Investigating the Levels of Thermal Stress in Kerman City in 2016 Using Thermal Indices: WBGT, ESI, HI, HSI, and SWreq

Document Type: Original Article


1 Assistant Professor, Department of Occupational Health, School of Public Health, Kerman University of Medical Sciences, Kerman, Iran

2 Assistant Professor, Department of Occupational Health, School of Public Health, Urmia University of Medical Sciences, Urmia, Iran

3 Student Research Committee, Kerman University of Medical Sciences, Kerman, Iran

4 Associate Professor, Department of Occupational Health, School of Public Health, Kerman University of Medical Sciences, Kerman, Iran

5 Occupational Health Engineering, Shiraz University of Medical Sciences, Shiraz, Iran

6 Assistant Professor, Department of Public Health, Faculty of Health, Lorestan University of Medical Sciences, Lorestan, Iran


Background:Thermal stress may have numerous harmful effects on human health. This study aimed at investigating thermal stress in the city of Kerman, Iran.
Methods:In this descriptive-analytical study, thermal stress was assessed from 6 AM to 9 PM in 2016 using four thermal stress indices including wet-bulb globe temperature (WBGT), environmental stress index (ESI), Humidex, heat stress index (HSI), and Required Sweat Rate (SWreq). Necessary data were collected from the meteorological organization of Kerman. Pearson’s correlation coefficient and linear regression were used to examine the relationships among thermal stress indices and environmental parameters. All analyses were performed using SPSS version 22.
Results: Based on the results, the highest correlation coefficients were observed between ESI and WBGT (r = 0.99), Humidex and ESI (r = 0.96), Humidex and WBGT (r = 0.97) and SWreq and HSI (r = 0.99). On the other hand, thermal stress indices had significant relationships with environmental parameters including wind speed, air temperature, and relative humidity (P < 0.05).
Conclusion: All indices had strong and significant associations with one another. WBGT, HSI, and Humidex demonstrated similar thermal sensations. Furthermore, according to the obtained values of ESI, Humidex, and WBGT, people enjoy thermal comfort in all months of the year (save for January as judged by the obtained WBGT value). Thus, the climate of this city poses no threat to people’s thermal comfort.


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