What describes the physical reaction that can occur if an oxygen-depleted environment suddenly receives a surge of air?

The phenomenon described is a backdraft, which occurs when an oxygen-depleted environment, such as a compartment that has experienced a fire and has consumed most of the available oxygen, suddenly receives a surge of air. When fresh air enters this environment, the previously smoldering combustion can ignite explosively since the fire can suddenly become starved for oxygen. This influx allows the accumulated flammable gases to ignite all at once, leading to a rapid increase in fire intensity.

Understanding backdraft is critical for firefighting operations. Firefighters must be aware of the symptoms of potential backdraft conditions, such as smoke that is pushed out of openings and a darkened, heat-saturated environment, so they can take appropriate precautions before introducing fresh air into an area where a fire has occurred. This knowledge helps to prevent dangerous flare-ups and ensures the safety of both firefighters and civilians.