Benchmarking Heat Index as an occupational exposure limit for heat stress.

While wet bulb globe temperature (WBGT) is the long-accepted index to represent the environmental contributions to heat stress, Heat Index (HI) is a commonly reported index and is used for heat stress guidance. The purpose of this article was to propose an HI-based heat stress exposure limit. The data came from previous progressive heat stress studies that identified the critical conditions between sustainable and unsustainable exposures.

Heat stress risk profiles for three non-woven coveralls.

The ACGIH® Threshold Limit Value® (TLV®) is used to limit heat stress exposures so that most workers can maintain thermal equilibrium. That is, the TLV was set to an upper limit of Sustainable exposures for most people. This article addresses the ability of the TLV to differentiate between Sustainable and Unsustainable heat exposures for four clothing ensembles over a range of environmental factors and metabolic rates (M).

Ability to Discriminate Between Sustainable and Unsustainable Heat Stress Exposures-Part 2: Physiological Indicators.

Objectives: There are times when it is not practical to assess heat stress using environmental metrics and metabolic rate, and heat strain may provide an alternative approach. Heat strain indicators have been used for decades as tools for monitoring physiological responses to work in hot environments. Common indicators of heat strain are body core temperature (assessed here as rectal temperature Tre), heart rate (HR), and average skin temperature (Tsk).

Ability to Discriminate Between Sustainable and Unsustainable Heat Stress Exposures-Part 1: WBGT Exposure Limits.

Objectives: Heat stress exposure limits based on wet-bulb globe temperature (WBGT) were designed to limit exposures to those that could be sustained for an 8-h day using limited data from Lind in the 1960s. In general, Sustainable exposures are heat stress levels at which thermal equilibrium can be achieved, and Unsustainable exposures occur when there is a steady increase in core temperature. This paper addresses the ability of the ACGIH® Threshold Limit Value (TLV®) to differentiate between Sustainable and Unsustainable heat exposures, to propose alternative occupational exposure limits, and ask whether an adjustment for body surface area improves the exposure decision.

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.