Apparent Evaporative Resistance at Critical Conditions for Five Clothing Ensembles

Details

• Personal Author:
  Ashley CD ; Bernard, Thomas E. ; Caravello V ; McCullough EA
• Description:
  A limiting factor for clothing ensembles inherent during heat stress exposures is the evaporative resistance, which can be used to compare candidate ensembles and in rational models of heat exchange. In this study, the apparent total evaporative resistance of five clothing ensembles (cotton work clothes, cotton coveralls, and coveralls made of Tyvek 1424 and 1427, NexGen and Tychem QC was estimated empirically from wear trials using a progressive heat stress protocol and from clothing insulation adjustments based on ISO 9920 (2007) and wetness. The metabolic rate was moderate at 165 W m(-2) and relative humidity was held at 50%. Twenty-nine heat-acclimated participants (20 men and 9 women) completed trials for all clothing ensembles. A general linear mixed effects model (ensemble and participants as a random effect) was used to analyze the data. Significant differences (p < 0.0001) among ensembles were observed for apparent total evaporative resistance. As expected, Tychem QC had the highest apparent total evaporative resistance at 0.033 kPa m(2) W(-1). NexGen was next at 0.017 kPa m(2) W(-1). These were followed by Tyvek 1424 at 0.015 kPa m(2) W(-1), and Tyvek 1427, Cotton Coveralls and Work Clothes all at 0.013 kPa m(2) W(-1). This wear test method improves on past methods using the progressive protocol to determine evaporative resistance by including the effects of movement, air motion and wetness on the estimate of clothing insulation. The pattern of evaporative resistance is the same as that for critical WBGTs and a linear relationship between apparent total evaporative resistance and WBGT clothing adjustment factor is suggested. With the large sample size, a good estimate of sample variance associated with progressive method can be made, where the standard error is 0.0044 kPa m(2) W(-1) with a 95% confidence interval of 0.0040-0.0050 kPa m(2) W(-1). [Description provided by NIOSH]
• Subjects:
  Environmental Health Heat Stress Disorders Hot Temperature Humidity Occupational Health Personal Protective Equipment Protective Clothing Safety Temperature Textile Industry
• Keywords:
  Air-temperature Clothing Environmental-factors Heat Heat-exposure Heat-stress Physiological-testing Protective-clothing Statistical-analysis Temperature-control Temperature-effects Textiles

  More +
• ISSN:
  1439-6319
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Florida ; OSHA Region 4
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  361-367
• Volume:
  104
• Issue:
  2
• NIOSHTIC Number:
  nn:20034701
• Citation:
  Eur J Appl Physiol 2008 Sep; 104(2):361-367
• Contact Point Address:
  Thomas E. Bernard, University of South Florida, College of Public Health, 13201 Bruce B. Downs Blvd., Tampa, FL 33612-3805
• Email:
  tbernard@health.usf.edu
• Federal Fiscal Year:
  2008
• NORA Priority Area:
  Research Tools and Approaches: Exposure Assessment Methods
• Performing Organization:
  University of South Florida, Tampa, Florida
• Peer Reviewed:
  True
• Start Date:
  20000930
• Source Full Name:
  European Journal of Applied Physiology
• End Date:
  20040929
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:9ba0eb7f45f24cd4609be9fe2a06153f749ae882ee39a33a1253520453e0ff9d24dfea8199453b1fcb468fdeb42d9cf8cd6e38ba3c4d87af9d43ed506b375982
• Download URL:
  https://stacks.cdc.gov/view/cdc/186812/cdc_186812_DS1.pdf
• File Type:
  [PDF - 263.37 KB ]