Exertional heat illness and acute injury related to ambient wet bulb globe temperature.

BACKGROUND: The Deepwater Horizon disaster cleanup effort provided an opportunity to examine the effects of ambient thermal conditions on exertional heat illness (EHI) and acute injury (AI). METHODS: The outcomes were daily person-based frequencies of EHI and AI. Exposures were maximum estimated WBGT (WBGTmax) and severity. Previous day's cumulative effect was assessed by introducing previous day's WBGTmax into the model. RESULTS: EHI and AI were higher in workers exposed above a WBGTmax of 20°C (RR 1.40 and RR 1.06/°C, respectively). Exposures above 28°C-WBGTmax on the day of the EHI and/or the day before were associated with higher risk of EHI due to an interaction between previous day's environmental conditions and the current day (RRs from 1.0-10.4). CONCLUSIONS: The risk for EHI and AI were higher with increasing WBGTmax. There was evidence of a cumulative effect from the prior day's WBGTmax for EHI. Am. J. Ind. Med. 59:1169-1176, 2016. © 2016 Wiley Periodicals, Inc.