What is the fire behavior phenomenon known as "backdraft"?

The phenomenon known as "backdraft" refers to an explosive ignition of accumulated gases within a structure that occurs when fresh oxygen is introduced, typically following a ventilation tactic. In situations where a fire has been smoldering and depleting the available oxygen, combustible gases can accumulate to a volatile level. When a door or window is opened—allowing oxygen to flow into the fire environment—this sudden influx can ignite the trapped gases, leading to a rapid and dangerous fire reaction, often resulting in an explosive force. Understanding this behavior is crucial for firefighting tactics, as it emphasizes the dangers associated with ventilation and the importance of controlling oxygen supply during a fire response to prevent such occurrences.