mild heat stress, blood pressure may drop. More intense heat exposure causes the systolic arterial pressure and possibly the diastolic to increase (Newburgh, 1968). Newburgh (1968) found that the volume of circulating blood increased as much as 10% with only "two to four hours of exposure to heat stress severe enough to produce general cutaneous vasodilation, the increase being due largely to increased plasma volume" (p. 207). Exposure to heat stress also results in increases in cardiac output of the order of 1.4 to 1.7 liters per minute, increases which vary little regardless of the resting or exercising state (Newburgh, 1968). Sweat Gland Activity Evaporation is the principal avenue for dissipation of excess body heat. There are two types of sweat glands: the apocrine glands and the eccrine glands. The secretion of sweat may be caused by mus- cular exercise, emotional or mental stress, and thermal stimuli. Sweat, secreted in response to heat stimuli, is produced chiefly by the eccrine glands which are distributed (not uniformly) over the entire skin. The heat-regulatory function of sweating is controlled usually, thought not exclusively, by the hypothalmus. Various researchers have demonstrated this (Newburgh, 1968; Winslow & Herrington, 1949). 45 Yet it has also been shown that the sweat glands are able to respond to excessive local heat stimuli that raise the skin temperature. Sweating is usually not initiated immediately upon exposure to a hot thermal stress. It may take anywhere from five to forty minutes, depending on the heat stimulus, individual differences, whether or not the individuals are heat acclimatized, and the core temperature of the individual at the beginning of the experiment (Newburgh, 1968). For resting man, sweating is, on the average, initiated when skin tempera- ture equals 94.1°F (34.5°C) (Winslow & Herrington, 1949). The rate of sweating increases as the heat stress becomes more severe and as the metabolic rate in work increases. Acclimatization, fatigue, salt intake, and individual variation also affect rate of sweating. Lonngerm Response to Heat Under the broad canopy of physiological adaptation to chronic thermal stress, two terms should be delineated: l. Acclimatization--functiona1 compensation in response to a number of environmental factors in an outdoor environment, over a period of time (several days to weeks). 2. Acclimation--functional compensation in response to a con- trolled laboratory environment, over a period of time (several days to weeks). Acclimation or acclimatization to heat can be characterized by specified and measurable physiological changes as exposure continues. The majority of changes appear within the first four to six days and 46 are complete in ten to fourteen days. The amount of time needed for daily exposure can be quite short--Lind (cited in Folk, 1966) has found that 100 continuous minutes per day was optimal. The changes included increased sweating capacity and blood volume, a fall in the threshold of skin temperature for the onset of sweating, a better distribution of sweat over the skin, increased peripheral conduction, and a drop in rectal temperature and pulse rates (Folinsbee, Wagner, Borgia, Drinkwater, Gliner, & Bedi, 1978; Folk, 1966; Newburgh, 1968; Yousef, Horvath, & Bullard, 1972). Body Temperature The human thermoregulatory system seeks to maintain a fairly constant deep body temperature, approximately 98.6°F (37°C), under a range of environmental conditions. However, skin temperature can vary widely, depending on the site of measurement and environmental conditions. This ability to vary skin temperature is one of the body's mechanisms to insure the maintenance of a constant deep body temperature. Attempts to understand this phenomenon resulted in a theory whereby the body was divided into two concentric shells, each at a uniform temperature. This is where the term core temperature origi- nated (Kuznetz, 1976). With the use of computers and the development of mathematical modeling of the human thermoregulatory system, it is now believed that the human body can be represented as three or more cylinders (head, trunk, and extremities), each divided into two or more concentric layers (Kuznetz, 1976). This supported the observed 47 variability of skin temperature as a function of anatomic site and environmental condition. Summary In order to maintain a constant deep body temperature in a heat- exposure situation, the combined rates of heat gain must be balanced with the rates of heat loss. The human body's response to a warm envi- ronment is illustrated in Figure 7. Environmental heat and/or exercise set in motion a series of responses designed to maintain thermal equilibrium by increasing the body's heat loss to the environment. The anterior portion of the hypothalmus is the heat-dissipation center. It processes inputs from the receptors located in the skin, or it can act as a receptor itself. The hypothalmus designates appropriate responses, including vasodilation, which results in increased blood flow to the skin which ordinarily increases the skin temperature. The body is thought to be composed of three cylinders, each of which contains a series of concentric shells, each exchanging heat with the adjacent shell via conduction. All of the layers exchange heat with the environment by all four routes of heat exchange. The deep body or core temperature can safely vary only within a narrow range about 98.6°F (37°C). Skin temperature varies by both anatomic site and environmental conditions. Sweating is the body's chief means of dissipating excess body heat. The evaporative capacity of the environment (including cloth- ing) impacts on the possible quantity of heat loss by evaporation. HEAT 1) Increased Skin Temperature (— l \ Warm Skin Receptors 48 EXERCISE Increased Deep Body Temperature Increased Central Blood Temperature / Tissue Oxygenation Increased Heat Production Increased l Local Reflex Arc l Local Vasodilation l (Anterior) Sweat Glands / /\ HYPOTHALMUS lllll Sympathetic Nervous System and Endocrine System 1 Reduced Peripheral Resistance Localized Sweating Generalized Sweating General Peripheral Vasodilation l Increased Skin Blood Flow INCREASED HEAT LOSS l Reduced Peripheral Resistance l Increased Skin Blood Flow l Increased Respiration_ Figure 7.--Human thermoregulatory response to a warm environment. (Adapted from Kuznetz, 1976, p. 19.) 49 Thermal Sensation, Thermal Comfort Thermal sensation refers to a conscious experience resulting from exposure to the thermal environment. The ASHRAE Handbook of Fundamentals (1977) specified a neutral thermal sensation as a "sen- sation that is neither slightly warm nor slightly cool" (p. 2). Numerous studies have used rating scales to assess thermal sensation, with a neutral point representing the midpoint of the symmetrical scale. Thermal neutrality, however, is not always synonymous with ther- mal comfort, a distinction which is often not clearly elucidated. Thermal comfortwasdefined by ASHRAE Standard 55-74 (1974) as "that condition of mind which expresses satisfaction with the thermal envi- ronment" (p. 3). Although a neutral thermal sensation would seem to imply optimal thermal comfort, research findings have not always borne this out. McIntyre (1976) cited several studies in which test subjects expressed the most satisfaction with a temperature slightly above or below the neutral midpoint. The natural climatic conditions may impact on subjects' preferred temperature. Subjects in cold climates have indicated a preference for slightly warm temperatures, and the reverse situation has also been documented (McIntyre, 1976). Because of these findings, Rohles, Hayter, and Milliken (1975) suggested assessment of both thermal comfort and thermal sensation when conducting environmental investigations. Thermal Environment There are two other points that should be emphasized regarding the definitions of thermal sensation and thermal comfort given above. 50 First, both definitions refer to the “thermal environment," an encompassing term which includes numerous variables requiring specifi- cation. Much effort in comfort research has been given to both the delineation of pertinent variables and to the combined effects of the specified variables on thermal satisfaction. Fourt and Hollies (1970, p. 9) identified four environmental quantities that should be speci- fied: (a) air temperature or dry-bulb temperature, (b) relative humidity or moisture content of the air, (c) air movement, and (d) mean radiant temperature. These measurements are necessary in order to investigate the heat transfer between the body and the envi- ronment via all four routes of thermal exchange. Fanger (1970) and Hollies and Goldman (1977) suggested the inclu- sion of ambient vapor pressure rather than relative humidity. This is because "water is evaporated across a vapor pressure difference" (Hollies & Goldman, 1977, p. 4). This is an important point because it emphasizes that even if the relative humidity were 100%, one could still evaporate sweat at the skin surface, since the vapor pressure at the skin temperature would be in the neighborhood of 42 mm Hg and the vapor pressure in the air would be considerably less (Hollies & Goldman, 1970). Clothing, as one's nearest constructed environment, affects heat transfer by conduction, convection, radiation, and evaporation. Clearly, properties of clothing which impact on thermal comfort must therefore be identified or controlled (Fourt & Hollies, 1970). The plp_unit, a measure of thermal resistance for a single fabric layer or an assembly of layers, was proposed by Dr. Gagge and his colleagues 51 at the Pierce Foundation over thirty years ago (Hollies & Goldman, 1977). The unit was intended to be readily understood by the nontech- nical audience and was characterized as the intrinsic insulation of the typical business suit of the day, excluding the adhering exterior still-air layer. The method of measuring clo values is given in section four. However, at this point, a limitation of the clo unit should be recog- nized. The clo unit essentially measures the dry heat loss through a material or assembly of materials by convection and radiation. For a resting individual in cold weather this is adequate, but for any other environmental condition in which evaporation of sweat is important, the clo unit alone is not adequate. Therefore, Hollies and Goldman (1977), Fourt and Hollies (1970), and Goldman (n.d.) suggested the inclusion of the permeability index, im, as a means of measuring the resistance of a material to evaporative heat loss. The permeability index was originally proposed by Woodcock (1962). The weight, thickness, and surface area of clothing have also been used to specify clothing (Fourt & Hollies, 1970). Affective Mental Process The second point that should be emphasized regarding the defini- tions of thermal comfort and thermal sensation is that both refer to an affective mental process, i.e., "the conscious experience" and the "condition of mind." Although there are methodological diffi- culties in assessing variables associated with the thermal environ- ment, assessment of a feeling of affective quality is even more difficult. This critical area is addressed in section four. 52 Characteristics of an individual also affect one's response (both psychologically and physiologically) to a thermal environment. Factors such as age, sex, body build, ethnic differences, circadian rhythm, and food intake have all been studied to determine their influence on thermal comfort. Ecosystem Complex Numerous environmental research studies have not or were not able to control the many variables now believed to impact on thermal sen- sation and comfort (Munson, 1980; Rohles, 1967). Recognizing this deficiency, Rohles (1971) used an ecological perspective for organiz- ing and categorizing the variables that he felt required identifica- tion and control, if replicable results were to be achieved. Rohles termed his framework the Ecosystem Complex and depicted it as a three- dimensional solid consisting of three major components, corresponding to the three determinants of an ecosystem, i.e., the individual, the environment, and the interaction between them. Table 3 summarizes the delineation and organization of variables that Rohles felt impacted on thermal sensation and comfort. The physical environment is specified by the physical factors, while the organismic factors identify characteristics of the organism itself which impinge on thermal response to the physical environment. The adaptive factors are those factors which permit the organism to inter- act with the environment in a way that can hinder or facilitate thermal comfort. 53 Table 3.--The ecosystem complex: An organization of variables for the study of thermal comfort, developed by Rohles (1971). Physical Factors Organismic Factors Adaptive Factors Sound *Age Ingesta Light \ *Sex *Clothing Area-volume Body type *Exposure time *Air movement *Psyche Social *Mean radiant temperature Drive Incentive *Water vapor pressure *Physical fitness *Activity level Force fields Circadian rhythm *Temperature *Genetics *Relative humidity *Rohles considered these variables particularly important. Since it is frequently not possible to control all of the vari- ables given in Table 3, Rohles (1978) identified the most critical variables that should be controlled. The physical factors specified are the same variables given by Fourt and Hollies (1970), Fanger (1970), and Hollies and Goldman (1977). Assessment of Thermal Comfort and Thermal Sensation Following a brief historical perspective of thermal-comfort research, methods of assessment are discussed. Historical Development The historical development of human-thermal-comfort research has been achieved through the efforts of researchers from various dis- ciplines, including physiology, psychology, biology, engineering, 54 the health professions, chemistry, and textile science. For the past sixty years, heating and ventilating engineers have been leaders in thermal—comfort research. The major thrust of this research has been directed toward understanding and assessing indoor thermal comfort. The underlying aim of this research effort was to create artificial indoor climates, such that the highest possible percentage of indi- viduals would express satisfaction with the thermal environment (Fanger, 1970). One hundred percent satisfaction was not considered feasible (Fanger, 1970). The classic study of F. C. Houghten and C. P. Yaglou (1923) for the American Society of Heating and Ventilating Engineers (ASHVE) resulted in the development of their "Effective Temperature," an index which combined dry-bulb temperature and humidity into a single temperature scale that described temperature sensation. Yaglou and Miller investigated the notion of effective temperature with indus- trial ventilation problems (1924) and with clothing (1925). During the 19305, physiologists emphasized formulating methods to quantify the energy exchange that takes place during vasodilation, vasoconstriction, shivering, and sweating. Winslow, Herrington, and Gagge (1936) and Hardy and DuBois (cited in Gagge, Gonzales, & Lishi, 1974) carried out studies now considered to be classics. DuBois developed height-weight formulae that could be used to calculate surface area of the human body (given in Newburgh, 1968). These formulae remain important today in order to quantify thermal transfer by all four methods. 55 During the 19405, the orientation of much of the thermal-comfort research shifted toward a determination of the human tolerance limits for adverse thermal environments. The level of performance that sub- jects were capable of achieving under thermal stress conditions was also emphasized. Eichna, Ashe, Bean, and Shelley (1945) provided a summary of studies conducted (both chamber and field studies) to investigate thermal response to heat-stress environments. Eichna et al. (1945) carried out an experiment to determine the environmen- tal limits at which disability begins under conditions of heat stress. World War II also served as an impetus for this research effort. The limitations of human performance of the military in both hot and cold environments was clearly demonstrated during the war (Gagge et al., 1974). Increased attention was accordingly paid to designing arctic and tropical protective military clothing, which would facili- tate improved human performance under environmental stress conditions. The interest of the military in thermal-comfort research has continued to the present time. The comfort research during the 19505 continued to emphasize determination of tolerance and performance levels under severe thermal- stress conditions. However, the focus was directed toward developing standards for tolerable working conditions, primarily in mines and factories (Gagge et al., 1974). Belding and Hatch (1956) investi- gated the thermal comfort of steel workers, and Wyndham (1962) studied the thermal comfort of miners in the hot South African gold mines. The past twenty years have witnessed the continued dual effort by scientists specializing in thermal comfort for military applications, 56 and scientists emphasizing thermal comfort for indoor conditions, most notably the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). Assessment Technigues Thermal comfort and sensation have traditionally been determined via an objective or a subjective approach or a combination of both. Rohles (1974) suggested that in order to study feelings about comfort or sensation, it was important to distinguish between the affective mental process and the "underlying physiological process that it parallels" (p. 98). Rohles referred to subjective approaches as methods of impression, and objective techniques as methods of expre — sion. Methods of impression. The objective of methods of impression is to obtain a subjective account of the test subjects' feelings about the thermal environment under investigation. This has been accomp- lished in three ways: (1) determination of preferred temperature, (2) use of various rating scales in environmental chambers, and (3) use of the same scales in field studies. The environmentally controlled chamber studies offer the researcher the advantage of being capable of monitoring and controlling many of the variables given in Table 3. Yet, as Bronfenbrenner (1979) succinctly pointed out, “the laboratory does have its special vulnerabilities, particu- larly when results are taken as applicable to everyday life” (p. 118). Goldman (n.d.) suggested that field evaluations ”should never be car— ried out until the 'homework' in the laboratory has been completed 57 and then only as a validation of the laboratory findings under field conditions" (p. 17). The method of direct determination, pioneered by Fanger in the 19705, produced more consistent results than either chamber or field tests. This method allowed a subject to find his/her preferred tem- perature by requesting changes in the chamber temperature until he/she was satisfied. This experimental procedure, which used only one test subject at a time, was very expensive and time consuming. Fanger has found that age, sex, previous thermal experience, and time of day did not affect his results (McIntyre, 1976). The most commonly used technique for assessing thermal feelings involved the use of rating scales, one of the earliest being a five- point scale developed by Yaglou (1927). Although various investi— gators have used scales which ranged from three points to twenty-five, seven remains the most frequently used (McIntyre, 1976). The Bedford and ASHRAE scales, shown in Table 4, are two commonly used seven- point scales. Examination of the scales shows that the ASHRAE scale refers only to thermal sensation, whereas the Bedford scale combined sensation and comfort. The choice of seven is supported by research evidence, which suggests that the number of separate estimates that a person can unambiguously assign to a one-dimensional stimulus is rather small (McIntyre, 1976). On this basis, many researchers have concluded that subjects will be unable to distinguish more than seven levels of thermal sensation (McIntyre, 1976). 58 Table 4.