Comparing the Core Body Temperature and the Heat Stress indices of HSI and WBGT in lorestan Steels Industry Workers

Background & Aims of the Study: Heat Stress is a major factor in many industrials and heat stress is one of occupational hazards in the workplace and severely affects the health and productivity, heat stress can decrease efficiency, increase accidents and reduce safety levels. Aim of this study was comparing the heat stress indices of HSI and WBGT and core body temperature in steels industry workers. In this descriptive analysis study, 41 acclimatized and healthy male were participated in the study. Subjects selected by census method. Environmental climatic parameters were measured and then heat stress evaluated according to HSI index, WBGT index and core body temperature. This study was done in the hottest season in August and the hottest hours (11 to 14) at the location of the workers. All data analyzed by the SPSS version 16 and in order to establish a relationship between measured parameters and the core body temperature and the heat stress indices Poisson correlation coefficient was used. Regarding on the results, mean of WBGT index was 40.02 and mean of HSI index was 489.97. It showed that the all workers expose to high heat stress. Whilst mean of core body temperature was 37.19°c and maximum of core body temperature was 38.5°c. For estimating heat stress is better use of the biological monitoring method such as core body temperature which may have been closer to reality heat stress in exposed workers. Pearson correlation coefficient between the core body temperatures has less correlation with globe temperature (r= 0.648), relative humidity (r= 0.307) and with natural wet bulb temperature (r= 0.469) than HSI and WBGT. WBGT has high correlation with globe temperature (r= 0.956) and natural wet bulb temperature (r= 0.877) so this finding can prove that WBGT index shows higher heat stress than core body temperatures. the Pearson correlation coefficient between HSI with relative humidity is r=0.619 and HSI has more correlation with relative humidity than core body temperature (r= 0.307) and WBGT(r= 0.494) the HSI index has not statistically significant relation with air velocity (p=0.058) and HSI index have limitations for assessing heat stress in environments with high relative humidity and low air movement.