Heat tolerance and the validity of occupational heat exposure limits in women during moderate-intensity work

Abstract

To mitigate excessive rises in core temperature (>1◦C) in non-heat acclimatized workers, the American Conference of Governmental Industrial Hygienists (ACGIH) provides heat stress limits (Action Limit Values; ALV), defined by the wet-bulb globe temperature (WBGT) and a worker’s metabolic rate. However, since these limits are based on data from men, their suitability for women remains unclear. We therefore assessed core temperature and heart rate in men (n = 19; body surface area-to-mass ratio: 250 (SD 17) cm2 /kg) and women (n = 15; body surface area-to-mass ratio: 268 (SD 24) cm2 /kg) aged 18–45 years during 180 min of walking at a moderate metabolic rate (200 W/m2 ) in WBGTs below (16 and 24◦C) and above (28 and 32◦C) ACGIH ALV. Sex did not significantly influence (i) rises in core temperature, irrespective of WBGT, (ii) the proportion of participants with rises in core temperature >1◦C in environments below ACGIH limits, and (iii) work duration before rises in core temperature exceeded 1◦C or volitional termination in environments above ACGIH limits. Although further studies are needed, these findings indicate that for the purpose of mitigating rises in core temperature exceeding recommended limits (>1◦C), ACGIH guidelines have comparable effectiveness in non-heat acclimatized men and women during moderate-intensity work.