What are the components of a WBGT (Wet Bulb Globe Temperature) index, and what does it indicate?

• A. Humidity, room temperature, and altitude; indicates fire risk.
• B. Natural wet-bulb temperature, globe temperature, and dry-bulb temperature; indicates heat stress risk and guides work-rest cycles.
• C. Dry-bulb, dew point, and CO2 concentration; indicates ventilation quality.
• D. Light level, noise level, and humidity; indicates comfort.

Answer: (B)

WBGT is a heat-stress index that blends different aspects of the environment to reflect how hot it feels to a person and how much heat stress they’re likely to experience. The three components are natural wet-bulb temperature, which captures evaporative cooling and humidity effects; globe temperature, which measures radiant heat from the surroundings (like sun and hot surfaces); and dry-bulb temperature, the plain air temperature. By combining these, WBGT assesses the overall heat load a person faces and guides practical safety decisions such as work-rest cycles, hydration needs, and protective measures. The other options mix in humidity, dew point, CO2, or simply omit the radiant heat aspect, so they don’t accurately represent what WBGT measures or how it’s used to indicate heat-stress risk.