Evaluation and Validation of Heat Stress Indices in Iranian Oil Terminals

Most of Iranian Oil Terminals are located in tropical regions and consequently, disorders of heat stress among workers are expected. There are many heat stress indices with self-advantages and disadvantages which are used for evaluating the amount of heat stress. The aim of the present study was to evaluate the reliability of WBGT, ET and CET indices by comparison to core body temperature in Kharg Oil Terminal Company. Participants (n=94) were workers in different units of the terminal. After identifying units and type of activities, the air and wet temperatures, WBGT, and core body temperature (oral and ear drum) in three situations including outdoor and indoor activities were measured. The means and standard deviations of WBGT, ET, and CET in the indoor and outdoor workplaces were 26.9±4.29, 25.94±4.05, 26.11±3.6 °C and 29.76±3.51, 28.03±4.05, 29.36±3.51 °C, respectively. The statistical correlation between the above mentioned heat stress indices with oral and tympanic temperatures were significant (p < 0.001). The regression equations showed that the most determinant coefficient belongs to WBGT and oral temperature. It was concluded that the WBGT, ET, and CET with core body temperature had significant correlations and that WBGT was the most accurate index to determine the heat stress among workers.