Comparison of heat stress action levels.
NIOSH 1980 Dec; :21-31
Proposed action levels for continuous and intermittent work in heat were reviewed and compared and the possible use of the same index to determine the action levels in hot dry conditions and hot humid conditions was examined. The wet bulb globe temperature index, which is used to evaluate the level of heat stress in industrial exposure, was found to be convenient and easy to use, but it was not well suited to calculate the heat loads required for engineering controls. The recommended wet bulb globe temperature action levels for various degrees of physical activity during continuous work in heat were found to be about the same in all studies based on this particular method. On the contrary, contradictory and confused data were obtained in intermittent work in heat where the values of the wet bulb globe temperature index in the rest and work areas vary. Based on his own research, the author concludes that the wet bulb globe temperature is not the best index for the evaluation of thermal stress in hot humid climates and recommends the use of the corrected temperature index or the globe temperature index in situations of this nature. Furthermore, the author suggests that the use of the two indices (one for low and one for hot humidity conditions) may be necessary to estimate the degree of stress for a given hot environment.
Thermal-effects; Occupational-health; Occupational-exposure; Industrial-environment; Industrial-hygiene; Wet-bulb-thermometers; Heat-stress
DHHS (NIOSH) Publication No. 81-108
Proceedings of a NIOSH Workshop on Recommended Heat Stress Standards, September 17-19, 1979, Cincinnati, Ohio