The Relationship between WBGT Index with Physiological Responses of Open-Pit Mine Workers in Hot and Dry Weather

Hot working conditions are common in open-pit mines where workers are exposed to heat stress. Investigating the hot working environments may lead to preventing diseases caused by thermal stress in mines. The aim of this study was to evaluate the relationship between WBGT thermal stress index and physiological parameters in the iron ore miners.
The present descriptive study was conducted on 120 healthy men in the summer season. Tympanic and skin temperatures were measured using a FT70 model thermometer manufactured by Beurer Co, Germany. Heart rate and blood pressure were measured using Emsig BO26 model (Taiwan) digital instrumentation. All environmental and physiological parameters were simultaneously measured and recorded. The WBGT index was calculated using the formula. Finally, the correlations were evaluated using linear regression and Pearson's correlation.
The statistically significant correlation between WBGT heat stress index and physiological parameters was found. The Pearson's correlations between WBGT index and tympanic temperature, skin temperature, heart rate, systolic and diastolic blood pressure were 0.592, 0.557, 0.624, 0.486 and 0.419, respectively.
WBGT index showed a high correlation with physiological parameters, including tympanic temperature, skin temperature, heart rate, systolic and diastolic blood pressure, and had the highest correlation with heart rate. WBGT index has an acceptable correlation with physiological parameters of Workers in open pit mines and can be a suitable index to evaluate thermal stress in such working environments.