Mining Project: Predicting Heat Strain in Metal and Nonmetal Mines

Research Summary

Many workers employed at both surface and underground mines in the United States are exposed to excessive heat, yet heat strain in U.S. mining has been inadequately studied. As mining technology permits expansion into deeper, hotter environments, the incidence of heat strain among miners is likely to increase. While it is fairly well understood that heat strain can progress to severe heat illness such as heat exhaustion or heat stroke, less well recognized is the prospect that heat strain may also lead to decreased cognitive performance, which could increase risk of injuries in a mining environment. A clear understanding of factors that predict when a miner has reached the limits of his or her ability to perform job tasks safely is a crucial step in managing heat strain in industrial settings.

Establishing methods to evaluate the cognitive effects of heat strain and identifying predictive indicators that can alert workers to an imminent decrease in mental performance would address an important gap in heat research. Although previous research among miners has provided important insights into heat-related factors such as hydration and acclimatization, most mining-related research has not attempted to evaluate mental performance under heat stress. Various predictive heat stress indices have been developed to make use of physiologic measurements such as core body temperature, but few have considered cognitive functions such as vigilance, attention, short-term memory, or higher-level executive functions such as judgment or decision making. Studies focused on U.S. miners have been largely absent and are needed to assess the most effective methods for predicting heat strain in mining, thereby enabling the development of appropriate controls.

This research will address this need by way of three research aims, as follows.

1. Determine if an increase in heat stress from environmental parameters such as temperature and humidity and the subsequent increase in heat strain (heart rate and body temperature) correlates with decreased cognitive performance.
2. Assess the extent to which personal risk factors can improve the prediction of cognitive impairment in combination with physiologic and environmental parameters.
3. Develop recommendations to improve the detection, mitigate the risk, and identify workers with increased susceptibility to heat-related cognitive impairment among miners.

This project constitutes extensive follow-on research to the one-year pilot project, “Predicting Heat Strain in Underground Metal and Nonmetal Miners,” which helped to shape the research methodology and aims. Findings from this five-year project research will increase the knowledge base of heat stress in U.S. mining, providing information on the extent to which heat stress affects cognitive performance. The study will contribute scientific evidence that the mining industry can use to develop guidelines and policies to mitigate the risk of heat strain and its complications.