Practical on-site measurement of heat strain with the use of a perceptual strain index

Abstract

Objectives: There have been increased interests in research on quantifying heat strain of construction workers and formulating corresponding guidelines for working in hot weather. The aim of this study was to validate a subjective measurement tool, the perceptual strain index (PeSI), for measuring heat strain in real-work settings. Methods: A total of sixteen construction workers were invited to participate in the field surveys. Empiric-based human monitoring was carried out with simultaneous micrometeorological (wet-bulb globe temperature, WBGT), physiological (heart rate, HR), and perceptual (perceived exertion, RPE; thermal sensation, TS) measurements throughout the test. The relative heart rate (RHR), the physiological strain index (PSIHR), and the PeSI were then calculated accordingly. Results: The PeSI exhibited moderate correlations with WBGT and RHR (r = 0.42 and 0.40, respectively), which indicated the PeSI was sensitive to the variants of WBGT and RHR. The results of regression analysis indicated that the PeSI changed in the same general manner as the PSIHR, with a relatively large determination coefficient (R 2 = 0.67). The established perceptual strain zone illustrated that the PeSI ranging from 7 to 8 would be the exposure limit of construction workers in hot weather. Conclusion: The PeSI is a simple, robust, reliable, and user-friendly tool for heat strain assessment in occupational settings. The perceptual strain zone will provide practical guidelines for on-site heat strain monitoring for construction workers.