The Limitations of WBGT Index for Application in Industries: A Systematic Review

The Wet Bulb Globe Temperature (WBGT) is still widely applied as a preliminary tool for evaluating heat stress. This index faces some limitations not considered yet. This systematic review was conducted aiming at highlighting some limitations for the development of the WBGT index.

The present study was organized using more extensive databases: PubMed, Google Scholar, Scientific Information Databases (SID), Elsevier, Web of Science, Scopus, Irandoc, Magiran, and Iran Medex. The used search terms were WBGT index, Heat stress, Thermal Stress, Heat strain, Wet Bulb Globe Temperature, Hot Condition, Occupational Health, and Occupational Exposure indices. In this study, 69 articles from 1950 to December 2021 were assessed.

The WBGT index, despite having some advantages, suffers limitations that should be considered for a more accurate estimate of thermal stress. This study pointed to the new limitations; including, the value of WBGT is not clear for persons whose working in a seated posture. The additional problem with the use of this index is that it is used for adapted people who have consumed enough water and salt, while in most hot working environments neither water nor salt is always readily available. Therefore, using this index will cause an error. Also, in heterogeneous environments, if the heat source is near the head or legs, a coefficient will not be applied to these regions. The results of the study demonstrate that, because of the limitations of the WBGT index, it is recommended that this index be used along with other indicators and physiological parameters to assess heat stress until more extensive studies are conducted in an attempt to improve and remove its limitations.