In the context of firefighting, what is 'backdraft'?

Backdraft refers to an explosive ignition of accumulated flammable gases in a tightly sealed environment, typically occurring when fresh air is introduced suddenly. This phenomenon often arises in structural fires where the oxygen supply is limited. As the fire consumes available oxygen, it can produce a build-up of hot, combustible gases. When a firefighter opens a door or a window, the influx of oxygen can ignite these gases almost instantaneously, resulting in a violent explosion.

Understanding backdraft is crucial for firefighters, as it poses a significant danger. Recognizing conditions that may lead to backdraft, such as high heat, smoky conditions, and a lack of visible flames, can help firefighters take necessary precautions to prevent such an event during firefighting operations. In contrast, the other options listed do not accurately describe the dynamics and hazards associated with backdraft.