What does the term "backdraft" refer to in fire behavior?

The term "backdraft" in fire behavior specifically refers to a sudden and explosive ignition of flammable gases that have built up in a space, which occurs when oxygen is introduced into an area previously deprived of it. This situation often arises in enclosed spaces where a fire has been smoldering without sufficient oxygen flow, leading to high concentrations of unburned combustible gases. When a door or window is opened, this influx of oxygen can create a rapid increase in the fire's intensity and result in a dangerous explosion.

This phenomenon is particularly hazardous to firefighters and anyone in the vicinity, as it can cause severe injuries and complicate fire suppression efforts. Understanding backdraft is crucial for fire safety and firefighting tactics, as recognizing the signs and risks associated with it can help responders take necessary precautions to avoid triggering such an explosive event.