Comparing the Core Body Temperature and the Heat Stress Indices of HSI and WBGT in Lorestan Steels Industry Workers, Iran

Background & Aims of the Study: Heat Stress is a major factor in many industrials andheat stress is one of occupational hazards in the workplace and severely affects the healthand productivity, heat stress can decrease efficiency, increase accidents and reduce safetylevels. Aim of this study was comparing the heat stress indices of HSI and WBGT and corebody temperature in steels industry workers.Materials & Methods: In this descriptive analysis study, 41 acclimatized and healthy malewere participated in the study. Subjects selected by census method. Environmental climaticparameters were measured and then heat stress evaluated according to HSI index, WBGTindex and core body temperature. This study was done in the hottest season in August andthe hottest hours (11 to 14) at the location of the workers. All data analyzed by the SPSSversion 16 and in order to establish a relationship between measured parameters and thecore body temperature and the heat stress indices Poisson correlation coefficient was used.Results: Regarding on the results, mean of WBGT index was 40.02 and mean of HSI indexwas 489.97. It showed that the all workers expose to high heat stress. Whilst mean of corebody temperature was 37.19°c and maximum of core body temperature was 38.5°c.Conclusions: For estimating heat stress is better use of the biological monitoring methodsuch as core body temperature which may have been closer to reality heat stress in exposedworkers. Pearson correlation coefficient between the core body temperatures has lesscorrelation with globe temperature (r= 0.648), relative humidity (r= 0.307) and with naturalwet bulb temperature (r= 0.469) than HSI and WBGT. WBGT has high correlation withglobe temperature (r= 0.956) and natural wet bulb temperature (r= 0.877) so this findingcan prove that WBGT index shows higher heat stress than core body temperatures. thePearson correlation coefficient between HSI with relative humidity is r=0.619 and HSI hasmore correlation with relative humidity than core body temperature (r= 0.307) andWBGT(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 withhigh relative humidity and low air movement.

Keywords:

WBGTHeat StressCore BodyTemperatureHIS