Which environmental factor increases risk for heat-related emergencies?

• A. High humidity
• B. Low humidity
• C. Cold wind
• D. Snow

Answer: (A)

High humidity. When the air is humid, sweat doesn’t evaporate from the skin as quickly, and evaporation is the body's main way of cooling itself. If sweat can’t evaporate efficiently, the body loses less heat, so core temperature rises more readily during heat exposure or physical exertion. That combination makes heat-related illnesses, like heat exhaustion or heat stroke, more likely. A hot, humid day can feel much hotter than the same temperature with low humidity because the heat index is higher and cooling is less effective. In contrast, low humidity actually helps with cooling since evaporation occurs more readily, and cold wind or snow are not factors that increase risk for heat-related emergencies.