--The Bedford and ASHRAE thermal comfort rating scales. Bedford Scale ASHRAE Scale Much too warm Hot Too warm Warm Comfortably warm Slightly warm Comfortable Neutral Comfortably cool Slightly cool Too cool Cool Much too cool Cold Recently, Winakor (1978) has been experimenting with a ninety- nine-point semantic-differential-type instrument which would assess both thermal comfort and thermal sensation. Pairs of words describ- ing characteristics of the clothing worn and removed are also included in this instrument. At this time, it has not been administered to a sufficient number of subjects in different settings to establish its reliability. Rohles (1974) has recommended the use of a nine-point scale to measure thermal sensation. The scale is identical to the ASHRAE scale except that the categories very hot and very cold have been added to the extremes of the ASHRAE scale. McIntyre (1976) cautioned that it should not be assumed that the ratings on the seven- and the nine-point scales will correspond; rather, this should be evaluated when sufficient comparative data are gathered. Rohles' (1978) rationale for extending the seven-point scale was to spread the variability of the overall distribution of responses. Rohles had found that there -‘ 59 was a tendency for subjects not to use the end points, thus reducing a seven-point scale to effectively five. McIntyre (1976) investigated the behavior of the Bedford and ASHRAE seven-point scales in detail, for both field studies and chamber experiments. Methods of gxpression. Methods of expression are objective measures of physiological bodily changes. Depending on the given environmental conditions under study and the objectives of the researcher, various physiological criterion measures have been used, the most widely used being mean skin temperature, rectal temperature, metabolism, the rate of regulatory sweat secretion on the skin sur- face, and mechanical efficiency for doing external work (Gagge et al., 1974). Eichna et a1. (1945) varied the temperature/relative humidity conditions to identify the upper limits of heat-stress environments that men could tolerate and perform effectively in. The thirteen young male subjects were first trained to march with ease and then acclimated to simulated dry and humid heat. The men were required to march, carrying a twenty-pound pack a specified length of time under various heat-stress conditions (ranged between 90.7°-97.2° E.T. The "old“ Effective Temperature, ET, was an arbitrary index combining temperature, humidity, air movement, and thermal sensation; Rohles et al., 1979). Neither clothing nor food and drink intake was con- trolled. Heart rate, rectal temperature, and respiratory rates were measured at hourly intervals. Skin temperatures for six body locations were determined with a radiometer at the end of the test. Three 60 environmental zones were identified as (1) relatively easy, (2) unde- .ss.iirable, and (3) impossible. For the relatively easy zone, average ‘i I’lternal temperatures remained under lOl°F (38.3°C), between 101°F and 102°F (38.9°C) for the undesirable zone, and over 102°F for the “i mpossible zone. Skin temperature for the individual varied little t>gyr anatomic site for all environmental conditions investigated. Skin ‘t: that an evaluation and a comparison of the relative thermal com- 17(3‘lt‘t afforded by protective garments versus commonly worn clothing (:(3 LJld be achieved. The second objective was a serious concern since (1E3'1:a reported in the literature on which areas of the body receive beEsticide deposition during actual field spray operations were g l 78 limited and fragmentary. Although the present overall project included a "deposition study," this component was planned for the summer following the thermal analysis. It was therefore important to anticipate what the pattern of deposition of pesticide spray during application might be. It seemed reasonable to consider that pesti- cide deposition might be primarily localized on the upper portion of the body, thus suggesting the necessity of a partial protective body covering. Both of the objectives were met in the two-piece design shown irn Figure 11. The design consisted of ggpim_jeans and a long-sleeved ‘tncaditional-styled shirt, constructed in each of the test fabrics. ‘Tlius, only the shirt fabric was varied, and the fabric for the jeans VVEiS held constant. The second and third levels of the independent variable cieesign were two variations of a one-piece coverall. Henry's study (‘1 980) indicated that growers were divided in their preference for C>r1e- or two-piece work clothing designs; thus it was considered impor- 1teant to include one-piece variations. As indicated in Figure 10, the movement analysis and the 1triermal comfort literature provided inputs into the development of the prototype designs. The thermal comfort literature suggested that loose, flowing designs with wide openings at the neck, wrist, and lower leg would maximize internal air flow throughout the garment and 1"351(2‘i1itate the exchange of internal air with outside air. However, these general principles were in contradiction for the need to main- tain closed openings to minimize dermal pesticide exposure. Also, iIIIIIIIl--.___ 79 Legend: A. Shirt--fabric varied to include all three test fabrics B. Jeans-—denim fabric held constant Figure ll.--Two—piece design, Design 1. T c><35e-fitting clothing posed a serious hazard to the grower. Based C>r1 data obtained from surveys in the states of Ohio, Michigan, New 'Y<)r~k, Wisconsin, Louisiana, Nebraska, Minnesota, Indiana, Illinois, Olceegon, West Virginia, Alabama, California, Missouri, and Maryland, 0\Iezr 200,000 injuries occur annually to farm residents, their help, arni visitors (Pfister, 1976). Farm machinery was involved in 22% of these injuries, and almost one-third of the tractor injuries resulted TFCJHI the victim being caught in or between the tractor and another ObCIEBCt (Pfister, 1976). Clothing that is loose or clothing with k 80 something hanging from it can be and has been a contributing factor to injuries resulting from these accidents. Figure 12 illustrates design 2, a one-piece coverall design that was developed to cover the body in areas that were anticipated to be areas of pesticide deposition under actual use conditions. The loack torso and shoulder area were kept free of seams, and the armscye sseamline was lowered, since the upper back and shoulder area were (:onsidered likely high-deposition areas. Seam leakage remains a prob- 'lenithat has not been fully solved for protective clothing now avail- able. DESIGN FEATURES A. Highsecuredcollar B. Dropped armscye C. Velcro half—belt adjustment D. Concealed zipper E. Shoulder seam removed, back cut in one with front yoke F. Velcro-tabbed wrist adjustment G. Half-belt, secured at center back H. Action pleat Figure 12.--One-piece coverall design, Design 2. 81 Additional design features of note included the concealed zipper extending to the collar and adjustable wrist and neck openings. The lower edge of the sleeve included a velcro tab that can be left completely open for maximal outside air exchange when the grower is not spraying or can be readily closed with a gloved hand during resump- tion of spraying. The narrow stand-up band collar fits the neck closely for dermal protection, but the zipper can be easily lowered to improve comfort when the grower has stopped applying pesticide. The back action pleat was designed to help facilitate movement and to add looseness to the back torso area for improved thermal comfort. "The half-belt, which was secured at the center back, can be adjusted riot only to improve fit but also to promote thermal comfort when 1Fully extended. This position could give a loose fit through the vvaist, increasing the possibility of internal air flow. The second coverall variation, design 3, was very similar to ciesign 2; however, it featured raglan sleeves rather than the dropped airmscye and the back-front-yoke construction of design 2 (see Figure 1 3). This variation also included a ventilating panel on the ipgigg ()f'the garment as illustrated in Figure 14. The purpose of the panel vvas to facilitate wicking of perspiration away from the body to the ()LJter fabric layer to promote thermal comfort. The ventilating panel ccansisted of two trapezoidal-sahped pieces of outer fabric positioned uricier the back raglan seamlines, sewn to a center 100% cotton mesh piiriel. The reasoning that prompted the use of the outer fabric was CCDricern for seam leakage in the back torso area. 1" 82 pmwFQ compo< xuwa Lopcmu pm umgsomm .p—mnlew: chma an? -pMFPpcw> Lowgmch pcmspmsnuw pmwez umnnmu-ogu_w> Lwaqwu chMmucou ucprmzwcm ppmnim—m; oeu_w> m>wm~m :mmem LmFFou umesuwm 5mm: mmmzhou womwaimco--.m_ ogzmwd .: .w .m .m .o .u .m .< 83 INSIDE BACK DESIGN FEATURES A. Outer fabric-- A designed to cover raglan seamline B B. 100% cotton mesh, used for ventilating panel Figure l4.--Inside ventilating panel for Design 3. Other design possibilities for improving the convective and Gaiuaporative capacity of the garment were considered and finally t~eajected. Design features such as air vents, zippered air vents, taeellows, and the use of multiple outer fabrics (for example, a less {Drcotective but more comfortable fabric used in combination with a 'FEIbric offering superior resistance to pesticides) were not included ‘irl designs 2 and 3 for several reasons. First, the deposition study had not been completed before the thermal-analysis study. Thus, it was not known if and where it would be safe to locate air vents or Tess protective fabrics. It was felt that following the deposition Study, such features could readily be added if the deposition findings SuDported their inclusion. Second, bellows were rejected because of Concern for pesticide deposition and the subsequent problem of pesti- CT de removal. 84 Fabric. The underlying rationale for the specification of the test fabrics was to permit a comparison between a commonly worn fabric and fabrics with demonstrated improved resistance to pesti- cide spray penetration. If a fabric could be shown to offer greater dermal protection and a level of thermal comfort similar to what is now worn, then the feasibility of meeting the ultimate objective of the overall project would be enhanced. Three levels of fabric were specified to include two fabrics that offered superior resistance to pesticide penetration and ppg 'fabric that was commonly selected by the grower for its comfort. The 1 iterature on occupational exposure to pesticides and information ()btained from extension agents were used to specify chambray as the ssliirt fabric considered representative of what was commonly worn by ngowers. The effectiveness of chambray] andfiveother fabrics as t>aarriers to penetration of pesticide spray had been evaluated in a $51:udy conducted before the thermal—analysis study. The results of 1:?iis study (Orlando et al., 1981) are given in Table 7. Examination of Table 7 clearly shows that four fabrics ()fifered significantly better resistance to pesticide penetration than Clianmray]. Two of the superior fabrics, fabrics 1 and 2, as well as (itlaxnbray1, were selected for further examination in the thermal- analysis study. Fabric 1 was a disposable polyethylene-coated 100% spun- b<>ruded olefin fabric. The fabric consisted of very fine polyethylene 1:lbers interconnected in a network structure that was self-bonded under heat and pressure. The physical properties of fabric 1 are 85 mostly unaffected by organic and inorganic chemicals, including acids, bases, and salts. This fabric has been and is now being used for chemical-protective clothing. Table 7.--Summary of results of Guthion Penetration Study, conducted by Orlando, Branson, Ayers, and Leavitt (1981). Guthion® 1.19/sz Fabric Inner Gauze Layers Outer Fapric Totals 3:???n;: 149/ cm ug/cm Rangga 1 .014 3.30 3.31 A 2 .018 3.35 3.37 A 3 .018 3.35 3.37 A 4 .023 3.16 3.18 A 5 .460 2.95 3.41 B Chambray] .564 2.83 3.39 C aValues followed by unlike letters are different at .01 level. Fabric 2 was a thin microporous polymeric film of polytetra- fluoroethylene (PTFE). The combination of pore size and pore volume [Droduced about nine billion pores per square inch (Tanner, 1977). "The large number of pores and the thinness of the film facilitate the ciiffusion of perspiration in the vapor phase through the fabric. Yet, 'tlie small pore size and the hydrophobic nature of the film retard the Penetration of liquids. The fabric 2 film has been bonded to a variety of fabrics in e‘i'ther a two- or a three—layer construction, thus resulting in a fximily of laminates. The fabric tested for the penetration and 86 subsequently for the thermal analysis was a three-layer structure consisting of an outer layer of rip-stop nylon and an inner layer of 1.3 oz/yd2 nylon knit laminated to the film. This fabric has been developed for application in the area of camping and backpacking and has not been used for pesticide protective gear. Chambray, a 100% cotton woven shirting fabric, was considered representative of what is now often worn by the grower. Table 7 pro- vided data indicating that this fabric was ppp_as effective as fabrics l and 2 in preventing pesticide penetration. The description of the 'three levels of both independent variables is summarized in Table 8. Fabrics l, 2, and chambray1 were procured as yard goods. [Designs 2 and 3 (both coverall designs) were constructed in these 'tflnree fabrics. Design 1 (the two-piece design) test garments were (Statained by purchasing four pairs of prewashed denim jeans (size EBES x 32) and two 100% cotton chambrayz shirts (size 15%). Shirts vveere also constructed in fabrics l and 2 to resemble the purchased ssfiirts. Thus, two chambray variations were used. Data for both (:riambray fabrics have been combined and are referred to as fabric 3 ‘tfiroughout the remainder of this work. Table 9 summarizes the physical characteristics of the test fabrics. The physical characteristics of both chambray fabrics were Very similar. Unfortunately, due to limitations of the laboratory, itlf’ormation on moisture regain was not obtained for the test fabrics. ‘V1!“ permeability was determined at a pressure of 0.5 inches of water vwith a Gurley Tester. The considerable difference in the rate of afir~ flow through the various fabrics should be noted. This test 87 Table 8.--Summary of the independent variables, fabric and design. Independent Variable LEVEI Description Fabric Fabric 1 Disposable polyethylene-coated 100% spun-bonded olefin fabric; shown to offer excellent resistance to pesti- cide spray Fabric 2 Three-layer laminate structure con- sisting of an outer rip-stop nylon layer, a thin microporous polymeric film of polytetrafluoroethylene, and an inner layer of nylon tricot; shown to offer excellent resistance to pes- ticide spray Fabric 3 100% cotton woven chambray shirting fabric; representative of commonly worn work shirt fabric; shown to be less effective as a barrier to pes- ticide spray than fabrics l and 2 [)esign Design 1 Two-piece design, consisting of denim jeans and a traditional-style shirt; only the shirt fabric was varied in the test fabrics to provide comfort data on a partial protective covering Design 2 Coverall with dropped armscye, front yoke cut-in-one with back torso, high collar, back action pleat, and adjustable velcro closures at the waist and lower arms Design 3 Coverall with raglan sleeve, venti- lating 100% cotton mesh panel on back inside torso, high collar, back action pleat, and adjustable velcro closures at the waist and lower arms 88 method is suggested as an indicator of the “breathability” of a fab— ric. Thickness was determined with a Custom Scientific Instrument with pressure equal to 8.654 g/cm2 for denim and 4.385 g/cm2 for the remaining fabrics. Table 9.--Physical characteristics of test fabrics. Test Fabric Fabric Thread Counta Air Fabrics Weighta Thickness (Warp, PermeabilityC (oz/yd2) (Inches) F1111ng) ft3 /min/ft ) Fabric 1 2.52 .011 NA \Fpppic 2 2.96 .015 136,114d 0.0 Fabric 3 ‘77 Cham] 4.95 .017 74,54 173.83 Chamz 3.65 .019 70,47 213.33 Denim 14.76 .044 65,47 4.33 aTesting done according to the ASTM 01910—64 method. bTesting done according to the ASTM 01777—64 method. cTesting done according to the ASTM 0737-75 method. dSurface fabric only. Because the outer garment was an independent variable in the Sizudy, itwas important to insure that all subjects wore identical uricjergarments. Therefore, fifteen sets of white 70/30 cotton/ P<>1.yester blend undershirts (size medium) and briefs (size 36) were PlJr‘chased for the study. White cotton crewsocks, available through tile: Institute for Environmental Research, were also provided for each test subject. 89 All test garments were pre-washed and hung to dry before con- ducting the study. This was done since washing softens fabric 2 and therefore might influence the thermal comfort perceived by the sub- jects who would wear this fabric. Order in which garments were to be tested was by random selection. Dependent Measures The dependent variables which were measured included subjects' rectal temperature, weighted mean skin temperature, percent of sweat that evaporated, and the affective measures of thermal sensation and thermal comfort. Weighted mean skin temperature was measured with skin ther- mistors located as shown in Figure 15, and computed using formula (1), as given in Rohles, Milliken and Krstic (1979, p. 12): where: Twmsk = weighted mean skin temperature tskc = skin temperature measured at the chest tskl = skin temperature measured at the lower leg tska — skin temperature measured at the lower arm The thermal sensation response was assessed by the 9—point thermal sensation scale (see Figure 16) developed by Rohles et a1. (1979). The thermal comfort rating was the summed value of ratings that subjects assigned to each of six pairs of polar adjectives on 90 the thermal comfort ballot illustrated in Figure 17. This comfort ballot was developed by Rohles et a1. (1979). Location 1. Right pectoral region of the chest 5’ 2. Radial surface of left arm (or right arm if subject was left-handed) 3. Fibular surface of the left eg Figure 15.--Location of three skin temperature thermistors. It was hypothesized that the fabric and/or design which facilitated evaporation of sweat would improve the subjects' per- ceived thermal comfort and the accompanying physiological responses. The assessment of sweat production and evaporation in previous studies has been determined by weight change (Fourt & Hollies, 1970). To estimate total sweat production, ordinarily the weight of the subject 91 Name Test No. comfortable bad temperature pleasant good ventilation unacceptable uncomfortable temperature satisfied Vote No. uncomfortable good temperature unpleasant poor ventilation acceptable uncomfortable temperature dissatisfied Figure l6.--Therma1 comfort ballot. Vote No. ______ Name & No. Test No. Circle the number beside the adjective that describes how you feel. i—JNOO-hU‘IOWNmKO Very hot Hot Warm Slightly warm Neutral Slightly cool Cool Cold Very cold Figure 17.--Therma1 sensation ballot. 92 without clothing is taken before and after the test. If no water has been consumed, then the difference in weights gives the total sweat secretion. If the subjects were allowed to drink, then the quantity would need to be added to the original pre-test weight. However, while total sweat can be measured by weight change, the researcher was primarily interested in the percentage sweat evaporated. In order to investigate this issue, three sets of pre- and post-test weights were taken. The dressed subjects were weighed immediately before and after the two-hour chamber test. Therefore, post-test subject weight change reflected a change in the subject's body weight as well as a change in the weight of the clothing. This departure from the usual procedure was considered acceptable because actual body weight was not the variable of interest. Concern was focused instead on weight change, and this could be obtained. The second set of pre- and post-test weights was taken of the test clothing in sealed plastic bags. Again, the emphasis was placed on the weight difference. Therefore, the additional weight of the bag (same coded bag was used for before and after weights) was not seen as objectionable. Thermos jugs of ice water constituted the third set of weights obtained. No attempt was made to account for sweat run-off that occurred during the test or during the undressing process. While sweat run—off was a very minor problem during the test, the severity of it during the undressing process is unknown. Second, sweat that adhered to the body after the test clothing was removed was not accounted for. Third, sweat picked up by the subject's towel during the experiment was not 93 determined. These limitations contributed to measurement error for this variable. In order to compute total sweat secretion, all three sets of weights were used in the following manner. Taking the difference in weight of the thermos yielded how much water was consumed and therefore the weight gain of the subject had no evaporation occurred. Consider the following hypothetical situation. Assume an individual is within a sealed micro-environment and that the person drank two pounds of water. This two pounds of water should therefore be contained within the person, his clothing, or the sealed environment. If the clothed person gained one pound, then the other pound must be in the environ- ment (sweat evaporated). Determining the change in clothing weight, for example 1/3 lb, yields the amount in the clothing (sweat adsorbed and/or absorbed in the clothing). Thus, a total of 1-1/3 lbs of sweat has been produced, 1 lb of which evaporated. This example illustrates the manner in which the three sets of weights were used to estimate percentage evaporated sweat. This quantity included respiratory evaporation and insensible evaporation. These could have been esti— mated from the literature and subtracted. However, the amount would have been constant for all subjects and therefore would not have altered the results relative to fabric/design comparisons. With measurement error already a problem with these data, it was considered appropriate to refrain from using approximations from the literature. The findings instead could be examined relative to the levels of inde- pendent variables. 94 The amount of evaporated sweat was calculated by the follow- ing equation: se = (w] - W2) - (s2 - s1) (2) where: W1 = pre-test thermos weight W = post-test thermos weight S1 = pre-test clothed subject weight S = post-test clothed subject weight = total sweat evaporated The amount of sweat not evaporated could be determined by the change in weight of the test clothing, as shown in equation (3). 5a = 02 — c1 (3) where: C1 = pre-test clothing weight C2 = post—test clothing weight S6 = sweat absorbed or adsorbed by the clothing The total amount of sweat secreted was computed as given in equation (4). 5S = 56 + se (4) Percentage sweat evaporated was then calculated. Experimental Design A 3 x 3 complete factorial experimental design with six replications was used. The research design for this study is illustrated in Figure 18, where F = fabric, 0 = design, and C = controlled climatological conditions. 95 C F1 51 . . . . S6 DI F2 S7 . . . . 512 F3 513 . . . . 518 F1 519 . . . . 324 D2 F2 525 . . . . S30 F3 S31 . . . . 536 F1 S37 . . . . S42 D3 F2 S43 . . . . S48 F3 S49 . . . . $54 Figure 18.——Research design of thermal—analysis study. Twelve test sessions of two hour duration were held in a six- day period in the spring of 1980. The number of test subjects in the test sessions varied from two to six subjects, as shown in Table 10. The variability was due to either an insufficient number of subjects that had successfully passed the physical examination or to failure of test subjects to report for their assigned test session. To alleviate the second problem, one alternate test subject was sched- uled for sessions nine through twelve. Sample Fifty-four male students, between the ages of 18 and 25, attending Kansas State University, served as test subjects. The students were recruited through newspaper advertisements and were 96 Table 10.