The WBGT (Wet-Bulb Globe Temperature) index was initially developed for monitoring in US military training centres and then extended to workplaces and sports activities. It is proposed in the international standard ISO 7243 and has been adopted by many governmental authorities, such as OSHA (US Occupational Safety & Health Administration), SMA (Sports Medicine Australia) and the Japanese Occupational Health Association, to determine permissible limits of thermal exposure in occupational and sports environments or other physical activities.

Applications of the heat stress index include places such as:

construction sites, iron and steel foundries, ceramics factories, glazing plants, boiler rooms, mines, military exercises, marathons, beach activities, etc.