Which phenomenon occurs when all combustible material in a room ignites simultaneously?

The phenomenon that occurs when all combustible material in a room ignites simultaneously is known as flashover. This event typically happens when the temperature in the room reaches a point where the heat is sufficient to cause the majority of the combustible materials present to ignite quickly and almost instantaneously, leading to a rapid and intense fire spread.

Flashover generally occurs during a fire when it has been burning long enough for the heat to accumulate and the air temperature rises significantly, often exceeding 1000 degrees Fahrenheit (approx. 538 degrees Celsius). At this critical point, flammable gases released by burning materials can ignite, resulting in a dramatic increase in fire intensity and posing extreme hazards to anyone in the area.

Understanding flashover is crucial for fire investigators and responders as it can dramatically change the dynamics of a fire scenario, often determining the strategy for fire suppression and rescue operations. Recognizing the signs that lead up to a flashover, such as darkening smoke conditions and rapid temperature increases, can be vital in assessing fire behavior and improving safety awareness.