What is a backdraft?

A backdraft occurs when a fire consumes the available oxygen within a confined space, leading to incomplete combustion. When more oxygen suddenly enters the space—such as when a door or window is opened—the accumulated unburned gases can ignite explosively. This ignition typically creates a deflagration, a combustion process that propagates through the unburned gas mixture at a relatively low speed compared to a detonation.

This phenomenon is particularly dangerous because it can lead to rapid combustion and an explosive fireball. Understanding the dynamics of fuel, oxygen, and ignition sources is crucial for fire investigators in assessing fire behavior and determining the potential for backdrafts in fire scenarios. The other responses do not accurately describe the characteristics of a backdraft, as they pertain to different aspects of fire behavior.