The relationship between observational – perceptual heat strain evaluation method and environmental / physiological indices in warm workplace

Objective: heat stress is a hazard common in the industries. several indices are used to evaluate heat stress. but most of the indices need expensive instruments especially in developing countries. the purpose of this research was to determine validation of an observational – perceptual method as heat strain score index (hssi) in warm conditions. methodology: this research was performed on 145 healthy subjects. oral temperature and heart rate were measured by a heart rate monitoring (polar rs100 model) and oral thermometer (tb100 model) at rest and field. wet bulb globe temperature (wbgt) were also recorded and hssi questionnaire was completed simultaneously. data was analyzed by pearson correlation test and regression analysis. results: pearson correlation test showed a significant correlation between the hssi values and psi values (r = 0.397, p < 0.001). pearson correlation between wbgt values and physiological strain index (psi) values observed a significant association (r = 0.57, p < 0.001) a moderate correlation between the hssi values and oral temperature was also observed(r = 0.556). conclusion: this research showed that heat strain score index, in comparison with wbgt index, had a higher correlation with psi. according to hssi moderate correlate with others valid indices is economical and also easier to use. hence, hssi can be used as the heat strain screening tool in the warm workplace when other heat stress evaluation methods are not available.