What index should workplaces use to monitor conditions that may result in heat-related illness?
Occupational (Industrial) hygienists recommend using the Wet Bulb Globe Temperature (WBGT) index to measure workplace conditions. This method closely relates to the human body’s response to heat. The WBGT measurement takes into account air temperature, air movement, radiant heat and humidity. There are direct-reading WBGT meters. These are also called “heat-stress indicators,” commercially available. The WBGT measurements can then be related to the physical demands of the job. Only qualified professionals, whether they be in-house staff, consultants, or from the local occupational health and safety regulatory agency, should perform the measurement. Direct comparison between WBGT and humidex is not possible–there are no conversion tables or mathematical formulas to do such conversions. However, one can estimate WBGT and humidex for a given ambient air temperature and humidity when radiant heat sources (hot and cold surfaces) are absent and air movement is less than 0.5 m/sec. (100 feet
