Comparison of Correlation between Wet Bulb Globe Temperature، Physiological Strain Index and Physiological Strain Index Based on Heart Rate with Heart Rate and Tympanic Temperature on Workers in a Glass Factory

Backgrounds and Heat stress is one of the main and the most common problems in the work environments. Extreme heat exposure can cause different clinical symptoms، including headache، nausea، vomiting. The aim of this study is to compare the correlation of Wet Bulb Globe Temperature، Physiological Strain Index and Physiological Strain Index based on heart rate heat stress indices with tympanic temperature and heart rate among the workers of a glass factory. This cross- sectional study was conducted in a glass factory located in Tehran. 72 male subjects were participated in the study. Atmospheric parameters including dry temperature، natural wet bulb temperature and globe temperature were measured to determine the heat stress indices. Tympanic temperature and heart beat rates were also measured. The data were statistically analyzed using the Pearson and Spearman correlation as well as the linear regression tests. The correlation between tympanic temperature and heart rate with heat stress indices was significant (p-value<0. 05). The poly-nominal correlation (R2) between Wet Bulb Globe Temperature Index with heart rate and tympanic temperature was 0. 208 and 0. 214 respectively. This correlation between Physiological Strain Index with heart rate and tympanic temperature was 0. 423 and 0. 701 respectively. The correlation between Physiological strain index based on heart rate with heart rate and tympanic temperature was 0. 579 and 0. 068 respectively. The Physiological Strain Index heat stress index had higher correlation with measured physiological parameters in this study.