Assessment and Comparison of Thermal Indices with Physiological parameters Case Study: Open-pit Mines in Tehran Province

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. Several indices have been introduced to evaluate the heat stress that each one has own limitations. The aim of this study was to assess and compare thermal indices of humidex, DI and ET with physiological indices 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 coefficient.
The findings showed that all three indices used in this study had an appropriate relationship with core body temperature. The physiological indices of oral temperature showed 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. On the other hand, among the thermal indices used in this study, Humidex had more correlationcoefficient with two other indices.
It can be concluded that humidex, among the studied indices, despite being simple, lack of need for sophisticated equipment to measure, low cost and easy interpretation can be used as substitute index in open-pit mining.