Backdraft: One of Firefighting’s Most Dangerous Phenomena A backdraft happens when a fire, starved of oxygen, builds up gases and heat — then suddenly explodes when fresh air rushes in. It's violent, fast, and deadly. Signs to watch for: Smoke-stained windows Puffing smoke from cracks Smoke that looks dense and "breathing" Low, rumbling sounds behind doors Slow down. Read the building. Control ventilation. In this job, recognizing the signs could save your life and your crew’s. Stay aggressive —