Evaluating Heat Risk: Comparing On-Site WBGT Measurements Versus Smartphone Application Estimates

Exertional heat illness poses a significant risk for workers, athletes, and military personnel participating in outdoor activities during hot weather. An important component of heat safety is monitoring environmental conditions through heat stress indices like the wet bulb globe temperature (WBGT), which accounts for factors such as air temperature, humidity, wind, and sunlight, and adjusting activity as conditions get progressively hotter. On-site (OS) WBGT measurement devices are traditionally used, but phone applications (PAs) offering WBGT estimates have emerged as a potential alternative. This study compared WBGT estimates from a smartphone application with those from an OS WBGT device and their respective suggested activity modification categorizations. The findings indicate that, while PA WBGTs exhibited high correlation (r = 0.89) with OS devices, the smartphone application often reported cooler WBGTs and less-restrictive activity modifications than OS measurements. In light of these results, we recommend further validation of PA WGBTs prior to their adoption as a replacement for OS measurements.