--Number of test subjects per test session. Session Number of Subjects 1 3 2 3 3 5 4 2 5 6 6 6 7 4 8 2 9 6 10 6 ll 6 12 5 required to pass a physical examination before being accepted as a test subject. Each qualified test subject was expected to complete pee testing session and was paid $20 for his participation. Test subjects were randomly assigned to wear one test garment for the entire test session. Facilities and Equipment The study was conducted in a Sherer Environmental chamber located in the Institute for Environmental Research at Kansas State University. The chamber was a 12 ft x 24 ft (2.5 m x 7.3 m) room with an 8 ft (2.4 m) ceiling. The floor was carpeted, the walls were painted white, and white acoustical tiles covered the ceiling. The 97 room was furnished with six vinyl—cushioned straight-backed chairs and six sets of two nine-inch wooden steps that were positioned next to the chairs (see Figure 19). The test subjects used these chairs and steps in the experiment. In the center of the room, a rectangular table held the junction boxes to which the skin thermistors and the probes were connected. The dry-bulb temperature and the relative humidity within the chamber were maintained at 85i2°F and 60% relative humidity throughout each testing session. One small table, which was used to hold necessary supplies including magazines, newspapers, metro- nome, clock radio, ballots, pencils, paper, extra surgical tape, and the test protocol, was positioned against one wall. One straight- backed chair, for the researcher, was placed next to the table, facing the test subjects. Fluorescent lighting was held constant throughout the experiment. The pre-conditioning room was located outside but immediately adjacent to the environmental chamber. This area was carpeted, the walls were panelled, and six wooden tablet—arm chairs were arranged in a semi-circular fashion along three walls. The tablet-arm chairs held each subject's equipment for the test, including three Yellow Spring Instrument Company thermistors for measuring skin temperature, one Yellow Spring Instrument Probe 701 for measuring rectal tempera- ture, a canvas harness and a digital heart—rate device for monitoring heart rate, and a clipboard containing data—acquisition forms. A large desk and chair, for the researcher, were placed on the fourth wall. A Digital Automatic Temperature Acquisition System was used 98 .LmnEmzu prcoECOLw>cm Loewsm esp cw newEszcm wee muuwnnzm pmmeii.mfi weaned 99 for measuring and recording every five minutes skin and rectal temperatures of the test subjects as well as the air temperature of the test chamber. The system was housed in a control room outside the chamber. A Holmes clinical balance scale was housed in a room adjacent to the pre-conditioning room. Procedure for Obtaining Subjects Two weeks prior to the scheduled testing, announcements recruiting male volunteers for the study were made in the Kansas State University school newspaper. Those interested in participating were directed to the Institute for Environmental Research to register for the study. At registration, volunteers were asked to read an orientation statement describing the general purpose and protocol of the study, risks that might be incurred, and the subjects' obliga- tions, rights, and remuneration. (See Appendix A1.) Having read this statement, if they were still interested in participating, they were asked to complete a Medical History Questionnaire (see Appendix A2) and to schedule their physical examination. The physical examination (see Appendix A2, p. 6), which was conducted by a registered nurse, was patterned after the class 11 Flight Physical Examination as specified in the Army Regulation AR40-501C29, dated January 29, 1974. Additional measures included: electrocardiogram, exercise habits,and cardiovascular fitness as estimated by the Astrand Method using a Schwinn Bicycle Ergometer. Their responses to the Medical History Questionnaire and the results of the physical examination were reviewed by a physician. Those 100 judged to be physically qualified were subsequently scheduled for the experiment. They were given instructions not to take drugs, medica- tion, or alcohol twelve hours before the test and not to eat or drink anything except water after 11 p.m. the evening before their scheduled test. (See Appendix A3.) The instructions also included information on clothing to be worn, the standard breakfast provided, and a reminder of the importance of reporting for the scheduled test. A specific breakfast instruction sheet (see Appendix A4) was also given to each test subject at this time. Test Protocol Pilot Study A pilot study, consisting of one complete test session, was conducted to determine and correct any problems in the planned test— ing procedure. The environmental chamber was maintained at 73°:2°F and 50% relative humidity. Six male subjects participated in the pilot study. No major changes were made as a result of the pilot study. However, potential problems such as walking up and down stairs with the rectal probe and skin thermistors were recognized. Precau- tionary actions were decided upon to minimize these problems. Pre-test Protocol Test subjects were called the evening before their scheduled test to encourage adherence to the instructions and to serve as a reminder of the scheduled test date. On the morning of the scheduled test, subjects reported to the Kansas State University Student Union building at their assigned time (either 7:00 a.m. or 9:30 a.m.). A 101 male research assistant (Kansas State graduate student) met each group of subjects at the Union. This procedure assured that subjects received and ate the high—protein 600—calorie breakfast as directed. The standard breakfast consisted of: 120 m1 (4 oz ) of orange juice, 120 ml (4 oz ) of skim milk, scrambled eggs, a 50 g broiled lean beef patty,andone slice of dry toast. Students were instructed to eat all of this, plus all of the water they desired. No substi- tutions were permitted. During this time, the researcher and an assistant (Kansas State undergraduate student) were completing final preparations at the Institute for Environmental Research. The test garment, one pair ofSOCkS,and one set of underwear which had been placed in coded plastic bags, weighed,and the data recorded by the researcher earlier that morning, were placed on the rung beneath each tablet—arm chair in the pre-conditioning room. Coded water jugs, which had been filled with ice water, weighed,and the data recorded, were positioned next to each chair. (See Appendix B1 for the data sheet used to record these weights.) The rectal probe, three skin thermistors, and the harness for the heart-monitoring device were hung on the back of each chair. A pencil and the data-acquisition forms (Appendices B1, B2, B3, B4, B5), which were secured to a clipboard, were placed on the surface of the tablet—arm chair. Examination of the environmental chamber was also performed to ensure that all chairs and steps were correctly positioned, that necessary supplies were available, and that the cords required for measuring skin and rectal temperature were properly fastened and that coding was legible. 102 Orientation Following breakfast, the test subjects and the male research assistant reported to the pre-conditioning room for the orientation. Test subjects were assigned a tablet-arm chair, which contained all of the supplies previously prepared by the researcher. At this time the researcher introduced herself and explained that she was conducting a study to determine how man responds to his thermal envi- ronment. The importance of following the directions they would be given wasstressed, and appreciation for their participation was expressed. Their attention was then directed to the clipboard with materials placed before them on their chairs. They were asked to read and if still willing to participate, sign an Agreement of Release Form (see Appendix B2). Other materials that identified the test subject, their rectal and skin thermistors numbers (see Appendix B3), and a short health questionnaire (see Appendix B4) were subsequently read and completed by the subjects, as directed by the researcher. Each set of forms, upon completion, was picked up by the investigator and reviewed. The researcher read the following orientation statement to the subjects concerning the test in which they were to participate. Throughout the reading of the statement, the investigator paused at appropriate places to hold up equipment to familiarize the subjects with the various monitoring devices. The purpose of the study in which you are participating is to determine how man, wearing a specific clothing ensemble, responds to his thermal environment. You will be wearing three skin temperature thermistors to measure your skin temperature. Your rectal temperature, which will be monitored throughout the study, will not only provide valuable data for the research project but will also allow 103 us to monitor your body's core temperature to ensure your safety. You will monitor your heart beat periodically throughout the test. The test will proceed in the following manner: in about five minutes you will be given a coded plastic bag containing an outer garment, socks and underwear. You will take your plastic bag, the rectal probe and the heart monitoring harness with you to the men's room. There, you will change your clothing, insert the rectal probe about 6 inches and put on the harness in this manner (demonstra- tion stressing the need for the harness to fit snugly). Once you have completed dressing, you will return to the pre-test room, so that the investigator or the assist- ants can put on the skin thermistors. After you have been weighed, you will be ready to begin the test. The test will be a two-hour test. While you are there, you will be asked to walk up and down the steps provided to a specified cadence. Although this activity may seem contrived, it is essential that each of you walk as directed to ensure that you are all doing an equal amount of work. You will also have time to sit and rest. You may feel free to read or talk if you desire. However, you may ppt_discuss the experiment, the garment you will be given or any other aspect of the test while you are dressing, during the test itself nor for two weeks after the test. While you will be seated, you will be asked to complete two ballots. You have examples of these ballots on your clipboard. [Directions for completing the ballots were given. In order to assure that the subjects understood the directives, the test subjects were asked to immediately complete two examples. The investigator picked up the ballots (Figures 16 and 17) and reviewed them to minimize problems of misunderstanding of the scales.] You will be asked to respond to one of these ballots immediately after entering the test chamber. I shall collect this ballot, then you will respond to the second ballot which will be collected immediately. This pattern of rest and ballot completion, followed by walking will be continued throughout the two hour test. Ice water has been provided for you. You may drink as much as you choose, but you must exercise care not to spill any. You may leave the experiment at any time. Any change that suggests danger to your physical well—being will cause you to be removed from the test. A registered nurse will monitor your vital signs. 104 At the end of two hours, you will leave the test chamber, your weight will be taken, and monitoring devices W111 be removed. You will then return to the men's room, change your clothing, carefully putting all of the test cloth1ng 1nto the coded plastic bag that it originally came in, and return to this room. At that time, you will be asked to complete several summary questions. You will then be paid twenty dollars for your participation. Are there any questions? Dressinggof Test Subjects Upon completion of the orientation, the test subjects with their equipment and clothing, and the male graduate student proceeded to the men's room where the subjects changed their clothing. The presence of the male graduate student minimized potential problems associated with insertion of the rectal probe, handling the coded plastic bags, coded clothing,and the harnesses for the heart- monitoring devices. Skin Temperature Thermistors Having completed the dressing process, the test subjects returned to the pre-conditioning room, where the investigator and her two assistants taped skin thermistors to the subjects' skin. The thermistors were attached with micropore surgical tape to the right pectoral region of the chest (see Figure 20), the radial surface of the left arm (or the radial surface of the right arm if the subject was left-handedL,and to the fibular surface of the left leg. The heart-monitoring device was secured to the harness. Care was taken that each person was dressed uniformly with sleeves, collars, closures, Velcro tabs,and shirts all positioned and secured similarly. The dressed subjects were weighed,and the weight was entered on the data sheet. (See Appendix Bl.) 105 Figure 20.--P1acement of skin thermistor on the right pectoral region of the chest. 106 Test Chamber The subjects, carrying their clipboards and ice water, entered the test chamber, seated themselves on an assigned chair,and waited to have their coded chest, arm,1eg, and rectal sensors plugged into the appropriately coded extension cords and numbered positions in the junction box. The table in the center of the room held all of the junction boxes. As soon as all of the subjects' sensors were attached to the junction boxes, the test began. In order to simulate the amount of work performed in applying pesticides by the air-blast spray method, an activity pattern was established such that the metabolic cost of the activity was about three mets. This moderate level of activity corresponded to the estimated metabolic cost of driving a tractor. A pattern consisting of a nine-minute rest period followed by six minutes of walking up and down the steps to a specified cadence (maintained with a metronome) was established. During the first eight rest periods, the subjects recorded their heart rate (as indicated on their digital heart-rate device) on their thermal sensation ballot (Figure 21) which was then completed and collected by the investigator. Immediately thereafter, they recorded their thermal comfort responses, which were collected. During the first rest period after ballots were collected, the investigator demonstrated the manner in which the subjects were to walk up and down the steps to the cadence of the metronome. This was done to ensure uniformity among the subjects and also to demon- strate how to hold the numerous lengthy cords while walking. Having 341111.111.‘ .1 1. i 107 .poFFmo covpmmcmm .ill 11.4111... . 111.11%. J. ; . FmEmep one no mum; pemm: mcmueoomg pawns: WII _N messed 108 done this, the investigator seated herself in the chair facing the subjects for the duration of the test. She requested the subjects' thermal sensation and thermal comfort responses again every 15 minutes for a total of eight times. Skin and rectal temperature readouts and chamber temperature were being taken automatically every five minutes and checked by the technician. If any thermistor was malfunctioning the technician informed the researcher, and the deficiency (such as a loose connection or an improperly inserted rectal probe) was corrected. The rectal temperature readings were also carefully monitored to ensure the safety of the test subjects. An individual whose rectal temperature increased 2°F was removed from the test. In such instances where the data indicated the possibility that a subject might have to be removed, the registered nurse remained in the test chamber as a precaution. Typically,however, one of the two regis- tered nurses in attendance would periodically check on the subjects, rather than stay throughout the test. Procedure Following the Chamber Test At the end of the two-hour exposure, the subjects' sensors were disconnected, their post—test weight was taken by the investi- gator on the Holmes clinical scale in an adjacent room, and recorded on the appropriate data sheet. (See Appendix B1.) Skin- temperature thermistors and the heart-monitoring devices were removed by the investigator and her assistants. The male assistant took the subjects to the men's room, where they changed their 109 clothing, depositing all of the test clothing in their original coded bag and the rectal probe in a container provided. During this time, the investigator weighed the subjects' coded water jugs and entered the post-weight on the appropriate data sheet. (See Appendix B1.) When the subjects returned to the pre-conditioning room, they were asked to answer the two summary questions below. They were instructed to choose only one answer. (See Appendix B5 for the summary data sheet.) I found the clothing that I wore for the study to be . . . cooler warmer about the same . as I expected. The test you have just completed was conducted to measure thermal comfort of protective garments at 85°F. Knowing that this clothing would provide protection against harmful chemicals in your work, indicate your willingness to wear this garment: I would be willing to wear it under these temperature conditions. I would wear it if the temperature was less than 85°F. 1 would wear it only if required to do so. I would not wear it. After completing the summary questions, the subjects were paid $20.00 for their participation and were asked to sign a receipt form (see Appendix B7) acknowledging that they had been paid. The subjects were given a post-test information sheet (see Appendix B6) which outlined possible symptoms of heat stress, and they were dismissed. The coded plastic bags,each containing all of the clothing worn by a subject for the test, were then weighed and the post-weight was recorded on the appropriate data sheet. (See Appendix B1.) The soiled clothing was stored until laundered later 110 the same afternoon. The entire test procedure was repeated with two tests being completed per day. Laundry Procedures A Kansas State University undergraduate student in the Department of Textiles and Clothing was hired to assist in the daily laundering of the test clothing. The laundry was done using the Textile and Clothing Department's research laboratory located in Justin Hall. The laundry was transported in large plastic bags from the Institute for Environmental Research to Justin Hall by the researcher and her assistant at the end of each test day. Because the fabrics varied greatly relative to fiber content, fabric struct- ure, color,and recommended laundering procedures, it was not possible to follow the same procedure for ell of the clothing. Instead, the clothing was separated into three groups with a uniform procedure established for each group. The equipment used to conduct the laundering included a Kenmore heavy-duty washing machine and electric dryer, both model 600. A United Systems Corporation (CTID 312422) digital Thermocouple Thermometer was used to measure the temperature of the wash and rinse water for each washing procedure. Ivory Snow was used as the detergent since it was recommended by the manufacturer of one test fabric in order to maintain the fabric's breathability. Table 11 lists the specification of the laundry variables for each of the clothing groups. After the cleaning procedures were completed, all of the laundry was folded and transported back to the Institute. The garments in groups two and three werehung, and those in group 111 one were placed as folded in a closet provided. Socks were commer- cially laundered. Table ll.--Specification of laundry variables for three clothing groups. \ Clothing Groups Laundry Variables Group 1: Group 2: Group 3: Undergarments Fabrics 1 & 2 Fabric 3 & Jeans Wash water : temperature 160.2°F 150.4°F 150.4°F 1 Rinse water , temperature 150.4°F 83.4°F 83.4°F ' Wash cycle setting Normal Knit, Normal Delicate Length of time of wash cycle 10 min 6 min 10 min Amount of detergent 250 ml 250 ml 250 m1 Dryer temperature setting High Low Almost High Length of time of drying cycle 50 min 20 min 50 min Dryer cycle setting Normal Delicate Normal Data Treatment The statistical treatment of the data was accomplished in two integral phases. The first phase focused on a graphical repre- sentation of each of the dependent measures over time by fabric and design. The second phase was concerned with statistical—significance testing of the various hypotheses (cited in Chapter I), which were developed to meet the objectives of the study. 