What phenomenon occurs when all combustibles in a room ignite simultaneously?

Flashover is the correct phenomenon to describe the event when all combustibles in a room ignite at the same time. This typically occurs in a fully involved fire scenario where the temperature has risen significantly due to the heat produced by the flames, and all materials in the space reach their ignition temperature nearly simultaneously.

During flashover, the intense heat can cause compartment temperatures to soar, resulting in a rapid transition from a localized fire to one that engulfs the entire room. This rapid ignition is highly dangerous for firefighters and anyone within the structure, as it results in a significant increase in fire intensity and can lead to life-threatening conditions in a matter of moments.

Backdraft, ignition, and smoke explosion refer to distinct phenomena related to fire behavior. A backdraft happens when an oxygen-starved fire reignites explosively after fresh oxygen is introduced. Ignition refers to the process where a material begins to burn; it does not specifically involve all combustibles igniting at once. A smoke explosion can occur when unburned fuel (smoke) within a compartment ignites, causing a violent burst, but it does not denote the simultaneous ignition of all combustibles in a space.