Understanding Backdrafts: The Hidden Explosion🔥 What you can’t see can still explode. Always respect the signs — and let trained firefighters handle enclosed fire situations. Backdrafts are among the most dangerous fire phenomena firefighters can encounter. They occur when a fire has been smoldering in a closed or confined space, running out of oxygen. When fresh air suddenly enters, oxygen mixes with superheated, unburned gases, triggering a violent explosion that can blow out windows, doors,