Tehran University of Medical Sciences International Journal of Occupational Hygiene 2008-5109 13 4 2021 12 30 365 381 Farideh Golbabaei Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Akbar Ahmadi Asour Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran/ Department of Occupational Health, School of Health, Sabzevar University of Medical Sciences, Sabzevar, Iran Sepideh keyvani Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Malihe Kolahdoozi Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Mahdi Mohammadiyan Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Fatemeh Fasih-Ramandi Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran 2021 10 23 2021 12 20 Abstract Introduction: The Wet Bulb Globe Temperature (WBGT) is still widely applied as a preliminary tool for evaluating the heat stress. This index faces some limitations not considered yet. This systematic review was conducted aiming at highlighting some limitations for development of the WBGT index. Method: 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 2020 were assessed. Conclusion: The WBGT index, despite having some advantages, suffers limitations which 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. In addition, this index is used for adapted people who have used enough water and salt while water and salt are not always available to workers in all hot working environments, hence using this index will come with an error. Also, in heterogeneous environments, if the heat source is at the height of the face and legs, no coefficient would be taken into account for these areas. https://ijoh.tums.ac.ir/index.php/ijoh/article/view/550 https://ijoh.tums.ac.ir/index.php/ijoh/article/download/550/793