Which factor directly affects how long a worker can stay in hot conditions according to guidelines?

• A. Dry bulb temperature
• B. Relative humidity
• C. Airflow rate
• D. Wet bulb temperature

Answer: (D)

Understanding heat exposure limits hinges on the body's ability to shed heat through evaporation. Wet bulb temperature directly measures this cooling potential because it combines air temperature with moisture and how easily sweat can evaporate. When humidity is high, evaporation slows, so the body loses cooling efficiency and the safe duration in hot conditions shortens; a higher wet bulb temperature signals tighter limits and shorter allowable exposure. While dry bulb temperature, relative humidity, and airflow influence heat stress, the direct factor that dictates how long a worker can stay in heat according to guidelines is the wet bulb temperature, often used as part of the WBGT measure.