112 Phase 1 In order to graph mean rectal temperature; weighted mean skin temperature; mean skin temperature for the leg, arm, and chest; mean thermal comfort responses and mean thermal snesation responses by fabric and design over time, a number of preliminary steps were required. First, the data had to be examined for a common truncation 29103: In the event that a subject had to be removed before the test was completed, an incomplete data set would result for that subject. It was decided to graph the dependent measures by fabric and design to the last time period for which complete data were available on all subjects. , Second, all temperature data for each subject were examined for deviations from an expected temperature range. It was anticipated that skin temperature would vary between 90°F and 98°F and that rectal temperature would be between 97°F and 101°F. This preliminary scrutiny of the temperature data was essential to distinguish out-of—expected- range data points due to data-recording irregularities from those due to individual differences of subjects. Initially, the computer soft- ware package Mini-Tab was used to plot each set of temperature data over time for each level of fabric and design. (See Appendix C1.) Because the researcher desired greater precision in examining theSe data, a computer listing of all temperature data per subject was examined. (See Appendix C2.) In this way, any suspected deviation could be evaluated relative to the rest of a subject's temperature data. 113 Out-of—range data points determined to be caused by recording irregularities comprised about 1% of approximately 5,400 temperature data points. Missing data were therefore not a serious problem in this study. Such data resulted ordinarily from a skin thermistor becoming detached from the surface of the skin due to perspiration. There were also two instances in which rectal probes gave out-of- range values due to improper insertion. Once a bad value had been determined, cell means were calculated from the remaining clean values and substituted for the appropriate bad values. Following the determination of the common truncation point and the examination of the temperature data to ensure clean data, the computer software system, Statistical Plotting On-Line Command System (SPOCS), was used to graphically display the data over time. This system, which was designed for the Control Data Corporation (CDC) 6500 mainframe at Michigan State University, was available through the Department of Entomology. The truncation point determined for the temperature data was used also for graphing the thermal comfort and thermal sensation responses by fabric and design over time. There were no missing data for these two perceptual measures to the truncation point. However, the following preliminary steps were necessary for the thermal comfort measure before graphing could be initiated: first, coding the data and second, computing the thermal comfort response from the semantic differential scale. The thermal comfort ballot, shown in Figure 16, was coded by assigning a scale of one to nine for each of the available spaces 114 from right to left on the ballot. Thus, a value between one and nine would constitute a subject's response to ppe_pair of polar adjectives. The responses for each of the seven pairs were coded as indicated above and summed for a total thermal comfort vote of between 7 and 63. Lower scores indicated feelings of comfort and satisfaction with the thermal environment. Thermal comfort and thermal sensation responses were subse- quently graphed by fabric and design over time. Phase 2 The second phase of the data analyses focused primarily on the statistical-significance testing of the hypotheses cited in Chapter I. The present study was planned to examine the effects of two independent variables, fabric and design, each with three levels, on five major dependent variables. Data on two physiological measures, weighted mean skin temperature and rectal temperature, and two percep- tual measures, thermal comfort and thermal sensation, were gathered over time. The fifth major dependent variable, percentage of sweat production that evaporated, was obtained as a single response to the environmental conditions. Recognizing that the assessment of man's thermal response should include both physiological and perceptual measures as related aspects of a single response, multivariate statistical analysis was used to analyze the dependent measures as a whole. The advantage of multivariate models was that with conceptually related measures that are intercorrelated and have different variances, the statistical 115 analysis was not invalidated. Rectal temperature, weighted mean skin temperature, and the perception of thermal comfort were used as the set of dependent measures. All of the analyses were executed using the MULTIVARIANCE computer program developed by Finn (1974). Since the three dependent variables were measured over time, it was necessary to specify a distinct point in time for which the data would be analyzed. The truncation point for the temperature data, which had been set at time equal to 90 minutes for Phase 1 of the analyses, was chosen as the appropriate point in time. The responses to the ejypp_thermal comfort ballot (Figure 17) were chosen for analyses with the temperature responses since the sixth ballot was administered approximately at time equal to 90 minutes. The remaining two major dependent measures, percentage of evaporated sweat and thermal sensation, were each analyzed separately. Volume of total sweat produced by subjects for fabric and design was computed from pre- and post-test weights of subjects and the quantity of water that they consumed. The change in weight (pre- and post-test) of all of the subjects' clothing was calculated to give an indication of the volume of sweat adsorbed or absorbed by the test clothing. The volume of sweat evaporated was taken as the difference between the volume produced and the volume absorbed or adsorbed. Percentage of evaporated sweat was computed so that a comparison and analyses could be completed by fabric and design. The presence of measurement error was a concern for this dependent measure. Thus, it was not included in the multivariate analysis. Because thermal sensation votes were clustered at the upper end of the scale, this variable was not 116 included in the set of dependent measures. Instead, thermal sensation responses were analyzed by chi-square analysis for design and fabric. In addition, information on two other minor variables of interest was sought. The investigator recognized that the test sub- jects for this study were college students, not growers. It was anticipated that the physiological responses and, to a lesser degree, the perceptual responses of the student test subjects would be some- what invariant if the experiment were repeated with growers, while maintaining the same environmental conditions. However, student responses to the two summary variables, anticipated comfort and will— ingness to wear protective clothing, could well differ from responses that growers would give. This was considered particularly so for willingness to wear protective clothing. Response to this variable would likely be influenced by one's perception of the potential danger, working familiarity with chemicals, past physical effects of handling chemicals, and feelings, attitudes, and practices of family members regarding chemicals. Recognizing the lack of generalizability of these data to other populations, this information was sought antici— pating comparison of these data with data from a user-satisfaction study planned for the future. Chi—square analyses were used to analyze these two measures by fabric and design. Summary The study was designed to evaluate the thermal response of male college students in a hot environment while wearing selected designs and fabrics with known chemical protective characteristics. 117 Approval was obtained from Michigan State University and Kansas State University Committees on Research Involving Human Subjects to conduct this study. The experimental design of the study, a 3 x 3 complete fac- torial, permitted the main effects and the interactions of the inde- pendent variables to be investigated. The laboratory study was conducted in an environmental-controlled chamber, located in the Insti- tute for Environmental Research at Kansas State University. All of the environmental variables relative to the human environed unit, the human- constructed environmentz, and the human-behavioral environment were maintained as specified. The determination of controlled HCEZ vari- ables was made in order to simulate typical Michigan summer climatologi- cal conditions and to facilitate future research plans. Five dependent measures were investigated: weighted skin temperature, rectal temperature, sweat production and evaporation, thermal comfort, and thermal sensation response. Anticipated com— fort and willingness to wear protective clothing were also explored. Subjects were tested in a two-hour test session in groups of two to six during the spring of 1980. Subjects were recruited through newspaper advertisements and required to pass a physical examination prior to being accepted as a test subject. Healthysubjects wore one test garment for one test session and were paid $20 for their participation. The analysis of the data involved first a graphical presen- tation of the dependent measures by fabric and design over time. The 118 second component of the analyses was concerned with hypotheses test- ing. Univariate, analysis of variance, chi-square analyses, and multivariate statistical techniques were used to test the hypotheses of interest. CHAPTER IV FINDINGS AND DISCUSSION This study investigated the influence of selected protective garment designs and fabrics on subjects' conscious feelings of thermal comfort and sensation and their accompanying physiological responses in a hot environment. The controlled environmental conditions of 85° 1 2°F, 60% relative humidity were specified to simulate typical summer weather conditions in the fruit-growing sector of southwestern Michigan. The investigation involved testing the thermal response of 54 male subjects who each wore one test garment for one two-hour test session. The findings from the testing of these subjects are reported in this chapter. Thermal response was evaluated in terms of: thermal comfort ratings, thermal sensation ratings, weighted mean skin temperature (and skin temperatures at the arm, leg, and chest, which were used to compute mean skin temperature), and rectal temperature. In addi— tion, the total volume of sweat secreted by the subjects during the test, the volume of sweatcontainedin the test clothing, and the volume of evaporated sweat were estimated from pre- and post-test weights. Two summary questions administered to the subjects imme- diately after their test provided retrospective data on the subjects' anticipated comfort when they were first given the clothing and 119 120 their willingness to wear the garment after learning of its protec- tive qualities. The analyses of the data consisted of two integral components. The thrust of the first phase was directed toward a graphical repre- sentation of each of the dependent measures over time by fabric and design. This phase was particularly useful to the investigator from a design perspective. The second phase of the analyses focused on statistical-significance testing of the various hypotheses of inter- est. Univariate analysis of variance, chi-square analyses, and multi- variate statistical techniques were used. This chapter has been organized into two major sections. The summary plots of the dependent measures are presented in the first section, Phase 1. Results of the inferential statistics are given in the second section, Phase 2. Phase 1 The graphical representation of the dependent temperature measures by fabric and design have been plotted for the first 90 minutes of the experiment. This truncation point was specified since two subjects had to be removed from the experiment prior to the com- pletion of the test because their rectal temperatures increased 2°F. The presentation of the findings from Phase 1 has been par- titioned into, first, summary plots of the temperature data for jeppie_followed by a display of the thermal comfort response. Second, the same dependent measures are presented for geeigp, Last, the major insights gained through examination of the summary graphs are discussed. 121 5811112 In a heat stress environment, as the human body attempts to maintain a fairly constant deep body temperature, certain physio- logical responses are activated within a short period of time follow- ing sensory stimulation. The test subjects in this experiment were also asked to sustain a moderate level of physical activity corres- ponding to a metabolic rate of approximately three mets. Figure 7 (shown in Chapter II, p. 48) shows the dual effect of heat and exer- cise on the human thermoregulatory system. One of the initial physiological responses is that of vascular dilation. This enlargement of the blood vessels permits an increased blood flow through the skin and ordinarily elevates the skin tempera- ture. Thus, the circulation system plays a critical role in maintain- ing the body's heat balance during exercise in a hot environment by being a vehicle for conducting heat produced in the tissues to the skin and the respiratory system for dissipation. The ability of the body to tolerate a wide skin temperature range is evidenced in the following graphs. Thermal comfort has been frequently associated with a mean skin temperature of 91°F to 93°F without sweating. Fanger (1970), however, found that this was true only for sedentary individuals. For higher activities, Fanger's results suggest that comfort is achieved with lower skin tempera- tures and moderate sweating. Weighted mean skin temperature. Weighted mean skin tempera- ture was computed as given in equation (1), Chapter III. All of the 122 following skin temperature graphs show a similar alternating pattern over time. This reflects the activity pattern developed for the experiment, which included a nine-minute rest period followed by a six—minute period of walking up and down the steps provided. Figure 22 presents the mean weighted skin temperature of subjects wearing fabric 3, chambray. Chambray fabric was chosen for investigation because it is frequently chosen by the agricul- tural worker for its social acceptability, durability, and comfort. Notice that a clear over-all slight downward trend from an initial mean skin temperature of less than 94°F is apparent. This indi— cates that evaporative and/or convective cooling was taking place during the 90 minutes of exposure to the test conditions. Close examination of Figure 22 indicates a slight pattern regarding design emerging. The ventsuit design seems to be fairly consistently reporting the highest temperatures, with jeans (two- piece design) mostly indicating the lowest temperatures. However, the pattern is not clearcut, particularly from time equal to 40 minutes on. Figure 23 presents very similar data for fabric 2, although the initial temperatures are slightly higher than temperatures of subjects wearing fabric 3. Both fabrics indicate low temperatures approximating 92°F. Design for fabric 2 is not showing a clear pattern, although the coverall seems to be frequently reporting the lowest temperatures. 123 The two-piece design of jeans and shirt of fabric 2 is above the coverall for most of the temperature readings. The data given in Figure 24 for fabric 1 are quite different from the temperature data for fabrics 2 and 3. Notice that the temperature of the subjects wearing farbic 1 is initially greater than the initial temperatures reported for subjects wearing the other two test fabrics. The over-all trend is also clearly upward, and this appears true for all three designs. The subjects wearing the ventsuit design seem consistently to have the highest mean skin tem- peratures, and those wearing the coverall usually have the lowest temperatures. Comparison of the three graphs (Figures 22, 23, and 24) clearly indicates that subjects wearing fabric 1, regardless of the design variation, experienced higher mean weighted skin temperatures than the rest of the test subjects, up to a 3°F difference. Weighted mean skin temperature, being a weighted computed value, can mask indi- vidual body site temperature data. Therefore, summary plots of skin temperature for the emm, leg, and epeep_are presented to explore further differences in skin temperature as a function of fabric. Lower arm mean skin temperature. Figures 25, 26, and 27 present the mean skin temperatures at the lower arm for the three test fabrics. The initial arm skin temperatures of all of the sub— jects were between 94°F and 95°F, regardless of fabric or design. The pattern of alternation which characterized the graphs of weighted mean skin temperature is similarly present here. 124 31 El Ventsuit 0_ X Coverall o t 2—piece 51 Q- “lo K :Ju F . cr" , I ‘ . uJ‘3 , 1. . ,4, x . " / \ ' I \ \ :0- 4.» ‘2’/’”\\ ,4 ,. m \ / \\ I, \\ 4‘, I / ‘ \x / \\ II. \ I \\ Fm. ( \1 / \, ,l , p/ / ‘x \ u. ’ V 3/ a... o 3.1 8 *1 1 ‘1 71’ *1 1 1 1 1 0 10 20 fl ‘0 50 50 10 30 90 111115 (MINUTES) Figure 22.--Weighted mean skin temperature for fabric 3. 125 :1 E] Ventsuit 01- X Coverall a 3 2-piece b-l o 0-1 “’0 O! :)m p. n (to I; /A\ O! 4\ / \ E‘\‘ 7' l~ \. ‘ ’ \\ .. " ; o *. ' ~ I ‘ .X Z \ / s \ \ . / e r ‘ I d I \ e I \\ \ m \\ I x I \\ I \ / I'- ! \\*’ \r I \ 4’ \ h, :4 I.\\"/ ‘\\ {I \ /, \ 'i a- o 3.1 3 1* 1 *1 1 1 1 1 1 1 ll Ill 20 3O 40 80 50 lll 80 91 llflE lHlNUlESl Figure 23.-—Weighted mean skin temperature for fabric 2. 126 3 1 m Ventsuit X Coverall 94 #J w—i \ TEMPERRTURE 1 1 1 10 20 30 4O 50 60 10 80 90 llliE lHINUIES) (:90 ‘ Figure 24.--Weighted mean skin temperature for fabric 1. TEMPERRTURE 127 m Ventsuit A Coverall 0 2-piece =90 1 1 1 1 1 10 20 30 40 50 60 10 80 90 TIHE MINUTES) — .— .- Figure 25.-—Lower arm mean skin temperature for fabric 3. 128 m Ventsuit 01 * Coverall ‘ 2-piece TEMPERRTURE 94 a- O a... C a 1 1 l 1 l 1 1 T 1 ll 10 20 11 40 511 60 70 00 so llllE MINUTES) Figure 26.--Lower arm mean skin temperature for fabric 2. TEMPERRTURE 129 [I] Ventsuit X Coverall 0 2-piece =9 0 111 211 30 411 511 611 10 30 90 llHE lHINUlESl Figure 27.-—Lower arm mean skin temperature for fabric 1. 130 Examination of Figures 25 and 26 shows a similar over-all slight downward trend over time. Note that there are differences, however, regarding the influence of design. Subjects wearing the fabric 3 ventsuit tend to experience the lowest arm skin tempera- ture, whereas those subjects wearing the same design in fabric 2 show higher temperatures, particularly after 20 minutes. At the end of the test there was about a 1°F difference between subjects wearing fabric 2 and those wearing the fabric 3 ventsuit. The coverall and the two-piece jeans assembly are indicating the lowest arm temperatures for fabric 2, yet the coverall appears to be showing the highest temperatures for fabric 3. Figure 27 reiterates the over—all upward trend depicted for weighted mean skin temperature for fabric 1. The influence of design is more clear—cut, however. Subjects wearing fabric 1 in the vent— suit design experienced higher temperatures than those wearing the other designs, with those in the coverall indicating lowest tempera- tures. Notice that the influence of design is more pronounced for fabric 1. Lower leg mean skin temperature. The graphs for leg tem- perature (Figures 28, 29, and 30) are distinguished from the previous plots for several reasons. First, the initial temperatures, although not uniform across fabric or design, are lower than those reported previously. Second, the over-all pattern for all three fabrics is a slight increasing trend over time. And third, the pattern of alter- nation is amplified particularly for fabric 1, shown in Figure 30. 131 2 1 E] Ventsuit 04 A Coverall t 2-piece BS 1 TEMPERRTURE 94 93 1 1 l I 1 10 20 I] 40 50 60 ll) 80 ”NE (HINUTESI =90 83.. Figure 28.--Lower leg mean skin temperature for fabric 3. 132 a 01 m Ventsuit * Coverall 0 2-piece 95 96 l l TEMPERRTURE 94 Q90 _1 IIHE lHINUTESl Figure 29.--Lower leg mean skin temperature for fabric 2. 1 I 1 1 1 1 10 20 30 40 50 60 10 80 so 96 1 95 _1 94 4 TEMPERRTURE T 133 E] Ventsuit X Coverall 3 2—piece I " " \ I, \ ’7 \ A ' ‘\ l‘ \m ' ‘7 i ’ \ \ " \ 1 1‘ I: \l I ‘ 'l‘ 1‘ 1 \\ g I \ u I / ‘\ '/ \ I l \‘x . /’ \‘l C. \\ '/ \ 1 7 \ ‘ ' \ \\ j \ \< ’I k \\I’/ \\ ‘1 /' 8 A U 7/ / \X\ / ( \fil ‘ _‘ \,WII \\l\ / I \ I " fl \ / 'V x/I \¥/ 3 ‘ I I; ‘ I l r ‘8 X ‘1 l =9 0 1 1 1 1 10 20 11 40 50 60 10 80 91 IIHE (MINUTES) Figure 30.--Lower leg mean skin temperature for fabric 1. 134 Persons wearing fabric 3, regardless of design, showed a consistent tight mean leg skin temperature, suggesting that design had little influence on leg temperature. This was true even though subjects wearing the design 1 variation had bottom weight denim jeans on. Figure 29 for fabric 2 showed a similar pattern, although it was not as tight. There seemed to be a trend for those wearing the ventsuit to have the highest temperatures and those in the cover- all the lowest. The arm temperature data alluded to a similar notion. The marked amplitude of the graphs in Figure 30 is character- 'istic primarily of the coverall and ventsuit designs. Also, this [battern appears more obvious as the exposure time increases. These tnwo designs are also indicating the highest skin temperatures, not ()nly for fabric 1 but for all of the test fabrics. The data suggest ‘tfliat the heat energy produced in walking is not being dissipated well ‘fkar those subjects in fabric 1, designs 2 and 3. Mean chest skin temperature. Chest temperature factors l'ieeavily in the formula that is used to compute weighted mean skin ‘t:eamperature. Thus, the data displayed in Figures 31, 32, and 33 are <:>'f° significant import to the determination of this dependent measure. 4‘3\ rapid appraisal of these three figures reveals dramatic differences. The data for subjects wearing fabric 3, exhibited in Figure 31, ‘i ‘1 lustrate an over-all downward theme over time. The impact of design 1i =31 more visible for this fabric than in previous plots. The ventsuit design showed higher temperatures initially. However, the coverall deSign after 75 minutes showed equally high temperatures. Subjects TEMPERATURE 135 E] Ventsuit * Coverall 3 2-piece 1 T 1 1 1 1 211 30 40 50 611 ll) 80 90 1111f MINUTES] Figure 31.--Mean chest skin temperature for fabric 3. l O? 08 1511351411115 136 E] Ventsuit ¥ Coverall # 2—piece 1 m 40 1 1 m ll] 20 30 50 ill lll ill 90 TIHE MINUTES) Figure 32.--Mean chest skin temperature for fabric 2. TEMPERATURE 137 m Ventsuit ’ X Coverall 9 2-piece 39 O 1 *1 1 ill 20 11 40 ill 60 10 11 ”NE lfllNUlESl 8‘ Figure 33.--Mean chest skin temperature for fabric 1. 138 wearing the two-piece design experienced the lowest skin tempera- tures after the first 20 minutes. A similar downward pattern is evident in the data given in Figure 32 for fabric 2. However, the impact of design, if any, cannot be discerned. Those in the coverall design show the lowest chest temperatures. The influence of design is readily observable in the dra- 1natic graph for fabric 1 (Figure 33). Two designs, the ventsuit and the coverall, show a distinct upward trend with the ventsuit design «exhibiting the highest chest temperatures. Yet, design 1, the two- 13iece design, surprisingly has shown a downward trend. Thus, the [aresence of jeans on the lower portion of the body appears to have lielped these subjects achieve a reduced chest skin temperature. This (downward trend is in clear contrast to all of the preceding skin 'tenmerature plots for fabric 1. Rectal temperature. While skin temperature can safely vary ‘vvithin a wide range, rectal temperature cannot do so. A subject whose rectal temperature increased 2°F above his/her temperature taken at the beginning of the experiment was removed from the test. 4¢\. registered nurse who was in attendance at the Institute routinely <::l1ecked on the subjects throughout the experiment. There were two 153.14bjects whose increased rectal temperature necessitated their removal ‘1F’Ioom the experiment prior to its completion. In these two instances, ‘12:?1e nurse remained in the test chamber to ensure the health and S afety of the subjects. 