Heat Stress Measurements

Many employees work at elevated temperatures in the work environment with potential exposures for heat related illnesses. Most heat stress exposures can be effectively managed with a program that educates workers on symptoms of heat related illnesses and corrective actions. Exposures can also be managed through effective engineering controls that are designed for the heat sources present in the workplace. While it is tempting to add fans and increase air movement for tasks with elevated temperatures, often times this approach is the least effective way to address the heat sources actually present. To effectively manage heat exposures in the work place, a heat stress survey should be conducted to identify heat sources that are contributing to employee exposures.

Heat Stress measurements can be readily made using a Wet Bulb Globe Temperature (WBGT) instrument to identify heat sources for effective control. A WBGT instrument uses a combination of temperature sensors to measure the Wet Bulb (WB) temperature, Globe Temperature (GT) and Dry Bulb (DB) temperature. A comparison of those temperatures can give indications on the types of heat sources present in the workplace. Controls for a work environment with a high DB temperature in excess of 95° F will need different heat controls than a work environment heavily influenced by radiant heat as evidenced by a high GT measurement. After identifying the types of heat sources present and employee work patterns and interactions, an effective Heat Stress Control program can be implemented to minimize risks for heat related illnesses.