Validity of Thermal Comfort Indices Based on Human Physiological Responses in Typical Open Pit Mines

Abstract

Working in hot environments is one of the common hazards in the workplaces, which can cause heat-related illnesses, affect workers’ health and increase a risk of occupational injuries and accidents. The aim of this study was to assess and compare thermal comfort indices of humidex, Discomfort Index (DI), and ET with physiological responses in the open-pit mines in Tehran Province, Iran. This cross-sectional study was conducted in summer 2016 on 175 male workers in 12 construction materials mines in Tehran Province, Iran. Environmental and physiological parameters were measured simultaneously at three periods and thermal indices were determined as well. In this study, correlation coefficients of indices at different times of day were analyzed. Data were analyzed using SPSS 18 software and Pearson correlation. There was high correlation between thermal comfort indices with each other. All three indices used in this study had an appropriate relationship with core body temperature. Oral temperature had a greater correlation coefficient with thermal indices compared to the tympanic membrane temperature and skin temperature. Humidex had a high correlation coefficient with environmental parameters and physiological responses. The Humidex index is more valid than ET and DI indices. Humidex, among the studied indices, despite being simple, lack of need for sophisticated equipment to measure, low cost and easy interpretation can be used in open-pit mining.

Keywords

• Heat stress
• Thermal indices
• Physiological parameters
• Open-pit mines.