How does high humidity impact smoke and fire gases during a fire?

High humidity has a significant effect on the behavior of smoke and fire gases during a fire, primarily by keeping combustion products closer to the ground level. When humidity is high, the air is already saturated with moisture, which increases the density of the air. This denser air can inhibit the upward movement of smoke, as the buoyancy that typically allows hot smoke to rise is reduced. Consequently, the smoke and other combustion products tend to accumulate closer to the ground, potentially creating more hazardous conditions for occupants and firefighters alike.

In an environment of high humidity, the reduced movement of these gases can also impact visibility and air quality, making situations more dangerous. Understanding this behavior is crucial for firefighters; it influences tactical decisions regarding ventilation, search and rescue operations, and where to position oneself for safety.