Development and Validation of a Questionnaire for Preliminary Assessment of Heat Stress at Workplace

Habibollah Dehghan, Seyed Bagher Mortzavi, Mohamad Javad Jafari, Mohamad Reza Maracy


Background: Current heat stress indices are not completely suitable for heat strain screening in developing countries due to their inherent and applied limitations. The aim of this study was development of a questionnaire method entitled "Heat Strain Score Index" (HSSI) in order to perform a preliminary assessment of heat stress at work.

Methods: This research included six phases (i) Item generation (ii) Content validity (iii) Reliability analysis (iv)Structure validity (v) Concurrent validity and (vi) Classification of thermal risk level. In item generation phase, 40 items were identified to have impact on the heat strain. Content validity was evaluated by occupational health specialists.

Results: In consistency assessment, Cronbach’s coefficient (α) of items was 0.91. Exploratory factor analysis on items HSSI draft identified four subscales which explained 71.6% of the variance. Correlation between the HSSI score with aural temperature was 0.73. Cut-off point; sensitivity and specificity for upper no thermal strain zone were 13.5, 91% and 50%, respectively. Whereas Cut-off point, sensitivity and specificity for lower thermal strain zone were 18, 86% and 73%.

Conclusions: The results showed that 18 variables that were measurable through subjective judgment and observation in the HSSI scale covered heat stress key factors. This scale demonstrated reliability and initial validity in scale were suitable. Therefore HSSI scale for primary evaluation heat stress is appropriate.


Heat Stress Evaluation; Aural Temperature; Reliability; Validity; Heat Strain Score Index

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