The Assessment of Heat Stress and Heat Strain in Pardis Petrochemical Complex, Tehran, Iran

Heat stress is well recognized among the hazardous physical agents that might be present during work. This study aims to compare WBGT index at acclimated and unacclimated people to permissible threshold limit value and study the differences between physiological parameters at them. Twenty one healthy men were participated in the study. All of the subjects were monitored in two different weather and working conditions: the Kar site (the work site) and the Paziresh site (the office site). A set of physiological and environmental parameters, namely heart rate, blood pressure, skin temperature and deep body temperature, dry temperature, wet natural temperatures, radiant temperature and relative humidity were measured and monitored simultaneously. The acclimated subjects were all of the ammonia-phase workers working in the hot-humid worksite. Other participants were selected from the work sites without risk of heat stress. Mean value of WBGT / TLV was less than one for the both acclimated and unacclimated groups at Paziresh site, while this value was more than one at Kar site and also mean of WBGT. For two groups, TWA / TLV were less than one during the working day. Mean physiological parameters were not significantly different between the acclimated and unacclimated subjects at both sites. However, physiological parameters such as heart rate and core body temperature showed statistically significant difference between two groups at Kar. Both groups of Paziresh were not exposed to heat stress, but Kar's operators continued work under conditions of heat stress.