Validation of a temperature-humidity index (Humidex) in evaluating heat stress at a tile factory in Iran.

Background: Several heat indices have been developed in industrial health, but each has its limitations.

Objective: The objective of this article is to determine the validity and applicability of a temperature-humidity index, named Humidex compared with the Standard Wet-Bulb Globe Temperature (WBGT) index (ISO 7243).

Method: This cross-sectional study was conducted in the summer of 2019, in a tile factory in the west of Iran. 59 measurements were performed in 8 different workstations. Environmental parameters including natural wet bulb temperature (Tnw), dry bulb temperature (Ta), globe bulb temperature (Tg), and heat stress (WBGT) were measured. Humidex was calculated according to an equation. SPSS software (version 16) was used for data analysis.

Results: There was a high correlation between Humidex and WBGT in the estimation of heat stress (R=0.912, P<0.001). The Kappa Coefficient between Humidex and WBGT was 0.298, P=0.001.

Conclusion: Humidex is highly correlated with WBGT. Humidex can be used instead of the WBGT index, especially in hot and humid environments.