Which phenomenon might be signaled by smoke being drawn back into a structure?

The phenomenon indicated by smoke being drawn back into a structure is often associated with a risk of explosion. When smoke is pulled into a building, this can suggest that a significant vacuum is being created, potentially due to a fire that is consuming available oxygen inside the structure. If the conditions are right, and flammable materials are present, this vacuum can lead to an explosive backdraft.

A backdraft occurs when a sudden influx of oxygen meets a smoldering fire that has been deprived of air, which can very quickly lead to an explosive reaction. This is a critical concern for firefighters and safety officers, as understanding the signs of potential explosions, such as smoke being drawn backward, can help in strategizing their response to contain and extinguish the fire safely. Recognizing this phenomenon is essential for ensuring the safety of both the responders and individuals within or near the structure.