Introduction: The incidence of heat stress is one of the most common problems in work
environments as well as many different industries. The exposure of workers to heat results
in heat strain. The purpose of the
present study was to validate the Perceptual Strain Index through determining its relationship to the Physiological Strain
Index and the Wet Bulb
Globe Temperature Index under hot laboratory conditions.
Materials and Methods: The present cross-sectional study was
conducted on 15 men in five different temperature conditions (21, 24, 27, 30
and 35ºC) in a climate chamber and on the treadmill with three different
activity levels –light (2.4km/h), medium (4.8km/h) and heavy (6.3km/h).
Participants' heart rate and oral temperature were measured in order to
calculate the Physiological Strain Index, and their thermal sensation and the rate of
perceived exerted activity were measured for calculating the Perceptual Strain
Index. The correlations between the indices were then evaluated using Pearson's
correlation test and the regression analysis.
Results: Pearson's correlation test showed a significant correlation between
the Perceptual Strain Index and the Physiological Strain
Index (P=0.001 and r=0.94). The Perceptual Strain Index was also found to have a significant
correlation with oral temperature and heart rate (p=0.001
and r=0.78 (p=0.001 and r=0.90). In addition, a significant correlation was found
between the Perceptual Strain Index and the Wet Bulb Globe Temperature Index (p=0.001 and
r=0.71) however, no relationship was observed between the
Perceptual Strain Index and the Body Mass Index (p=0.79 and r=0.0009).
Conclusion: The findings of the
study showed that the Perceptual Strain Index can be used for evaluating heat
strain in the absence of access to other methods of evaluating heat stress as
it has an acceptable correlation with valid indices of heat stress.