139 In general, Figures 34, 35, and 36 show an increasing trend over time. The rate of increase for fabric 3, as seen in Figure 34, is less than the other two fabrics. Also, this graph indicated that design 1, the two-piece jeans variation, after 20 minutes exhibited the highest rectal temperature, with no distinction between designs 2 and 3. Figure 35 does not suggest any distinct pattern other than its over-all increasing trend. The data displayed in Figure 36, however, clearly indicate a higher rectal temperature for design 3, 'the ventsuit. Both subjects who were removed from the test were vvearing fabric 1; one wore the ventsuit and the other wore design 2, 'the coverall. Mean thermal comfort votes. The perceptual measure of 'thermal comfort was assessed by a semantic differential scale. The t>allot was administered eight times at 15-minute intervals during the two-hour experiment. However, complete data were not available for the seventh and eighth votes due to the removal of two subjects. ‘T1ne method of determination of the total thermal comfort vote from ‘t:l1e semantic differential scale denoted that higher thermal comfort ‘urcates represented greater perceived discomfort with the thermal ‘ B TEMPERATURE 94 \ / / / \ / n... X Fabric 1 0 3 Fabric 3 «.4 E] Fabric 2 a 8 1 1 1 1 1 1 1 1 1 0 10 20 II 40 50 50 10 80 90 ”NE MINUTES) Figure 41.--Mean arm skin temperature for design 1, the two—piece jeans assembly. 149 o 01 0d 0 [‘d a O ’*--*\ 1 -1 ’ \*- 111'3 L X a”, \ m ” ‘§-\r,“\\ *I’ ‘\ I’ \ 3 ’ Hg AK}; Y E I ' ‘0—.._\ .' , m‘k 5 1‘“. V )\ \ mini ' ' as \~ ~e/ \‘ m u ’- U m- o 01- X Fabric 1 a 3 Fabric 3 *1 1]] Fabric 2 8 1* 1 1 1 1 1 1 1 0 ll] 20 30 40 50 50 10 El) lIflE lHINUTES) Figure 42.--Mean arm skin temperature for design 2, the coverall. 150 a o- a x _* I F-i X\ I-"* ’l- \\ I, ’l\ [I \‘\ [I \\ I, \‘/ 1’ ‘f ‘ ’ Y 111- J‘ ’I Y ui° I" I I! DID ago [I we 53° [LI 1- in 0 «~ X Fabric 1 O 3 Fabric 3 «3 [3] Fabric 2 o 8 1 1 1 7‘1 1 1 1 I l 0 10 20 30 40 50 50 10 00 9) TIME lHINUTESl Figure 43.--Mean arm skin temperature for design 3, the ventsuit. 151 over time is apparent for all three designs in fabric 1. This trend is contrary to that shown by fabrics 2 and 3 for all three designs. The downward trend suggests that evaporative and/or convec- tive cooling was taking place over time with these fabrics. Figure 43 is particularly noteworthy for three reasons. First, the mean temperature of subjects wearing fabric 1was clearly higher in the ventsuit relative to the two other designs. Also, the temperature difference between the test fabrics indicated greater disparity than the other designs. And third, the temperature data for those wearing fabric 2 are above the data for those in fabric 3. Figures 41 and 42 indicated very similar temperature data for fabrics 2 and 3. Mean leg skin temperature. As expected, the data presented in Figure 44 are very similar. Recall that all of the subjects assigned design 1 wore denim jeans, only the shirt fabric was varied. Therefore, the leg temperature data in Figure 44 are for subjects all wearing denim jeans. Data for subjects wearing design 2, the coverall, are given in Figure 45. Data for those wearing design 3, the ventsuit, are illustrated in Figure 46. Note that Figures 45 and 46 display simi- lar results. The strong influence of fabric 1 is again apparent but ‘in a different way. Subjects wearing fabric 1 again exhibited the iiighest leg skin temperature readings, particularly in design 3, the ‘\'entsuit. However, the clear upward trends demonstrated in Figures 38, 39, 40, 41, 42, and 43 are not found in these data. Rather, an '1 rfitial increase followed by an alternating pattern of notable TEMPERQTURE 94 92 152 ‘1 ,0—4 / ~e/ * Fabric 1 0 Fabric 3 E] Fabric 2 cyan 8.. 10 20 I1 411 511 50 10 00 11n£ lfllNUlES) F‘igure 44.--Mean leg skin temperature for design 1, the two—piece jeans assembly. 153 O 01 0" 0 9-1 0 o. u1° I M ; ” ‘\ F“ \ D I \ , \! " 1 E- :1 I, \ I \ , ‘ \ m ‘\ I ! I, ‘ I ‘\ E] I \ I \\ ' 5 1f ‘ 1 \ a. ‘fi "\ K I ‘\ ’ ’I‘ ‘ \ f” ‘ \ A “ 22¢» , \ ,, t\ (I 1 \\ \gfi ‘\ ‘ I \ l ' /i l: 1 u- * Fabric 1 5 ° 3 Fabric 3 .._ E] Fabric 2 0) £3 1 1 1 71 1 1 1 1 0 10 20 30 40 50 60 10 00 llflE lHlNUlESl F=igure 45.--Mean leg skin temperature for design 2, the coverall. 154 o- o o 01 (s. a 1‘1 5 ’1! g. I 1 l’ \‘ / ‘ LIJ 1’ \\ ,1 I’ \ I; " F m I! \ I’ \ / '\ I 1 I, DID-1 /‘ I \\ I, \\ /. y, A I PC I \\ I 1 I \ I ' I g f \ 1 1 I \Y/ " I I ‘ ' i ’ I In. , 2.0 “’ / / \ ,/¢’ / 0” A «117% * Fabric 1 o 3 Fabric 3 «a E] Fabric 2 a 8 1 1 *1 1 1 1 1 1 1 ll 10 20 I) 40 50 60 10 80 9) IIHE (HINUIESl F=igure 46.--Mean leg skin temperature for design 3, the ventsuit. 155 amplitude can be seen in Figures 45 and 46. Also, the data clearly demonstrated that no downward trend was taking place for any of the test fabrics. Further examination of Figures 45 and 46 points out another distinction. For the coverall design, fabric 2 was consistently showing the lowest temperatures, whereas with the ventsuit, fabric 2 was indicating higher temperatures than fabric 3. Mean chest skin temperature. The dominant theme that subjects wearing fabric 1 regardless of the design variation experienced higher skin temperature readings, so pronounced for weighted mean skin tem— perature and mean arm skin temperature, was again reiterated with the mean chest skin temperature data. Figure 47 shows a clear downward temperature trend for subjects wearing either fabric 2 or fabric 3. Although lower temperatures char— acterized fabric 3 during the beginning of the test, temperatures for fabrics 2 and 3 are very similar after the first 45 minutes. Data displayed in Figures 48 and 49 are very similar. How— ever, note that in design 3, the ventsuit, subjects wearing fabric 1 experienced particularly elevated skin temperature readings, almost to 99°F. That represented approximately a 5.5°F difference between subjects wearing fabric 1 versus fabric 2 after a 90—minute exposure ‘to the environmental conditions. This temperature differential for <1e5ign 3 was greater than with either design 1 or 2. Rectal temperature. The distinctive pattern that most of 1:he skin temperature data have demonstrated was not as clearly 156 81 Out a l 5" *\ "‘ //‘\ I’ \\ I a I’\\ ‘, v-4! 1-4: \!,er 7“!” I \ ’ I fi’ 0 an ’ u1°1 ’ 5 (I 2)» 5° . 1r -' " / m A\\//\ / \ (L‘ \ g \ , :0 \ / \ ‘/ , f / \ . I E \ z. \ '. /\ \ ’ o 5«/ \' / \. \/~ 9 / x F b - * ‘ «1 a r1c l o I t Fabric 3 w E] Fabric 2 o 8 1 1 1 1 1 1 1 1 1 ll 10 20 El) 40 50 fill 111 00 91 IIHE lHlNUTESl Figure 47.--Mean chest skin temperature for design 1, the two-piece jeans assembly. 157 x——X m- [U (I m' D ID E:: a: 11] fi m - Z 0 l1] '— m- (I «- X Fabric 1 O a Fabric 3 “_ fl Fabric 2 (I 8 1 1 1 1 1 1 1 1 1 0 10 20 30 40 50 60 70 80 SI] TIHE [MINUTES] Figure 48.--Mean chest skin temperature for design 2, the coverai]. 158 a F I Q‘ 1—-§- o ,’ 1{ / Ax /}\ ,}\~{ 3‘ I, ‘}-X \‘\ I, )\ ,1 ‘11-" ,’ ‘1’ 0-1 l.—{ u1° ,’ m: , a 3 ) r-g ‘w/ \ ,, \ m I b' / \ )\ g‘fl \\\J/ \ / \ a '- \ / z. t\ . \r a O . , :13 J \J \ / /1‘ / (”-1 ' \l / / “d x Fabric '| " V o I 3 Fabric 3 fl [3 Fabric 2 a 8 1 1 1 1 1 1 1 I l 0 10 20 30 40 50 60 10 80 90 ”NE MINUTES] Figure 49.--Mean chest skin temperature for design 3, the ventsuit. 159 elucidated by the mean rectal temperature data. Figures 50, 51, and 52 document an increasing temperature trend over time. Surprisingly, fabric 1 for the two—piece jeans ensemble seems to be indicating lower mean rectal temperatures than the other two test fabrics (see Figure 50). As the time in the chamber continued, the temperature data for the three fabrics merged to a similar level. No clear pattern was discerned from scrutinizing Figure 51. However, the data acquired for design 3, the ventsuit (shown in Figure 52% werein accord with the skin temperature data previously presented. Those wearing fabric l experience higher rectal tempera- j tures than those wearing fabric 2 or those assigned to fabric 3. A 1 l°F difference is apparent for fabric 3 and fabric l after completing 90 minutes of the test. Mean thermal comfort vote. The perceptual thermal comfort response for design was not as pronounced as this measure was for fabric. Yet, Figure 53 suggests that subjects wearing design 3, the ventsuit, perceived greater discomfort than the subjects wearing the other two design variations. Also, those wearing the coverall design indicated the least dissatisfaction with the thermal environment, and those in the jeans assembly expressed feelings of discomfort between the other two designs. Thermal sensation. Figures 54 and 55 show subjects‘ responses to the thermal sensation ballot for the two highest categories, 8 (hot) and 9 (very hot). Notice in Figure 54 (for fabric) the clear increasing number of individuals wearing fabric 1 who felt that they were "very hot.“ Few subjects wearing either fabric 2 or fabric 3 160 a C1 31 ll] (K D 1‘ F 1” ‘Y golf-a-J'T‘fl‘l” ulo 0. X It] 1.. O-l a X Fabric l M 3 Fabric 3 a El Fabric 2 3 1 1 1 1 1 1 1 1 1 0 10 20 30 40 50 50 70 80 90 TIHE [HINUTESI Figure 50.--Mean rectal temperature for design l, the two-piece jeans assembly. l6] Q N 21 8- O 0. mo! m 3 1 1. m ' / m’°- _ _.4{ mo 1-4”‘\\ 1’ ‘ 0. ,’ if X if u: 1. m— 0 ¥ Fabric 1 Pg g Fabric 3 o m Fabric 2 3 1 1 1 1 1 1 1 1 1 0 10 20 30 40 50 60 70 80 90 TIHE (HINUTESI Figure 5l.--Mean rectal temperature for design 2, the coverall. TEMPERQTURE 162 X Fabric 1 3 Fabric 3 m Fabric 2 D913 l l I l 10 20 30 40 50 60 70 00 TIME lfllNUTES) 23.. Figure 52.--Mean rectal temperature for design 3, the ventsuit. Mean Thermal Comfort Votes 163 3% Fabric l o.’ [I] Fabric 2 'l ¢ Fabric 3 ...‘ -' 1 1 tr’1 2 3 4' SI 75 TIME Figure 53.—~Mean thermal comfort vote by design. F 164\ .mep Lm>o uwgnmm an we; Agm> Lo we; mcvuo> muummnsm mo Lonszzuu.¢m mgzmwm m gagged N opened _ U_Lnaa o m e m N o m a m N o m a m N mo__am po__mm AN - m m.w U.0 6|: AS mm r AF. 2 H3 Wm. T m_ m ascend N ascend _ became m m e m N o m a m N o m a m N o W. A. .m We IL." MS Hm - o_ m.w. 1.. S - m_ 165 .meww Lm>o cmwmon An yo; Agm> go we; mcwpo> mpomhnzm we Langszlu.mm mgzmwm pwsmpcw> FFmLm>ou wumwa-N m m w m N o m w m N NOFme po__@ 0 1 m 1 OF 1 m— uwzmucw> FFmLo>ou wumwauN o m w m N o m ¢ m N m m w m N 10H KJBA 5u110A 10H 6U110A snoarqns JO 'ON sloafqns 40 'ON (-166 . specified the "very hot" category as describing their thermal sensa- tion. Many of them chose category 8 instead. The results presented for design, shown in Figure 55, do not show any definite pattern. Summar The dependent measures graphed over time strongly suggested that those subjects wearing fabric l experienced elevated mean tem- peratures (especially skin temperatures) and also perceived themselves to be hotter and in greater discomfort. The temperature and the per- ceptual data for fabrics 2 and 3 demonstrated a similar consistent pat- tern. Lower temperature data and lower thermal comfort (lower value indicated greater comfort) and sensation data were observedikn‘subjects wearing fabrics 2 and 3. In some cases, a decreasing trend over time was readily apparent for these two fabrics, indicating evaporative and/ or convective cooling taking place. Clearly, the physiological and per- ceptual data presented documented that subjects wearing protective fab— ric 2 experienced similar comfort levels as those given fabric 3, while those assigned protective fabric l exhibited greater discomfort. A clear, consistent pattern was not observable for the depend- ent measures by design. The temperature data showed a trend toward the highest temperatures being reported for design 3, the ventsuit. This was especially true with fabric 1. It was theorized that a panel of synthetic fabric would promote evaporative and convective cooling of the back. However, only l00% cotton mesh was available at the time of the experiment. The cotton mesh absorbed perspiration 167 (data to be presented in the next section), causing the panel to cling to the back, most likely increasing perceived discomfort. The panel, laden with sweat, may also have added to the metabolic cost of the planned physical activity. Recalling that jeans and a chambray shirt were specified to represent what was commonly worn by the grower, graphs of the depend— ent measures for this fabric/design combination were prepared on acetate sheets. This was done to visually compare the results for this cell with the results for the two protective fabrics and the various design variations. This visual examination demonstrated similar data for the control and fabric 2 and considerable differences between the control and fabric l. To determine if these observed effects were statistically significant, analyses were performed and the results are given in Phase 2 of this chapter. Phase 2 This section of the findings was partitioned into five sub- sections. The first three subsections cover the statistical treatment of the major dependent variables for fabric and design. Subsection l addresses the thermal sensation votes, subsection 2 explores the data gathered for percentage of sweat that evaporated, and subsection 3 presents the MANOVA results for the set of three dependent measures treated as related aspects of a single response. The results of the chi-square analyses for the two summary variables, anticipated comfort and willingness to wear protective clothing, are given in the fourth l68 subsection. The final subsection summarizes the results of the data analyses. Thermal Sensation Votes As indicated by Figures 54 and 55, which depicted the fre- quency of thermal sensation votes by fabric-design over time, a definite clustering of votes at the upper end of the scale was apparent. For ballot six, four categories were selected by the subjects to describe their perception of the warmness of their environment, with 1 over half of the subjects choosing category 8 (hot). Thus, categori- ) cal analysis of the data was deemed appropriate rather than analyti- 1 cal procedures which relied on the dependent measure being interval data. The categories 6 and 7 were combined, and two 3 x 3 chi-square analyses were performed to determine if thermal sensation response was independent of fabric and design. Two separate analyses were carried out because if the data were broken down for a three-way cross— tabulation, such as is used in log-linear models (see Everitt, 1977), the data would be too sparse. The frequency of the sixth thermal sensation vote by fabric, given in Table l2, indicated that subjects wearing fabric 1 responded higher on the scale than subjects wearing the other two fabrics. Note that similar responses were given by subjects wearing fabrics 2 and 3. The observed data do not suggest independence, and this was borne out by the chi—square analysis. With 4 degrees of freedom, x2 = ll.00, which was statistically significant at the .05 level. M / if l69 Table lZ.--Frequency of the sixth thermal sensation votes by fabric. Thermal Sensation Votes . Column Fabric Warm and Slightly Warm Hot Very Hot Total Fabric 1 l 7 l0 l8 Fabric 2 4 ll 3 18 Fabric 3 4 l2 2 l8 Row total 9 30 l5 54 X2 = ll.0 with 4 df, p < .05. The frequency of thermal sensation votes for design (Table 13) do not indicate a clear-cut pattern, although these data do support the trend that those wearing design 3, the ventsuit, considered them— selves hot and perceived thermal discomfo rt. With 4 degrees of free- dom, x2 = 6.866, which was not statistically significant at the .05 level. Table 13.--Frequency of the sixth thermal sensation votes by design. Thermal Sensation Votes . Column 09519" Warm and Total Slightly Warm H°t very H°t 2-piece assembly 4 l0 4 l8 Coverall 5 7 6 18 Ventsuit 0 l3 5 18 Row total 9 30 15 54 X2 = 6.866 with 4 df, p < .05. l70 Percentage of Evaporated Sweat During exercise in a warm environment there is the danger of heat build-up. Vasodilation and the usual increased skin temperature is one of the body's responses as it seeks to maintain thermal equi- librium. This response has been illustrated in a preceding section. However, sweating is another primary mechanism of the body to dissi- pate heat. In order to be effective as a means of ridding the body of excess heat, evaporation of the sweat must take place. Therefore, the volume of sweat secreted and the percentage of that which is evaporated are important determinants of a person's thermal well-being in a heat—stress environment. The presence of clothing can seriously impede evaporation. As Fourt and Hollies (1970) pointed out, clothing is not merely a passive skin covering; rather, it interacts with and modifies the heat-regulating function of the skin. Body movement further impacts on the effects of clothing. Figure 56 diagrams the clothing assembly and air layers that formed level one of the human-constructed environ- ment for each test subject. Typically, a thin air space, the size dependent on the design and fit of the clothing plus air and body movement, separates the various garment layers. These layers of air and fabric add to the resistance of heat and moisture transfer from the body which was at a higher temperature than the environmental chamber (the arrow in Figure 56 indicates the direction of heat and moisture flow from the body through air and fabric to the environment). 171 . 8F???“ . ‘ *Air. Film f:_l/y Outer Carment -. -._.5) i 'l' Underwear Wflffl/ sf,“ W732 Figure 56.--Diagram of the skin, the HCE], and the direction of heat and moisture transfer. The physical properties of fabrics strongly impact on heat and moisture transfer. But the literature suggests that the effect of design on heat and moisture transfer is less conclusive. The advantage of wetting out of a garment to facilitate evaporative cool- ing has been documented. Recognizing the vital role that sweat production and evapora- tion play in fostering thermal well-being, data on this phenomenon were sought. Unfortunately, due to measurement imprecision, these data should be considered as crude approximations of the phenomenon under investigation, and as such should be viewed as exploratory in nature. The test clothing varied in its ability to hold and transfer moisture. Table 14 presents the clothing weight change in grams. The change reflects moisture either absorbed (into the fiber, yarn, or fabric structure) or adsorbed (retained on the surface area of (.1732 - fibers, yarns, or fabric structure) in all_of the test clothing provided. A subject's underwear, socks, and test garment were weighed together and the data separated by fabric and design of the outer garment. Table l4 clearly shows a dramatic difference for clothing weight change. Fabric l showed a greater weight gain than fabrics 2 or 3. This moisture collected on the inside of the garment to the point of run-off. This problem contributed to the measurement error. Table l4.-—Mean clothing weight change in grams for fabric and design. . 09519" Fabric Fabrl C 2-Piece C 1] V t _ Mean TOta] Assembly Overa en SUlt Fabric 1 291.467 335.917 488.867 372.083 Fabric 2 118.217 39.l83 43.6l7 67.006 Fabric 3 273.500 159.717 232.100 221.772 ”9519" mean 227.728 178.272 254.86l totals Design 1, which included denim jeans, showed substantial weight gain as would be expected due to cotton's ability to absorb moisture. Fabric 2 showed relatively little weight gain compared to the other fabrics. Subjects wearing fabric 2 either didn't sweat as much as the other test subjects or they were able to evaporate a greater quantity or a combination ofthe two. The presence of the 100% cotton panel in the ventsuit likely contributed to the elevated weight changes shown by this variation. _l73 The method of determining volume of evaporated sweat yielded over-estimates; it more accurately reflected sweat that wasn't absorbed or adsorbed in the clothing. Thus, these data should be studied only relative to each other for fabric and design. Table 15 reports the data computed for mean percentage of evaporated sweat by fabric and design. Looking at these data by fabric, one notes that those wear— ing fabric 2 experienced the highest percentage evaporated sweat and those in fabric 1 showed the lowest percentage. The presence of the two—piece jeans assembly improved the over—all fabric 1 mean. It was interesting that fabric 2 showed greater evaporative power than fabric 3. Interpretation of these data demands caution, yet, despite the over-estimate, a consistent pattern was apparent. This trend sug- gested that evaporation was enhanced with use of fabric 2, and perhaps more so than fabric 3 (chambray). If indeed this was occurring as the data seem to suggest, this evaporation would have had a cooling effect on these subjects. The skin temperature data for fabric 2 do indicate cooling taking place. No trend was observed for design. Table 15.