The ability of the U.S. military's WBGT-based flag system to recommend safe heat stress exposures.

Details

• Personal Author:
  Almario DR
• Description:
  The U.S. military currently uses a flag system based on wet-bulb globe temperature (WBGT) and metabolic rate to recommend heat stress exposure limits. This paper addresses the ability of the flag system to recommend safe heat exposures in a non-military population. Two progressive heat stress studies provided data on 528 observations of safe or unsafe exposures of 4 hours over a range of WBGT conditions and metabolic rates using 29 participants wearing woven cotton clothing. For the two studies, range of WBGT conditions was 25 to 42 degrees C, and the range of metabolic rates was 100 to 650 watts. These exposures were compared with the flag system's recommendations of safe exposure to determine the sensitivity and specificity of the flag system. A separate study provided 62 observations with participants undergoing a time-limited protocol at constant WBGT conditions. Observed durations of safe exposure time were compared to the flag system's recommended safe limits to determine sensitivity and specificity. Based on the progressive protocol, sensitivity and specificity of the flag system for five ranges of WBGT and three categories of metabolic rate were 0.98 and 0.25, respectively. For the time-limited protocol, which applied only to the highest range of WBGT and light and moderate metabolic rate, both sensitivity and specificity were zero. This study suggests that the flag system has high sensitivity but low specificity for long duration exposures, along with low sensitivity and specificity for time-limited exposures. However, the WBGT exposures in the time-limited trials were substantially higher than the threshold for the highest WBGT range in the flag system, which may account for the system's unexpected performance in the time-limited protocol. [Description provided by NIOSH]
• Subjects:
  Environmental Exposure Heat Stress Disorders Hot Temperature Men Occupational Health Risk Assessment Risk Factors Safety Women
• Keywords:
  Author Keywords: Sensitivity; Specificity; Occupational; Prevention Military Personnel; Metabolic Rate; Heat Stress; Exposure Levels; Exposure Limits; Risk Factors; Safety; Heat Exposure; Humans; Men; Women;
• Publisher:
  University of South Florida
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Thesis
• 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:
  1-28
• NIOSHTIC Number:
  nn:20065605
• Citation:
  Tampa, FL: University of South Florida, 2019 Mar; :1-28
• Email:
  david.almario@gmail.com
• Federal Fiscal Year:
  2019
• Performing Organization:
  Sunshine Education and Research Center, University of South Florida
• Peer Reviewed:
  False
• Start Date:
  20050701
• Source Full Name:
  The ability of the U.S. military's WBGT-based flag system to recommend safe heat stress exposures
• End Date:
  20290630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:a505f04a1635369dda65465d75deadc511fa532306ab70572e462876e55b529ab63d3154fa32aa40ed66221fcdce56f7947dc6deb7cf59d976178690d974d377
• Download URL:
  https://stacks.cdc.gov/view/cdc/249488/cdc_249488_DS1.pdf
• File Type:
  [PDF - 604.81 KB ]