Backdraft fires are very dangerous, often surprising even experienced firefighters.
A backdraft is a phenomenon in which a fire in an enclosed area has consumed all available oxygen and appears to be dormant, but then suddenly explodes when more oxygen is made available, typically because a door or window has been opened.
The following videos describe and show backdrafts in a controlled environment. These videos use a special camera to record at exceptionally high speeds, which can then be slowed down to present unusual perspectives on any motion, in this case, explosive backdrafts.
The most common tactic used by firefighters to defuse a potential backdraft is to ventilate a room from its highest point, such as by chopping a hole in a roof or breaking a high window, which allows the heat and smoke to escape without igniting. Or, if this does ignite a backdraft, the firefighters are trained to be positioned out of harm’s way. Although you will note in the first video below, even a professional firefighter almost walked directly into an unexpected explosion.
As stated in the videos, do not try this at home!
If firefighters discover a room pulling air into itself, for example through a crack, they generally evacuate immediately, because this is a strong indication that a backdraft is imminent. Due to pressure differences, puffs of smoke are sometimes drawn back into the enclosed space from which they emanated, which is how the term backdraft originated.