--Mean percentage evaporated sweat by fabric and design. Fabric 2 P. Des‘g" Fabric Mean - 1ece - Total Assembly Coverall Ventsu1t Fabric 1 69.56% 59.15% 52.86% 60.52% » Fabric 2 86.51% 93.52% 93.69% 91.23% Fabric 3 74.49% 85.16% 76.52% 78.72% Desjg“ mean 76.85% 79.28% 74.35% totals l74 Rectal and Weighted Skin Tempera- tures, Thermal Comfort Responses The thermal comfort literature repeatedly echoes a theme that an individual's thermal response to the environment has multiple facets. Therefore, the assessment of a person's thermal response should include both physiological and perceptual assessments if the researcher is to tap that multidimensional aspect of thermal comfort. The present experiment was planned and conducted to enable evaluation and comparison of physiological and affective criterion measures of rectal temperature, weighted skin temperature, volume of sweat secreted and percentage evaporated, thermal sensation, and thermal comfort. Two of the dependent measures, as previously noted, required a separate statistical treatment even though they were logically part of the same response. Unfortunately, due to a problem in measurement precision, only crude approximations of percentage of evaporated sweat could be obtained. Recognizing the deficiency of these data, the investigator chose to statistically analyze this variable by itself. The clustering of the second measure, thermal comfort responses, sug- gested that a statistical technique for categorical data might be more appropriate than a technique which required that the dependent meas- ures have at least ordinal properties. Thus, even though all five dependent measures were related logically and theoretically, only three were selected as the set of dependent measures to be tested as a single response for fabric and design using multivariate statistical analysis. The use of multivariate techniques is predicated on the notion of "multiple causes" or "multiple outcome variables" that are 175 conceptually meaningful to describe and analyze a phenomenon of interest. Finn (l974) stressed that fin every case, it is critical that the variables of any set share a common conceptual meaning, in order for the multivariate results to be valid" (p. 4). Positive intercorrelation between dependent measures is not in itself a suf- ficient criterion to designate dependent measures as a ”meaningful set" (Finn & Mattsson, l978). Multivariate models offer the advantage that if conceptually related measures are intercorrelated (often moderately to highly intercorrelated) or have different variances, the analysis is not invalidated (Finn et al., 1978). Instead, a set of arbitrary vari— ances and intercorrelations is assumed in the model, estimated from the data, and can be used for interpretation and inference. For this study, a multivariate two-way analysis of variance with three levels of each independent variable was used to test group means on three intercorrelated variables simultaneously. The purpose of the analysis was to investigate mean differences among fabrics and designs on rectal temperature, weighted skin temperature, and per- ceived thermal comfort. The two-way fixed-effects analysis—of—variance model was: yijk = Ll + (11+ Bj + (a8)jk + Eljk (5) where: i = 1,2,3 3 = 1,2,3 k = l,2,...,6 176 In equation (5), u represents the grand mean, the 0's and 8's represent fabric and design effects, respectively, while the (dB)'s connote the interaction effects of fabric and design. The model assumes that eijk are independent and identically distributed normal random variables with a mean of O and a common variance of 02. Therefore, each observed cell variance (s..2) is an independent esti- lJ mate of 02 with degrees of freedom equal to 5, i.e., (6—l). The pooled variance estimator,sz, is used to estimate 02 with 45 degrees of freedom (i.e., 9 cells x 5). Tables l6, l7, and 18 give the observed cell means for the nine cells for each of the dependent measures. Examination of the three tables by fabric showed a consistent trend. Higher temperatures and greater perceived thermal discomfort were characteristic of fabric 1. Fabrics 2 and 3 showed similar mean values for the three dependent measures. However, for design a distinct pattern could not be discerned. Little variation is apparent for weighted skin temperature. Tables l7 and l8 suggested that higher rectal temperatures and greater perceived thermal discomfort were associated with the ventsuit design. Before proceeding with the MANOVA analysis, the cell standard deviations (Table 19) were examined. Recall that MANOVA does not assume homogeneity of variance across dependent measures. However, the variances for a given dependent measure are assumed to be homo- geneous. Thus, for example, the variances for rectal temperature should not vary significantly from one cell to another, but they can be quite different from the variances for thermal comfort. Since 177 Table 16.—~0bserved cell means and combined means for weighted skin temperature. Design F b . Fabric _ - .a r1c 2 Kggggbgsans Coverall Ventsuit Combined Means Fabric 1 95.8367 96.4517 97.5133 96.601 Fabric 2 93.7667 93.2883 93.7400 93.598 Fabric 3 93.3383 83.6800 93.5583 93.526 Design combined means 94.314 94.473 94.937 94.575 = ggggd Table l7.--0bserved cell means and combined means for rectal temperature. Fabric 2 p' J 09519” Fabrifi - 1ece eanS - Combined eans Assembly Coverall Ventsu1t Fabric 1 99.7700 99.8900 100.7583 100.139 Fabric 2 99.7867 99.8117 100.0467 99.882 Fabric 3 99.7717 99.6433 99.7000 99.705 Design = grand combined means 99.776 99.782 100.168 99.909 mean there were equal cell sizes, the Hartley test (Neter & Wasserman, 1974) was used to test for homogeneity of variance. Since this assumption was met, a multivariate extension of the usual F-test was used to test Hypotheses 1-3, 5-7, and 9 listed in Chapter I. 178 Table l8.--0bserved cell means and combined means for thermal comfort responses. Design Fabric P' Fabric Z'Aggggbggans Coverall Ventsuit C0mb1"9d Means Fabric 1 51.1667 54.8333 56.5000 54.17 Fabric 2 51.8333 46.1667 49.0000 49.00 Fabric 3 47.0000 44.0000 51.0000 47.33 ”9519" 50.0000 48.3333 52.1700 50.17 = grand combined means mean Table l9.--Cell standard deviations for rectal temperature, mean skin temperature, and thermal comfort. Std. Dev. for Std. Dev. for Std. Dev. for Fabric Design Rectal Weighted Skin Thermal Temperature Temperature Comfort 1 2-piece .361 .543 9.988 1 coverall .653 .173 8.931 1 ventsuit .348 .187 7.556 2 2-piece .242 .190 6.940 2 coverall .015 .970 9.538 2 ventsuit .526 .145 5.692 3 2-piece .692 .972 7.563 3 coverall .354 .343 11.645 3 ventsuit .406 .910 6.164 A summary of the results of the MANOVA analysis is presented in Table 20. interaction indicated no statistical significance. Examination of the multivariate F for fabric and design Therefore, we 179 were able to proceed with the test of significant differences among means for the three levels of design. The multivariate F of equality of mean vectors for design was 1.44 with degrees of freedom of 2 and 45, which was not significant. The multivariate F for fabric equalled 14.07, which was highly significant at the .0001 level, with 2 and 45 degrees of freedom. Thus, there wasa significant effect of fabric on the set of dependent measures. Tab1e 20.--Summary of analysis of variance for thermal-analysis study. Tests of Significance Source of MU;E;:?E;:te Univariate F-Values Variation Rectal Weighted Thermal df F p*** Tem Skin Comfort p. Temp. Response Constant l -- -- Fabric 2 14.07 .0001 2.75* 55.74** 3.22** Design 2 1.44 .2098 2.91* 1.90 .94 Fabric & design 4 1.07 .3942 1.57 1.53 .71 interaction Mean sq. error 45 .312 .994 71.00 Pooled std. dev. .559 .997 8.43 Total 54 *Significant at p < .10. **Significant at p < .05. ***These are exact alpha levels. 180 The multivariate test statistic is used for an initial deci- sion about the null hypothesis. Once this test statistic has been found significant, then it is appropriate to examine the set of uni- variate results computed by the Multivariance program. These F-ratios are the results that would have been obtained if each dependent meas- ure had been considered in isolation in a simple one-variable analysis. Since the dependent measures are intercorrelated, the univariate F-statistics are not independent of one another. However, they do have interpretive value. Clearly, weighted mean skin temperature, which was most affected by fabric, was primarily responsible for the significant effect. Rectal temperature and thermal comfort also con- tributed to the significant effect. It is important to note that because the multivariate F for design was not significant, the univariate results were not discussed. Without the protection of a significant multivariate F-test, separate univariate decisions are suspect since statistical error rates are likely inflated (Finn et al., 1978). From Table 16, which presents the observed cell means for weighted skin temperature, the data clearly suggest that fabric 1 was significantly different from the second protective fabric and from fabric 3, thus being the contributor for the significant MANOVA fabric effect. Since the weighted skin temperature data for fabrics 2 and 3 were so similar, and because fabric 3 was originally chosen as a control, univariate confidence intervals were constructed to estimate the magnitude of the difference between fabric 1 and fabric 3 for the three dependent measures. Table 21 presents the 181 results of this post-hoc procedure. The interpretation would be that the difference between fabrics l and 3 for weighted mean skin tempera- ture, for example, would be in the range from 2.4 to 3.75. Table 21.--Confidence intervals for the difference in effect of fabric 1 and fabric 3. Estimated Effect Standard 95% Confidence Interval 3:5?gg$2t of Differences Error of for True Difference in 0‘1 ' 0‘3 a] ' 03 Effects, a] - a3 Egmpglature ‘4344 -185 ~06 to .81 121.323.23.35" 3-075 .332 2.40 to 3.75 12;?flil 6.833 2.809 1.16 to 12.51 df = 45 Summary Questions At the completion of the experiment, the subjects were asked to respond to two summary questions. The first requested that the subjects evaluate their experienced comfort versus their anticipated comfort for the test garment that they had been assigned. The find- ings for this variable by fabric are given in Table 22. Although very few subjects found the test clothing goglgr_than what they had antici— pated, it was interesting that almost all who did were wearing fabric 2. 0f the 24 students who found their assigned clothing warmgr_than they had expected, over 70% had worn fabric 1. 182 Table 22.--Cross-tabulation for anticipated comfort by fabric. Anticipated Comfort Fabric About the Row Total Cooler Same Warmer 0a 5 12 Fabric 1 0%b C 29.4% 70.6% 17 ( 0% ) (22.7%) (50.0%) 6 7 5 Fabric 2 33.3% 38.9% 27.8% 18 (85.7%) (31.8%) (20.8%) 1 10 7 Fabric 3 5.6% 55.6% 38.9% 18 (14.3%) (45.5%) (29.2%) Column total (7) (22) (24) 53 x2 = 6.911 with 2 df, p < .05. aIndicates number of subjects. bIndicates row percentage. CIndicates column percentage. Since the expected cell size was less than five in the column labelled "cooler," this column was combined with the column "about the same" before chi-square analysis was performed. Analysis yielded x2 = 6.911 with 2 degrees of freedom, which was significant at the .05 level. As Table 23 indicates, the data for anticipated comfort by design did not suggest a meaningful pattern. When anticipated com- fort was analyzed by design, the null hypothesis of independence could not be rejected. was not significant at the .05 level. With 4 degrees of freedom, X2 = 2.197, which 183 Table 23.--Cross-tabulation for anticipated comfort by design. Anticipated Comfort Design Row Total About the Cooler Same Warmer 3a 7 8 Ventsuit 16.7%b 38.9% 44.4% 18 (42.9%)c (31.8%) (33.3%) 3 8 6 Coverall 17.6% 47.1% 35.3% 17 (42.9%) (36.4%) (25.0%) . 1 7 10 2-p1ece . 5.6% 38.9% 55.6% 18 Jeans assembly (14.3%) (31.8%) (41.7%) Column total 7 22 24 53 x2 = 2.197 with 2 df, p > .05. aIndicates number of subjects. bIndicates row percentage. CIndicates column percentage. Willingness to wear the test garments was assessed after informing the subjects that the clothing provided protection against harmful chemicals in the workplace. The frequency of responses for this variable by fabric is shown in Table 24. 0f the 54 subjects responding, only two would be unwilling to wear the protective cloth- ing. Examination of the remainder of the responses indicated a modest trend. Almost 56% of the subjects wearing fabric 1 were either unwill- ing to wear the garment or willing, only if required to do so. A modest 16.7% indicated that they would be willing to wear fabric 1 under environmental conditions similar to the test. This percentage willing to wear the test clothing under similar climatological 184 conditions increased to almost 39% for those wearing fabric 2 and 50% for those given fabric 3. A reverse trend was apparent for those subjects who responded that they would only wear the clothing if required, as shown in Table 24. It is important to emphasize that these findings are not generalizable to a larger population. At the planning stages of the experiment, the investigator recognized that a myriad of factors impact on an individual's willingness to wear protective clothing. These data were collected to gain possible insights and to facilitate comparison with future field data. Before chi—square analysis was used to test for independence, column 4 (not willing to wear) was combined with column 3 (willing to wear only if required). Results of the analysis indicated x2 = 4.83 with 4 degrees of freedom, which was not significant at the .05 level. The data for willingness to wear the test garment by design are displayed in Table 25. Of the subjects wearing the ventsuit, almost 39% indicated that they would be willing to wear the gar- ment under environmental conditions similar to the test. Recall that although a consistent pattern did not emerge for design in the data presented in the Phase 1 findings, yet there was a tendency for those wearing the ventsuit to exhibit higher temperatures and to perceive greater discomfort. This was most apparent for those in fabric 1. Recognizing this, further information regarding the fabric worn by these subjects was sought. 0f the seven subjects willing to wear the ventsuit under similar conditions, one wore fabric 1, three .mmmucmogma :Espou mmpmowwcHu .mmmpcmogwa 30L mmpmuwucHn .muomnnzm 40 Logan: mwpmownch .mo. A a .45 a 58?; mm.5 u ax 185 em N ON mp mp repop :Es—ou o ANo.va ANw.omv AN5.N4V m_ o Nm.NN NN.NN No.0m m cwcaac o m 4 a ANo.omv ANo.omv ANN.ONV “Nw.cmv w_ Nc.m Nm.mm NN.NN No.8m N cwcaaa _ c a N No.0mv ANo.mav ANm.va cANm.mPV w_ Nc.m No.om NN.NN DNN.8_ _ cvcaaa _ m m am , pme on... cam: 58 am co 58 comm cage 8884 Peach mcwpfivz cmngcmm cw mm: .asmh m? szwmawmowwwmmou 36m 882 cam: op mchpcz c863 6» mcwp_23 cam: 08 mappprz 8_cnaa mcwgpopo pmmp Lomz op mmmcmcw—sz .u?cnm$ >3 mcvzpopu w>wpumpoca Low; op mmmcmcwppvz com cowumpzncpimmogu-i.¢m m_nmh 186 .mmmpcmugwa 20L mmumuvvcH .mmmpcmugma caspou mmpmuwvcHo n .muomwnzm mo Longs: mmpwowvcHw .mo. A 8 .cc 5 :62; ¢.N 1 «X am N ON NF m_ _8856 caspoo ANo.omV ANO.ONV ANm.mmv ANF.N¢v m_ Nc.m NN.NN NN.NN N5.5¢ »_aeammmow”mwh _ a m m . N ANo.omv ANo.omV ANm.mmv AN_.PNV w_ N8.m Nm.mm Nm.mm NN.NN _Faca>ou _ 8 N a o ANo.omv ANN.NV ANw.cmv N_ o Nc.mm No.m 8N5.mm bwzmb=a> o o_ _ 8N “mac on cam: 88 cm on as comm gasp 888; _aboc mcwp_23 eacwzoam a? was .aecc cw _8=cmswmowwwmmou mewspopo pmmp Law: ow mmmcmcw__w3 .cmwmmu zn mcwgyopo m>wpumpoca Lew: op mmmcchFFTZ com covapsnmuimmOL01i.mN wpamh 187 wore fabric 2 and three wore fabric 3. Evidently one subject who wore the fabric 2 ventsuit either did not find the situation thermally burdensome or he perceived the dangers from hazardous chemicals to outweigh the discomfort. There were two other subjects who wore fabric 1 and yet were willing to adopt the garment for use under similar conditions. Both of these subjects, however, wore design 3, that is, the fabric 1 shirt and the denim jeans. Further examination of Table 25 did not suggest any over-all trends. Chi-square analysis with columns 3 and 4 combined gave x2 = 7.4 with 4 degrees of freedom, which was not statistically sig- nificant at the .05 level. Summar The phase 1 graphical representation of the dependent measures over time clearly indicated that elevated temperatures and greater perceived thermal discomfort were associated with fabric 1, the spun- bonded olefin fabric. Similar data, both physiological temperature data and perceived thermal comfort and sensation, were observed for fabric 2 (the three-layer laminate) and fabric 3 (chambray). Many of the temperature graphs for fabrics 2 and 3 indicated an over-all decreasing trend over time. This was in marked contrast to fabric 1. No clear-cut patterns were apparent for design, although the data suggested that higher temperatures and greater thermal discomfort were characteristic of design 3 (the ventsuit), especially when con- structed in fabric 1. 188 The second phase of the data treatment focused on hypotheses testing. The hypotheses tested, the methods of analyses, and the results are summarized in Table 26. Examination of the table shows that none of the hypotheses for design was rejected, whereas all of the hypotheses for fabric except willingness to wear were rejected. Mean rectal temperature, mean weighted skin temperature (time = 90 minutes), and the thermal comfort votes (sixth ballot) were treated as a sgt_of conceptually related dependent measures that represented different facets of a single response. As such, multivariate statis- tical techniques were used to test Hypotheses 1-3, 5-7, and 9. The MANOVA results indicated that mean differences in the dependent meas- ures for fabrig_were significant at the .0001 level. Mean weighted skin temperature strongly contributed to this statistically significant finding. There were no significant differences detected for design at the .05 level. Confidence intervals indicated that the three depend- ent measures for fabric 1 were significantly different from those measures for fabric 3. Thermal sensation votes, which were in general clustered at the upper end of the nine-point scale, were highest for subjects wear- ing fabric 1. As Table 26 indicates, results of the chi-square test of independence for thermal sensation and fabric (Hg) did not support independence. The null hypothesis for design (Hg) could not be rejected, however. Unfortunately, measurement error was a problem for data gathered to investigate the percentage of evaporated sweat. There- fore, means and standard deviations were computed solely for 189 pumnmc . . x mocmvcwawucw co cmwmmn No pcmucmawvcw op umpwmu mo A mm ouN pmmu memscmiwgu ace mmpo> coapmmcwm FmEngg cam: .w pomwmg mo.A cm. um .>P:: .mmao> pgowaou Fmsgmzp came x3 68 capvaa ON.A aaa._ua .ppsz <>ozw:: .mczwmcmaemp Fmpomc cams ac ua_wma ON.A raa._ua .c_=z <>ozvc: weapmgmaemu :wxm umpsmwmz cams zn ac 88—waa ON.A 455._ua .ppsz <>oz cowpmmcmm Pmscwcp new: .3 mo.v NN.m um .>w:: mmgo> peoNEoo Foggmca cums bacham _o.v No.a_ua .p_:z <>ozw:= mczpmgqump Pwuomg cams pomnmm _o.v no.8Fuu .szz <>ozm:: weapmcmgemp :me cmugmwmz cams pumnmm Fo.v No.3Fuu .ppzz <>oz64 ovpmwumpm pmwp :owmwomo . mczumuocm umpmmp mwmmcpoqz: szz cccmwm 6;» Lo a=Fa> Fauwbmwbapm .mowpmepwpm mepcmgm$cw co mppzmwc co mpnmp acceszmii.oN mpamk 190 .AwmmF ..Fo pm ccpzv oopoFWCW mo hos mopo; Locgo —ooppmppopm oocpm =pooom=m= mo oozop> ogo mppzmog opopco>pcz opoeoomm ozp .z opopco>ppF=E pcoopmpcmpm o psozppza powwog . . 1 x oocmocwooocp mo :mpmoo 4o pcoocwooocp mo: mcpzpo—o op omppoz mo A z N1N poop ocozom1pzu m>ppoopoco Loo: op mmocmcp_pp3 .mp poonog . . 1 x oozmocoooocp 4o upcoom 4o pcoocoooocp mo; mcpzpopo op cuppa; mo A mm ¢1N pmop mgozom1pzo o>ppoopoco Loo: op mmocmch—pz .qp powmog . . 1 x mocoocwooocp mo :mpmoo wo op oonoz mo A N N1N poop ocosom1pzo pcoocoooocp mo: pgomaoo oopoopoppc< .m_ . . 1 mocoocoooocp co upcoop co powwoz mo v _m o1Nx poop ocosom1pzo pcoocwooocp mo: pcopEoo oopoopoppc< .Np Locgm pcosogzmooe poozm oopocooo>o mo pcmogoo op woo oopmop poz zo oococowmpo :mpmoo pcoopppcmpm oz .Fp Loggo pcoEocsmooE pow3m topogooo>o wo pcoocwo op moo oopmop poz zo mococopppo upcoow pcoopmpcmpm oz .0— poonw; . . 1 :mpmoo oco oppoop op oo—poz om A no _1z <>ozoz oppmppopm pooh copmpooo . ogzowoocm oopmmh mpmozpooxz szz cpcopm asp co aspa> _aoppmppapm .Umchpcoo11.mN anoH 191 exploratory purposes. The null hypotheses H20 and Hg] were not, therefore, tested. Despite the deficiencies of these data, a trend was apparent. Subjects wearing fabric 2 exhibited the highest per- centage of evaporated sweat, and those in fabric 1 the lowest per- centage. Investigation of the moisture adsorbed or absorbed by the test clothing indicated that the greatest increase in weight was asso— ciated with fabric 1 and the least with fabric 2. This concurred with on-site observation of the investigator at the end of the test sessions. Moisture had collected to the point of run-off on the inside of gar— ments constructed of fabric 1. Anticipated comfort and willingness to wear protective clothing were analyzed using chi-square analyses by fabric and design. The null hypothesis of independence for anticipated comfort and fabric (le) was rejected at the .05 level. Willingness to wear protective clothing and fabric (H24) and the null hypotheses HA3 and His for design could not be rejected at p < .05. Thus, both phases of the data treatment yielded a consistent, unmistakable pattern for fabric. Subjects wearing fabric 2 (three- layer laminate) and fabric 3 (100% cotton chambray) experienced a similar level of thermal comfort, as indicated by both physiological and perceptual measures. Subjects wearing fabric 1 (the spun-bonded olefin) experienced higher temperatures, lower percentage of evaporated sweat,greaterperceived discomfort, and higher perceived thermal sen- sation. Clearly, evaporative and/or convective cooling was taking place for subjects wearing fabrics 2 and 3. When these results are examined in conjunctionwiththe physical characteristics of the test 192 fabrics given in Table 9, implications for the ASTM test methods emerged. Air permeability is frequently used as an indication of the "breathability" of a fabric. Results of the air-permeability testing indicated no air flow through fabric 2 and approximately 190 ft3/min/ft2 through fabric 3, an appreciable difference. Yet, the present study found the thermal response to both fabrics during wear-testing very similar. The data suggest that either air permeability was not a good indicator of "breathability” or that the Gurley Tester did not ade— quately determine the air permeability of fabric 2, or both. Design clearly did not influence thermal response as fabric did. The ventilating panel not only did not improve thermal well- being, but the data suggested that it might have added to the thermal burden. Ventsuits constructed of fabric 1 showed an increased post- test weight that was markedly higher than any other combination. Most likely as the panel became saturated with sweat, the panel clung to the undershirt and both probably hugged the back, thus eliminating air spaces between the clothing layers. This could well have con— tributed to the perceived increased discomfort recorded by subjects wearing this test garment. CHAPTER V SUMMARY AND CONCLUSIONS This chapter has been organized to cover four topics. First, a summary of the thermal-analysis study and the context within which this study was conducted is presented. Second, the limitations of the study are identified. The enumeration of the limitations offers a prelude to the two concluding sections of the chapter, implications of the study and recommendations for future research. Summary Agricultural pesticide usage has continued to increase. California alone doubled its usage of pesticides to more than 111 million pounds, between 1974 and 1977 (Doutt, 1979). The Environmen- tal Protection Agency has been charged with a variety of monitoring, standard-setting, and enforcement activities related to the usage of pesticides. Both acute and chronic adverse health effects continue to be documented for agricultural workers occupationally exposed to pesticides, despite efforts to reduce the hazard through elimination of toxic pesticides, the establishment of "safe" reentry periods, and the installation of various health and workplace monitoring systems. Pesticide poisoning incidence data are difficult to obtain, and various approaches have been tried by different countries. However, the World Health Organization estimates that approximately 500,000 193 IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII!”