What danger is suggested by the observation of smoke puffing in and out of a structure?

The observation of smoke puffing in and out of a structure is indicative of backdraft conditions. Backdraft occurs when a fire has limited ventilation and is using up most of the available oxygen. When a fire suddenly gets oxygen, such as when a door or window is opened, it can lead to an explosive ignition of the accumulated unburned gases. The smoke movement reflects the pressure changes inside the structure as hot gases push smoke outward and then draw it back in when oxygen levels fluctuate. This behavior is a critical warning sign for firefighters, indicating that the fire could transition to a more dangerous stage if ventilation is not carefully controlled. Recognizing this pattern is essential to prevent catastrophic outcomes while entering or attempting to suppress the fire.