Total Evaporative Resistance for Different Clothing Ensembles at Three Levels of Metabolic Demands

Details

• Personal Author:
  Ashley C ; Bernard T ; Caravello V ; McCullough E
• Description:
  With regard to heat stress, the limiting factor inherent in clothing ensembles is the total evaporative resistance. For the same work demands, the greater the evaporative resistance of the clothing, the lesser the ability to cool by sweat evaporation and hence the lower the environmental contributors to heat stress, especially water vapor pressure, must be. Knowing the evaporative resistance provides a means to compare candidate ensembles. Further, a value for evaporative resistance means that a rational method, such as the ISO Required Sweat Rate, can be used to assess the heat stress exposure. In this study, the evaporative resistance of five clothing ensembles (cotton work clothes, cotton coveralls, Tyvek 1424, NexGen, and Tychem) was determined empirically from wear tests. The ensembles were configured similarly in that there were no hoods. The humidity was held constant at 50% rh, and three levels of metabolic rate (80, 160,240 W/m2) were explored. Fifteen heat-acclimated participants (11 men and 4 women) completed trials for all combinations of clothing ensemble and environment. A three-way ANOVA (ensemble, metabolic rate, participants) was used to analyze the data. Significant differences (p<0.0001) among ensembles, metabolic rates, participants, and the interaction between ensembles and metabolic rate was found. As expected, Tychem had the highest resistance at 0.034 kPa m2/W. NexGen was next at 0.02.7; followed by Tyvek 1424 at 0.026. Coveralls was 0.025, and work clothes was 0.024. Pairwise comparisons adjusted for multiple comparisons were used to locate the differences among ensembles. Tychem was different from all others and NexGen was different from work clothes. We also found that evaporative resistance decreased with increased metabolic rate. This can be explained by the pumping action associated with increased work. [Description provided by NIOSH]
• Subjects:
  Heat Stress Disorders Hot Temperature Occupational Health Safety Temperature
• Keywords:
  Clothing Fabrics Heat Exposure Heat Stress Metabolic Rate Temperature Effects
• Publisher:
  American Industrial Hygiene Association
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Abstract or Summary
• Place as Subject:
  Florida ; Kansas ; OSHA Region 4 ; OSHA Region 7
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  41
• NIOSHTIC Number:
  nn:20057941
• Citation:
  American Industrial Hygiene Conference and Exposition, May 8-13, 2004, Atlanta, Georgia. Fairfax, VA: American Industrial Hygiene Association, 2004 May; :41
• Federal Fiscal Year:
  2004
• Performing Organization:
  University of South Florida, Tampa, Florida
• Peer Reviewed:
  False
• Start Date:
  20000930
• Source Full Name:
  American Industrial Hygiene Conference and Exposition, May 8-13, 2004, Atlanta, Georgia
• End Date:
  20040929
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:f727045f673a94c67d848c4d5e7586f110001c47e442512a5d790e1504fd65f306b2c3afb6c03edab040e80a66a1d980285e483670abbb0e15986dab6a7fd60b
• Download URL:
  https://stacks.cdc.gov/view/cdc/215143/cdc_215143_DS1.pdf
• File Type:
  [PDF - 280.87 KB ]