“”‘""‘““”"EM 194 cases occur annually worldwide, with about a 1% fatality rate (Davies & Enos, 1980). The use of protective clothing has been recommended to reduce workers' dermal exposure to pesticides. 0f the three routes of pesti- cide entry into the human body (i.e., respiratory, dermal, and inges- tion), dermal exposure is considered the primary mechanism (Hanset et al., 1980; Taylor et al., 1978). Protective clothing is one strategy for reducing dermal exposure that is applicable for all of the major categories of workers occupationally exposed to pesticides. However, the clothing which has been designed to provide protection is unacceptable to many of the individuals who have been shown to need it most. Emphasis has been directed toward finding an impermeable fabric, rather than an examination of the whole problem. Attention has not been focused on the issue of thermal comfort of agricultural workers toiling in a hot environment, a problem which contributes toward lack of user acceptance. In the fall of 1978, Jacquelyn Orlando De Jonge, Ph.D., then Associate Professor in the Department of Human Environment and Design, Michigan State University, currently Head and Professor of the Depart- ment of Textiles, Merchandising and Design, University of Tennessee, initiated a major research investigation aimed at limiting the dermal exposure of the independent fruit grower to pesticides, while main- taining acceptable thermal-comfort levels through the development of functionally designed protective garments. Although the major focus of the study was directed toward Michigan fruit growers who apply pesticides by air—blast spray methods, the protective clothing being an... - “W ‘1 195 developed would be appropriate for a much larger population as well. This research has been supported by the Michigan State University Agricultural Experiment Station and the North Central and Southern Pesticide Impact Assessment Programs. The present study, one component of this over-all research project, was undertaken to evaluate the thermal response of subjects wearing selected protective fabric/design combinations under controlled environmental conditions simulating Michigan summer weather condi- tions. This study was conducted at the Institute for Environmental Research at Kansas State University, a facility that permitted the monitoring of the subjects' physiological responses while controlling environmental variables at prescribed levels. An ecological perspec- tive served as the framework for this study. Dependent Variables Thermal response was assessed by weighted mean skin tempera— ture, rectal temperature, percent of evaporated sweat, and perceived thermal comfort and thermal sensation. Data on willingness to wear protective clothing and anticipated comfort were also obtained. Independent Variables Three fabrics whose characteristics as barriers to pesticide penetration were known were selected for evaluation. Fabrics 1 and 2 had been shown to offer excellent resistance to pesticide penetration in an earlier phase of the total research project (Orlando et al., 1981). Fabric 3 had shown poor resistance to pesticide penetration in the same study cited above, but was selected since it is frequently 196 now worn by the grower for pesticide application. Fabric 1 was a disposable polyethylene-coated 100% spun-bonded olefin fabric. Fabric 2 was a three—layer laminate construction consisting of an outer woven ripstop 100% nylon/a thin microporous polymeric film of polytetrafluoroethylene/and an inner 100% nylon tricot. Fabric 3 was a woven 100% cotton chambray shirting fabric. The physical charac- teristics of the test fabrics are given in Table 9, Chapter III. Three design variations were specified. Design 1 included a long-sleeved traditional—styled shirt and denim jeans. Only the shirt fabric was varied in the three test fabrics. This procedure enabled examination of the thermal response associated with a protective gar- ment that was a partial body covering. This was a serious concern since only limited data were available on which areas of the body received pesticide deposition during actual field spray operations. The combination of denim jeans and fabric 3 represented what was commonly worn by the grower for pesticide application. Designs 2 and 3 were both coverall designs, developed to cover areas of the body anticipated to be areas of high pesticide deposition. In addition to pesticide protection, other needs of the growers, including movement, thermal comfort, and safety from farm accidents, influenced the development of designs 2 and 3. Figures 11, 12, and 13, Chapter III, illustrate the three design variations. Controlled Variables Because the focus of the study was on evaluating the sensa- tion of thermal comfort and the accompanying physiological measures 197 associated with wearing selected garments, numerous variables which impact on thermal comfort had to be controlled. In using an ecologi- cal framework, these variables were organized into those relative to the human environed unit (each test subject), the human behavioral environment (the researcher and other test subjects present in the chamber with the HEU), and the human constructed environment—-level 2 (climatological conditions within the test chamber). The controlled variables are given in Table 27. Table 27.--Summary of controlled environmental variables. Variable Control Specification Age 18-25 years Sex Male Psyche Random assignment Human Body type All wore same size garment Environed . . . . . . . Unit Phy51cal condition Phy51cal exam1nat1on required Food/drink intake Standard breakfast provided Physical activity 3 mets Exposure time 30 min preconditioning, 2 hr exposure Dry-bulb air temp. 85°F Human Mean radiant temp. 85°F Constructed Relative humidity 60° Env1ronment2 Air movement Still air (.15 m/s) Human . . . . . Behavioral Verbal 1nteract1on Discuss1ng test cloth1ng and Environment between subjects test conditions not permitted 198 Experimental Design and Sample A 3 x 3 complete factorial experimental design with six repli- cations was used. Fifty-four male students, attending Kansas State University, served as test subjects. The students were recruited through newspaper advertisements and were required to pass a physical examination before being accepted as a test subject. Each qualified test subject was expected to wear ppp_test garment for ppg test ses- sion and was paid for his participation. Twelve test sessions of two—hour duration were held in a six-day period in the spring of 1980. Between two and six persons constituted a test group. All testing was done in the morning. Test Protocol All test subjects were fed a 600-calorie (20-25 g protein) breakfast the morning of their scheduled test. Following breakfast, the subjects reported to the pre-conditioning room at the Institute for a 30—minute orientation. After the procedures were outlined to the students, test clothing, consisting of the experimental garment, white socks, jockey shorts, and undershirt, was issued to each subject. They were instructed to change their clothing, insert the rectal probe, put on the heart-monitoring harness, and then to return to the pre-test room. When they returned, skin thermistors were taped to each subject with micropore surgical tape in three locations: the right pectoral region of the chest, the radial surface of the left arm (or right arm if the individual was left-handed), and the fibular sur- face of the left leg. A pre-test weight of each subject was taken. 199 The subjects then entered the test chamber. In order to simulate the work accomplished in applying pesticides using a tractor, an activity pattern was established. A nine—minute rest period was followed by six minutes of walking up and down steps to a specified cadence. This pattern was continued for the two-hour duration of the test. The students were free to read or to speak to each other through- out the test, with the restriction that they not discuss the experiment. A thermos jug of water was provided for each student, and they could drink if they chose to. During the eight rest periods, the subjects completed two ballots, a nine-category thermal sensation scale, and a nine-category semantic differential comfort scale. Both ballots were collected after each vote. Skin temperature and rectal temperature were moni- tored in a control room located near the test chamber throughout the test. A subject whose rectal temperature rose 2°F was removed from the test. Heart rate was monitored by the test subjects for safety reasons and not for analysis. A registered nurse was present through- out the experiment. Upon completion of the test, subjects were disconnected, taken to the pre-conditioning room, and weighed. Monitoring devices were removed, subjects changed their clothing, and they returned to the pre-conditioning room to complete two summary questions. Students, after being informed of the protective characteristics of the clothing that they had been wearing, were asked to indicate their willingness to wear such clothing. Information on their anticipated comfort ver- sus their experienced comfort was also requested. 200 Findings Data were treated in two distinct phases. The dependent measures were first graphed over time for fabric and design. The second phase was devoted to inferential statistics. Examination of the graphs of the dependent measures over time demonstrated a consistent trend. Subjects wearing fabrics 2 and 3 showed similar temperature data and perceptual responses over time. Besides exhibiting similar temperature, a number of the plots showed an over-all decreasing trend over time for these two fabrics, indicating that convective and/or evaporative cooling was taking place. In con- trast to this pattern, subjects wearing fabric 1 were found to have higher temperature readings. These subjects also perceived themselves to be hotter and in greater discomfort than subjects wearing fabrics 2 and 3. Thus fabric 2, the three-layer laminate fabric which had previously been shown to be an effective barrier to pesticide spray, was found to offer a similar level of thermal comfort as fabric 3, the 100% woven cotton chambray. Fabric 3 was selected for inclusion in this study, not because of its protective qualities, but rather due to its comfort characteristics. Fabric 3 is frequently now worn by the grower for pesticide application. Therefore, fabric 2 elicited similar thermal comfort responses (assessed by both physiological and perceptual measures) as fabric 3 did, yet this three-layer laminate offered significantly better protection against pesticide penetration than fabric 3. 201 Examination of the same data for design did not yield any evidence of a clear trend. There was a tendency, however, for the ventsuit design to be more thermally burdensome than the other two designs. Clothing that is worn while performing activities adds to the metabolic costs for the body, the percentage dependent on various factors including clothing weight, number of layers, and thickness (Fourt & Hollies, 1970). The ventsuit design featured an additional inner fabric layer (a 100% cotton mesh) in the back torso region. During the experiment, this mesh panel became saturated with sweat, providing both thermal advantages and disadvantages. As illustrated in Figure 57, as the panel became wetted out with sweat, the skin surface was brought closer to the fabric surface and therefore had less resistance to evaporation. This condition offered an advantage for increased cooling. Yet, clothing wet with sweat has disadvandates also, for example, clinging to the body and to other clothing. This, as noted previously, places greater burden on motion, a drag effect. -',0uter garment Air Film _._,:I‘, -_- ' “ “_ .-:~¢i.pMesh panel //////1 s...I/”////////) Figure 57.--Diagram of moist panel clinging to skin. 202 There are still other factors that likely impacted on per— ceived thermal comfort and sensation, namely the extent of specific contact area and the transient contact effects. As indicated in Figure 57, the contact area increased with sweating as the panel tended to cling to the undershirt and back. Subjects consistently rated their sensation of thermal comfort as dissatisfied or uncom- fortable. Last, the multiple layers could also have contributed to the thermal burden. Mean rectal temperature, mean weighted skin temperature (time = 90 minutes), and mean thermal sensation votes (sixth ballot) were treated as a set of conceptually related dependent measures that rep- resented different facets of a single response. As such, multivariate statistical techniques were used to test the hypotheses identified in Chapter I. The advantage of multivariate models was that with con- ceptually related measures that are intercorrelated or have different variances, the statistical analysis was not invalidated. The MANOVA results indicated that mean differences in the dependent measures for fabric were significant at the .0001 level. Mean weighted skin tem- perature strongly contributed to this statistically significant finding. There were no significant differences detected for design at the .05 level. Confidence intervals indicated that the three dependent meas— ures for fabric 1 were significantly different from those measures for fabric 3. Thermal sensation votes, which were clustered at the upper end of the nine-point scale, were not included in the MANOVA analysis. Results of the chi—square analysis showed that the null hypothesis of 203 independence for fabric was rejected at the .05 level. However, the null hypothesis for design was not rejected. Although measurement errorwasa problem for determination of percent of evaporated sweat, a clear trend was apparent. Subjects wearing fabric 2 (three-layer laminate structure) exhibited the high- est percentage of evaporated sweat, and those in fabric 1 (spun- bonded olefin fabric) the lowest percentage. Investigation of the moisture adsorbed or absorbed by the test clothing indicated that the greatest increase in weight was associated with fabric 1 and the least with fabric 2. The data indicated that evaporation was taking place for fabric 2, the fabric that showed similar physiological and perceptual data as fabric 3, the 100% cotton chambray. Anticipated comfort and willingness to wear protective clothing were analyzed using chi-square analyses by fabric and design. Infor- mation on these two variables was obtained even though the ability to generalize from the data was limited. The null hypothesis of inde- pendence for anticipated comfort and fabric was rejected at the .05 level. The data suggested that the majority of students who had found their test clothing gpplgp_than they expected were wearing fabric 2, and 7 % of those who rated the clothing ygpmp:_than they anticipated were wearing fabric 1. The null hypothesis of independence for this variable and design could not be rejected at the .05 level. The data for willingness to wear protective clothing did not suggest any meaningful pattern for either design or fabric. Neither null hypothesis of independence could be rejected. The majority of 204 the subjects were willing to wear the clothing either voluntarily or if required to do so. Thus, both phases of the data treatment yielded a consistent, unmistakable pattern for fabric, but not design. These analyses confirmed that one protective fabric, the three-layer laminate (fabric 2), offered similar thermal-comfort levels as the 100% cotton chambray (fabric 3). The coverall design appeared to be as comfortable as the two-piece jeans and shirt. There was a slight trend for the ventsuit ~ 51...:44, coverall to offer less thermal comfort than the other two designs. Limitations of the Study 1. This study was limited to male college students, aged 18 to 25, at Kansas State University, in the spring of 1980. It was felt that the physiological measures, and to a lesser extent the per- ceptual measures, would likely be somewhat invariant across different male populations at similar levels of physical fitness. The conclu— sions for the two summary measures should be restricted to the popu— lation under study. 2. Students were recruited through newspaper advertisements and were paid $20 for their participation. This "encouragement" to participate and the method of acquiring a sample could have influ- enced their responses to the perceptual and summary measures. 3. The study was conducted in an environmentally controlled laboratory that was maintained at a temperature/humidity level to simulate Michigan summers. Yet, air movement was only that of still air. In the natural environment, the myriad combinations of —7 ' W ' m. l 205 temperature, humidity, air movement, and presence of trees, etc., could significantly impact on man's thermal response. Because of the air-movement specification, the test condition was probably more thermally burdensome than 85°F, 60% r.h. would be under normal con— ditions. 4. Methods used for gathering evaporated—sweat data were not sufficiently precise to tap this variable as desired. A standard towel—drying procedure would have to be carefully planned, rigidly carried out with no exceptions, and the towel would need to be placed in a plastic bag to minimize evaporation for immediate weighing. Some 1 provision would need to be made for the problem of run—off. Sugges- tions by Fourt and Hollies (1970) would be impractical to implement. 5. This study evaluated and compared the thermal response of subjects wearing selected fabrics. The results cannot be general- ized to other nonwoven and laminate fabrics. The designs tested should not be considered inclusive for what is possible for protec- tive clothing. 6. Two different chambray fabrics were used in this study. Purchased chambray yard goods were used to construct the two coverall designs, and ready-to-wear chambray shirts were purchased for the two- piece design variations. Implications The findings of this study had immediate implications for the ultimate objective of the over—all research project--that is, the development of protective apparel for pesticide users that offered 206 acceptable thermal—comfort levels. Henry's work (1980) indicated that the likelihood of eventual adoption of protective clothing by the independent growers would be enhanced if the protective garment's appearance was similar to their present work clothing. Thus, no serious consideration was given to designing garments requiring a power source for cooling. It was felt that the growers would find such clothing incompatible with their work activities and their values. Emphasis, rather, was directed toward finding a suitable fabric and an effective design that offered increased dermal protection from pesticides and a similar level of thermal comfort as commonly worn work clothing. The findings of this study offered encouragement that the ultimate goal was feasible. However, only a limited number of fabrics and designs could be evaluated in this study. Using human subjects in a climatically controlled chamber was an expensive mode of studying thermal response. And while the literature frequently recommended human-subject testing to fully evaluate thermal response to garments and climatological conditions, nevertheless a less costly means of assessing the poten- tial thermal comfort of fabrics and designs yet to be developed would be very beneficial to the over-all research effort. There are also methodological implications from this study. Measurement error was a problem with the determination of percentage of sweat that evaporated. Refinement of techniques t0'tap this vital variable is needed. The data suggest that if it is not feasible to monitor all of the dependent variables used in this study, mean skin temperature is a good predictor of thermal comfort. Also, the vwr vivt 207 nine-point thermal—sensation ballot needs further refinement. The deficiency of the scale was apparent in this heat-stress situation where many votes were clustered at the upper end of the scale. In addition, the conduct of the thermal-analysis study and the review of the thermal-comfort literature resulted in the genera- tion of design specifications. This enabled meeting objective 4. These specifications are in support of the total over—all project objective to develop functionally designed work clothing that is protective for pesticide application, while being thermally and j socially acceptable. Therefore, several of the design specifications enumerated below were derived from previous components of the total project. They are listed here to permit a complete listing of the thermal design specifications. Design Specifications The following design specifications were generated from re— vious components of the over-all research project: 1. The garment should be perceived by the users as providing thermal comfort. 2. The design should be capable of being worn over other clothing. 3. The garment should be such that users will be willing to wear the protective garments for a range of environmental conditions. The following specifications for design and for fabric were generated as an outcome of the review of the thermal—comfort ljtgrg: ture and the findings of the thermal-analysis study: 208 4. The garment design should promote evaporative and convec- tive cooling through the use of any of the following: - fabric combinations — wide openings at the neckline, sleeve, and pants edges — vents or air holes in areas of low deposition - means for increasing air flow within garment sections 5. The design should promote conductive cooling, particularly in the upper torso areas. 