Which index is used to measure environmental heat stress according to BE Roles and Thermal Stress?

• A. Wet Bulb Globe Temperature (WBGT)
• B. Sound Level Meter readings
• C. Air velocity
• D. Fire Index

Answer: (A)

Measuring environmental heat stress uses an index that captures how hot it feels by combining several environmental factors. The Wet Bulb Globe Temperature (WBGT) does this by integrating dry-bulb air temperature, wet-bulb temperature (which reflects humidity and evaporative cooling potential), and globe temperature (which represents radiant heat from sun and surroundings). This combination provides a single value that correlates with human heat stress risk under realistic working conditions, guiding safe work/rest cycles, hydration, clothing, and shading. That makes WBGT the best choice for BE roles and thermal stress, because it accounts for temperature, humidity, airflow’s cooling effect, and radiant heat—not just one aspect. In contrast, sound level meter readings relate to noise, not heat stress; air velocity alone is only a factor and doesn’t summarize overall risk; and the Fire Index concerns fire danger, not human heat stress.