Which is a common indicator of backdraft conditions?

A common indicator of backdraft conditions is smoke that appears to be pressurized. During a backdraft situation, there is a build-up of unburned combustible gases within a structure that has limited oxygen supply. When these gases become superheated and the conditions change, such as by an increase in available oxygen, they can rapidly ignite. The smoke that is present in such a situation often appears to be pressurized due to the intense heat and the turbulent conditions within the structure. This characteristic is crucial for firefighters to recognize, as it signals a potential explosive situation upon entry or when windows or doors are opened.

Visibility, vigorous flame production, and broken windows may indicate fire or other hazardous conditions, but they do not specifically signal backdraft. For instance, good interior visibility often suggests a lack of smoke conditions that are typically present during a backdraft. Vigorous flame production can signify an active fire but may not necessarily indicate backdraft conditions, especially if there is adequate oxygen present. Similarly, while broken windows can be a sign of fire and heat, they do not specifically indicate backdraft; they can happen for other reasons, such as structure failure or as a result of thermal expansion. Thus, recognizing smoke that appears pressurized is key in identifying the risk