6. The design should be capable of being adjusted to promote thermal comfort for a range of environmental conditions. 7. The design should promote thermal comfort when the grower isn't spraying by being easily adjustable with a gloved hand. 8. The design should promote air exchange between the environ- ment and the body. 9. The fit and design of the garment should minimize physi- cal contact between the skin and the garment, particularly in the upper torso area. 10. The garment should provide a similar level of thermal comfort as that shown for denim jeans and a long-sleeved chambray shirt. (Level of comfort-—as assessed by weighted skin temperature, rectal temperature, percentage of evaporated sweat, and perceived comfort.) 11. The fabric should promote evaporative cooling by allowing body perspiration to be dissipated through the garment to the environ- ment, at a level equivalent to denim jeans and a long—sleeved shirt. 12. The fabric should promote convective cooling of the body. 13. The color of the fabric should be specified so as to minimize heat gain from the environment by radiation. 209 But the implications of the study also go beyond the over- all research project, whose scope was depicted in Figure 4 (Chapter I). The findings strongly suggest that fabric 2 offers both protection and thermal comfort. However, fabric 2 is an expensive reusable fabric that, if finally adopted for this end-use, would be repeatedly used. Thus, there are implications for the issue of laundry and decontamination. Stepping into this arena demands consideration of additional implications pertaining to the possible secondary exposure of family members to pesticides. These implications will be briefly considered. ‘ Laundering and Decontamination Referring back to the flow chart given in Figure 4 to opera- tionalize the design process, we notice that the implications of this study suggest that an essential "new” piece of the problem must be included. Before recommendations could be made advocating use of fabric 2, considerable effort is needed to examine the critical issue of decontamination. The limited research done in this area has shown inconsistent results, and none of the studies has examined pesticide removal from the specific fabric used for the thermal-analysis study. Percentage removal of pesticide has varied, and some residues have been shown to be biologically active (Easley, Laughlin, Gold, & Tupy, 1981). Southwick, Mecham, Cannon, and Gortatowski (1974) reported a dramatic example of a 70-year—old male who was admitted to a hospital for pesticide poisoning after spraying parathion on his backyard garden and fruit trees. Following the hospitalization, the 210 man showed improvement until he put on the laundered bib overalls which he had worn previously while spraying. He immediately became ill with flu-like symptoms and died the following day. Laboratory analysis of the bib overalls showed a large residue of parathion remaining, despite the laundering. Familial Exposure Recognition of occupational exposure to harmful chemicals has recently grown. But recognition that this exposure can affect not only the worker, but also his/her family, is a relatively new concept. Bellin (1981) presented data for familial exposure to beryllium and asbestos. Almost every case of household contamination presented by Bellin cited the laundering of clothing and/or linens as the contaminant source. Hardy (cited in Bellin, 1981) noted that 40 out of 60 neighborhood cases of berylliosis were due to beryllium dust which contaminated clothing, skin, shoes, car, and furniture. Consequently, since 1960, beryllium workers in this plant have been reguired to change their clothing and to shower before leaving work. The soiled clothing is sent to a commercial laundry facility. The effectiveness of these measures remains to be documented. Thus, if the health and safety of the agricultural worker is to be enhanced through the adoption of protective clothing, concern must also be focused on the implications of the use and care of this clothing for the worker's family. Those making recommendations on the frequency of laundering and the methods for laundering and storage must be cognizant of the real danger of the secondary exposure of the .r 211 worker's family. There is a need to know what is currently being done by the growers and their families. There is a need to consider attitudes and values that motivate the families regarding this issue. And there is a need for creative problem solving for the serious prob- lem of pesticide transference during laundering. Recommendations for Future Research 1. It is recommended that further work be directed toward the development and refinement of laboratory test methods to assess air, heat, and moisture transport properties that would correlate well with known human-subject data on thermal response. If laboratory test methods on the test fabrics and designs used in this study could be shown to correlate with the thermal-response data obtained with human subjects, this would facilitate the development of predictive models to assess thermal response of new fabrics and designs without human subjects. 2. It is recommended that further work be directed toward refinement of a thermal—sensation scale. Such clustering at one end of the scale diminishes the discriminating function of the instrument. 3. It is recommended that an investigation be conducted to examine the influence of age and sex on thermal response of subjects wearing protective clothing. This study might be conducted in an environmentally controlled chamber or in the field. A chamber study offers the advantage of permitting assessment of physiological vari- ables of interest as well as control of environmental variables at prescribed levels. The perceptual data on thermal comfort from a v— 212 field test, however, would offer an interesting comparison with these measures from a controlled chamber study. If the population for the field test consisted of growers, then their perceptual responses would be even more valuable to the designer. 4. It is recommended that a study be undertaken to deter- mine the efficiency of laundering and/or other decontamination pro- cedures to remove pesticide from contaminated clothing. Also, the question of whether the remaining pesticide residue is biologically active should be addressed. 5. It is recommended that current laundry and storage prac- tices of growers' families be investigated. Data on where the work clothing is stored, length of time stored, where the clothing is laundered, with what other clothing, with what kind of equipment and methods, by whom, and how frequently should be gathered in order to assess the potential for secondary familial exposure. 6. It is recommended that attitudes and the perceived risk of handling pesticides or pesticide-contaminated clothing be investi- gated for families who have a member involved in handling pesticides. It is thought that the grower who perceives himself to be at risk while spraying pesticides will be more likely to adopt protective clothing. Similarly, the family members responsible for the laundry will likely be more willing to follow recommended decontamination pro- cedures of the work clothing if a risk is perceived. 7. It is recommended that future studies consider using multivariate statistical techniques when investigating a phenomenon 213 requiring a set of dependent measures that are conceptually meaning- ful for adequate assessment. 8. It is recommended that an ecological approach be used for experimental studies when appropriate. APPENDICES 214 APPENDIX A FORMS USED IN THE PROCEDURE FOLLOWED FOR OBTAINING SUBJECTS 215 APPENDIX A] ORIENTATION STATEMENT The purpose of the study in which you are participating is to determine how man responds to his thermal environment. At the outset, you should be fully aware that the conditions to which you will be exposed may entail some physical risks including physical discomfort and mental stress. Second, you have volunteered to act as a subject and are participating on your own volition. Third, you may leave the experiment anytime you wish. Fourth, your identity as a subject will not be disclosed and anonymity will be maintained. Your participation will include completing a physical examina- tion, eating a standardized meal at the K-State Union, experiencing one-half hour of preconditioning and a two-hour environmental test exposure. During the test exposure you will be performing the physical task of walking up and down steps. You may not leave the room during the test without forfeiting your participation in this experiment. At certain intervals you will be asked to complete ballots evaluating the temperature of the environment and your comfort. You will also be wear- ing skin temperature sensors to measure your skin temperature. Your rectal temperature and heart beat will be monitored throughout the study. A registered nurse will monitor your vital signs. Any change that sug- gests danger to your physical well being will cause you to be removed from the test. For your participation you will receive $20.00 remit- tance. Do you have any questions? 216 APPENDIX A2 MEDICAL HISTORY QUESTIONNAIRE 1. Last Name, First Name, Middle Name 2. Social Security No. 3. Home Address 4. Home Phone 5. School Address 6. School Phone 7. Date 8. 1.0. No. 9. Birth TOT—A§E_______' Citizen of Ancestral Background Have you ever (please check each item) yes no lived with anyone who had TB (tuberculosis) coughed up blood bled excessively after injury or tooth extraction attempted suicide been a sleep walker Immunizations (please check) Yes No Date (Month and year are sufficient) Tetanus Diphtheria Smallpox Measles Mumps BCG Influenza Typhoid fever Polio 217 218 Do you (please check) yes no wear glasses or contact lenses have vision in both eyes wear a hearing aid stutter or stammer habitually wear a brace or support Do you smoke? yes no How many cigarettes do you smoke per day? How long have you smoked? Do you take drugs regularly? yes no Name of drug(s) and how often? (Please include any over—the-counter drugs as well as marijuana, etc.) Do you take any of the following medications? Medication e.g. yes Cantil Prednisone Blood-pressure medication Cardiac medication Ulcer medication Thyroid medication Antibiotics (except thoseprescribed forcosmetiCInedication) Dilantin Allergy injections 7““ 219 Has any relative (parent, sibling, or grandparent) had any of the below? yes no relationship Tuberculosis Heart disease Chronic kidney disease Cancer Thyroid disease (goiter) Diabetes Epilepsy Asthma Hay fever Mental disorder Abnormal bleeding Arthritis High blood pressure Migraine headaches Have you ever had or now have (Please check) yes no yes no VD ( onorrhea, syphilis, Scarlet fever etc.g Rheumatic fever Typhoid fever Hepatitis Kgdfleynztones or blood Pol iomyelitis Sugar or albumin in urine Infectious mononucleosis Nephritis or nephrosis Recurrent painful & Bed wetting since age draining ear of 12 u " Fr ue t or ainful Recurrent strep throat urifiation P Pneumonia Diabetes Urinary tract infection Heart trouble 220 Have you ever had or now have (Please check) yes no Hearing loss Chronic or frequent colds Severe tooth or gum trouble (2 wks) Head injury Skin diseases Thyroid trouble Tumor, growth, cyst or cancer Rupture or hernia Piles or rectal trouble Adverse reaction to serum, drugs or medicine Car, air, train, or sea sickness Neuritis Paralysis Epilepsy Convulsions or seizures Frequent trouble sleeping Depression Excessive worry Loss of memory, amnesia Nervous trouble of any kind Periods of unconsciousness, fainting Measles (regular, hard, red) Measles (German, 3—day) Mumps Chicken pox Diphtheria Whooping cough List continues on next page. Please fill out in the same manner. Thank you! 221 yes no High or low blood pressure Palpitations or pounding heart Pain or pressure in chest Shortness of breath Chronic cough Asthma Hay fever Sinusitis Frequent indigestion Stomach, liver or intestinal trouble Gallbladder trouble or gallstones Jaundice Ulcer Swollen or painful joints Cramps in your legs Broken bones Arthritis, rheumatism or bursitis Bone or joint deformity Lameness Loss of finger, toe or extremity Painful or "trick” elbow or shoulder Foot trouble Anemia Frequent headaches Dizziness or fainting spells Eye trouble Ear, nose or throat trouble Comments: (Do not write in this space) I certify that the above information is true and correct to the best of my knowledge. Signature Date 222 Please do not write on this page! TO BE COMPLETED BY NURSE Name Date Test Date Wt. Ht. TPR Sex (Male) (Female) Blood Pressure 7 Pulse Heart Sounds EKG Strip: Rhythm Comments: Urinalysis: Sp. Gr. pH Protein Glucose Ketones Bilirubin Occult Blood Urobilinogen Blood Test: Hb Hct SMA 12 results attached___ Skin Fold: Tri Eye Color Pect College yr. ABD ILL Years at present job % Fat TBF c.v. Fitness LBM Race lst Load KPM Min(S) Hr 2nd Load KPM Min(S) Hr 3rd Load KPM Min(S) Hr 4th Load KPM Min(S) Hr Dominant Grip Strength Trunk Flex Inches 00 you exercise regularly? Yes No If so, what and how Physical Exam Form often? APPENDIX A3 Your test will be INSTRUCTIONS Unless notifying the nurse, take no drugs, medication or alco- holic beverages 12 hours before the test. 00 not eat or drink anything except water after 11 p.m. the evening before your test. Be sure to bathe or shower before reporting for the test. Wear tennis shoes and socks the day of your test. Report to the student union at ___ a.m. for breakfast. Tell the cafeteria per- sonnel that you are a test subject and they will give you the high protein breakfast free. You must eat all of this and drink a glass of water. Do not add or substitute to this meal. Immediately after eating breakfast report to the pre—test room of the Institute for Environmental Research. If the outside door is locked please wait on the benches outside E 63 until we unlock the door. Unless you notify us by 3 p.m. on the day ppfgyp_your test is scheduled, it will be assumed that you will keep this appointment. If you do not or do not meet this appointment, you will ppt_be scheduled at a later date. The tests are too expensive to run with less than the required six subjects who are scheduled. Any questions please call IER 532-5620. APPENDIX A 4 BREAKFAST INSTRUCTIONS You should receive from the grill scrambled eggs, breakfast patty, and dry toast. You will get a small glass of white skim milk and a small glass of juice (orange or grape for yourself). You may have all the water you wish but pp_other liquids. You may have pp_butter, jelly, salt, pepper, mustard, catsup, or seasoning of any type. 224 APPENDIX B FORMS USED DURING THE CONDUCT OF THE EXPERIMENT 225 Subject Name APPENDIX B l Garment # 1. Subject Weight Pre—Test 2. Subject Weight Post-Test 226 Subject # Test # Clothing Wt. Pre-Test Clothing Wt. Post—Test Thermos Wt. Pre—Test Thermos Wt. Post-Test _p _ ,, , swag: APPENDIX B2 AGREEMENT AND RELEASE 1. I, , volunteer to par- ticipate in a project in connection with research studies to be con- ducted by Kansas State University. 2. I realize that participation may impose physical and/or mental stresses upon me and/or the other subjects. I believe that I am physically and mentally fit to withstand any such stresses. 3. I understand that I will be observed during my participation and that my conduct and/or voice may be recorded by photographic and/or recording devices. I may have attached to my person sensors to measure temperature, pulse, blood pressure, etc. I also realize that public reports and articles may be made of the experiments and all of the observations and I consent to publication of such, including the use of photographs. 4. I hereby authorize the Kansas State University to remove me from the evaluation exercise at any time and for any reason. I agree to leave said exercise willingly when asked to do so. 5. I understand that I will be permitted to leave the evalua- tion exercise at any time that I find that I am unable to withstand the conditions and request to be relieved. 6. As compensation for my voluntary services as a participant in the aforesaid studies, Kansas State University will pay me. It is clearly understood and agreed, however, that in no event am I to be considered an employee of Kansas State University during such partici- pation. Therefore, no Social Security, income tax, retirement, or other benefits of employment will be deducted or accrue. 7. I hereby agree, under penalty of forfeiture of all compensa- tion due me, not to give information regarding these studies to any public news media nor to publicize any articles or other accounts thereof without prior written approval by Kansas State University. I have signed the herein Agreement and Release, this day of , 19 . Signature 227 APPENDIX B3 Subject Name and No. Test No. Thermister No. Chest Arm Leg Rectal 228 APPENDIX B4 HEALTH QUESTIONNAIRE Subject Name and No. Test No. Have you consumed alcohol within 12 hours? Yes No If yes, what? How much? How long ago? Have you taken any drugs within 12 hours? Yes No If yes, what? How much? How long ago? How many hours sleep did you have last night? 229 APPENDIX 85 SUMMARY QUESTIONS Name and Subject No. Test No. Please answer the following questions by checking the appropriate blank. 1. I found the clothing that I wore for the study to be . . . cooler warmer about the same . as I expected. 2. The test you have just completed was conducted to measure thermal comfort of protective garments at 85°F. Knowing that this clothing would provide protection against harmful chemicals in your work, indicate your willingness to wear this garment: I would be willing to wear it under these temperature conditions. I would wear it if the temperature was less than 85°F. I would wear it only if required to do so. I would not wear it. 230 APPENDIX B6 POST-TEST INFORMATION SHEET The primary effect of your heat exposure is a loss of fluid and of salt; therefore, you may experience some transient light- headedness, headaches, nausea, or muscle cramps. You should treat these temporary problems by rest, fluid, and salt intake. Example: Gatorade, sodas, and salted popcorn, potato chips, etc. If any symptoms are severe or persist despite fluid and salt intake, call Environmental Research nurse at 532-5620 or your own family physician. 231 APPENDIX B7 KANSAS STATE UNIVERSITY Manhattan, Kansas Receipt Form for Cash Payments to Research Subjects Fund Name Institute for Environ. Res. Account Name Mich. State Univ. Study K.S.U. Account No. 52442—2757 P.P.O. No. I certify that I have served as a subject for the research project entitled Thermal component of Reduction of Dermal Exposure of the Operator in Pesticide Appiication and that I have received'the amount set opposite my name f0r this service. NAME (lst line) & SOC. SEC. COMPLETE ADDRESS NUMBER SIGNATURE DATE AMOUNT 232 APPENDIX C EXAMINATION OF TEMPERATURE DATA 233 Mean Rectal Temperature APPENDIX C1 SAMPLE MINI-TAB COMPUTER GRAPH OF TEMPERATURE DATA FOR DESIGN 3 C11 100 50+ 100 35+ 100 20+ — B 100 05+ - B - B - 2 99.90+ 2 A A 2 A - A — B 99 75+ C C - C C - C C C A 3 2 99 60+ C C - 2 A - C C B 99 45+ A - C A B 99 30+ 2 B - 2 — a . _ - c Fabric 1 - B 99 15+ A B . - Fabr1c 2 = A j 3 3 Fabric 3 = C 99.00+ B 9B.BS+ 3.0 6.0 9.0 12.0 15.0 16.0 21 Time 234 "‘s_zd! 13 13 ROOM CHEST AKM LEG RECTAL RECTAL 15 15 R00” CHEST ARM LE6 RECTAL LEO RECTAL 17 17 ROOM CHEST ARM LLG RECTAL APPENDIX C 2 SAMPLE COMPUTER PRINTOUT OF LISTING OF SUBJECTS' TEMPERATURE DATA 11 0479 06 at 4A 155.4156o3 0564.0 05r252 1380.5 1380.5 d1 527326926456t75475557645764!7645753E76457545854575467446654686548645844513 8436 8471 6559 5:52 5507 9519 9392 9559 4466 9525 9361 9501 9269 9253 9251 9326 9934 9932 9926 9928 (550 9955 9463 9232 9921 11 0512 07 01 5? 197.0197. bl 51912991764683388919911 8461 8511 6526 8592 9413 9476 9501 9582 9546 a626 9617 9648 “073 9148 9025 9115 9707 9653 9648 9692 8605 9513 9613 9007 9728 d513 6501 6505 5484 B452 6496 6466 0490 8486 8484 5298 9?Er 9265 9G3; 9538 9366 9513 9394 9346 9361 9928 9919 9321 9496 9407 9294 9457 9376 9261 9315 9546 9492 9303 9446 9436 9260 “346 9366 93~h 9357 9405 9396 9353 9928 9926 9917 9°32 9926 9926 9936 0 0515.6 0766.7 1450.7 0914.9 9891°9119691991199919911998189119991991199919911922 6607 9630 8571 8500 9503 9367 6471 B417 B405 8421 8386 8463 8613 I41605 9601 9507 9609 9573 9409 9603 9671 9575 9478 9632 9607 9542 9611 961349515 9655 9221 9175 9119 9301 9403 SIHR 9298 9411 9248 9353 64 94 94 54 94 £6 95 95 91 976) 9767 9775 9600 9946 9944 9961 9973 9969 9964 97 Il 0522 09 06 BB 154.5154.5 1151-1 1361.9 1377.1 0596.3 BI 53722773754546569919711899298119991981199919911999199119991991199919911932 8461 6511 6526 8592 9363 9436 9455 9523 9415 9423 9469 9521 9421 9428 9423 9350 9919 9921 9919 9903 8605 a530 9540 9396 9892 6607 8571 8500 8471 8417 8405 6421 6386 8463 8613 9646 952] 9573 9642 9636 9592 9667 9632 9615 9707 9559 9592 9409 9425 9578 9488 9475 9507 9446 9440 956“ 9523 9386 9546 9469 9375 9561 9571 9436 9548 9928 9932 9926 9953 9940 9936 9967 9959 9946 9963 99 II 0522 05 11 3A 150.5151.8 0721.9 0750.7 1557.2 0491.5 61 537347738737542697287228991“7218991932129819621799195438992943279919542733 9461 6511 8526 8592 9559 9619 9623 9615 9407 9515 9536 9569 9159 9205 9198 9196 9945 9938 993K 9932 B605 9555 @525 9246 9928 8607 6571 8500 8471 8417 8405 0421 8366 B463 6613 9640 5553 9528 9619 957d 9511 9566 9532 9476 9596 94?? 9438 9536 9501 9442 9415 9513 9436 9396 9521 9476 9923 9421 9400 9919 9921 9511 9434 9356 9496 9419 9354 9540 9936 9923 9934 9975 9963 9967 9990 11 0522 07 16 4B 172.5175.5 0572.9 0633.2 1387.6 0674.3 61 42821981663674367737733777377337783783387828825778278226662882258929822933 6461 6511 6526 8592 9521 9505 9507 9484 9470 9338 93MH 9459 9234 9182 9155 9136 3575 9876 9876 9871 8605 9459 9430 9230 4867 86L7 9492 94(5 9446 $87! 8571 8500 9515 9432 9351 9432 6417 9359 9662 9586 235 H47] 8417 $405 6421 8386 6463 0613 9494 9364 9376 9469 9417 9444 9519 9407 9294 9376 9361 9290 9369 9359 9515 9453 9340 9463 9386 9346 9476 9692 9900 9903 9907 9919 9911 9909 86 96 95 95 86 94 91 93 99 BIBLIOGRAPHY 236 BIBLIOGRAPHY Alexander, C. 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