What occurs during a backdraft phase of a fire?

During the backdraft phase of a fire, conditions can become critically dangerous as a buildup of flammable gases occurs in an enclosed space. When oxygen is suddenly reintroduced—such as through an opening created by a firefighter breaking a window or opening a door—the accumulated gases ignite explosively. This event is characterized by a rapid and violent combustion, where the fire fully involves as ignition occurs throughout the previously smoldering gases.

Understanding this phenomenon is essential for fire protection professionals, as it underscores the importance of ventilation and the risks associated with introducing oxygen into a fire environment without proper preparation and awareness of the potential for backdraft.