If evaporative cooling is reduced, say by high humidity, which effect, if any, does this have on firefighters?

When evaporative cooling is reduced due to high humidity, it significantly impacts the body's ability to regulate its internal temperature. Under normal conditions, sweating is an effective way for the body to cool down; as sweat evaporates from the skin, it dissipates heat and lowers body temperature. However, when humidity levels are high, the air is saturated with moisture, making it difficult for the sweat on the skin to evaporate. This means that the cooling effect is diminished, and the body can overheat more easily.

For firefighters, who are often engaged in physically demanding tasks while wearing heavy protective gear, maintaining a stable internal temperature is critical for safety and performance. High humidity can lead to heat stress, fatigue, diminished cognitive function, and potentially life-threatening situations if the body overheats. Therefore, it is crucial for firefighters to be aware of the impact of humidity on their ability to cool down and to take appropriate measures to stay hydrated and cool while on the job.