Which environmental factors increase the risk of heat stress during rehab?

• A. High ambient temperature, high humidity, radiant heat from the incident
• B. Low ambient temperature, high humidity, shade from trees
• C. Low humidity, cool rain, reflective gear cooling
• D. Windy conditions, low humidity, drinking cold water

Answer: (A)

The key idea is how environmental heat load overwhelms the body's ability to cool during rehab. When the air is very hot, the body has less gradient to lose heat to the surroundings, so heat builds up more easily. High humidity further reduces cooling by evaporation—sweat stays on the skin instead of evaporating, so evaporative cooling is limited. Radiant heat from the incident adds direct heat energy to the body, increasing core temperature. Together, these factors create a scenario where even resting firefighters can quickly become heat-stressed.

Other conditions that involve cooler temperatures, shade, wind, or accessible cooling help the body shed heat, so they don’t elevate risk in the same way.