What does the term "flashover" refer to in firefighting?

The term "flashover" refers to a critical phenomenon in firefighting where a fire rapidly spreads throughout a room or enclosed area due to the buildup of heat and combustibles. It occurs when the temperatures rise to the point that all combustible materials in the space ignite simultaneously, resulting in a sudden and intense increase in flames and thermal energy.

In understanding flashover, it is important to recognize that this event is characterized by the transition from a smoldering fire to an explosive full-room involvement, often occurring at temperatures between 1,100°F (593°C) to 1,200°F (649°C). This rapid spread poses extreme risks not only to the structure involved but also to firefighters, as conditions can change drastically within seconds. Recognizing the signs of impending flashover can be crucial for firefighting strategies and ensuring safety on the scene.

The other choices do not accurately define flashover. The point at which a fire starts refers to ignition, while the moment a fire is extinguished pertains to fire suppression efforts. The change in smoke color can provide valuable information about the fire's conditions, but it does not encapsulate the phenomenon of flashover itself.