Which scenario is a common warning sign that backdraft may be imminent?

• A. Thick dark smoke pushed from a doorway with little flame present.
• B. Fire extinguished by water.
• C. A quick increase in air supply with visible flames.
• D. Smoke is clear and heat is low.

Answer: (A)

Backdrafts occur when a room fills with hot, fuel-rich gases and little oxygen, so the fire smolders rather than roars. The warning you’re most likely to notice is thick, dark smoke being pushed out of a doorway while there’s little visible flame. That heavy, pressurized smoke means the space is loaded with heat and fuel gases, and a sudden influx of air can cause those gases to ignite violently once oxygen mixes in. The other scenarios don’t show that same pre-ignition gas buildup: water extinguishing a fire isn’t a sign of an imminent backdraft; a quick burst of flames with more air coming in can indicate rapid fire growth or flashover after air entry, not the impending backdraft condition; and clear smoke with low heat suggests cooler, less intense conditions.