Which hazard is identified as dangerous to firefighters?

• A. Rollover
• B. Collapse
• C. Backdraft
• D. Flashover

Answer: (B)

Structural failure is a constant danger in fires because heat weakens the supporting elements of a building. When floors, roofs, or walls lose strength, they can give way suddenly, trapping or crushing anyone inside. That immediate, potentially total loss of support is what makes collapse uniquely deadly for firefighters: it can occur with little or no warning, and the debris field can bury rescuers and prevent escape.

Signs to watch for include sagging or bulging floors and ceilings, new and widening cracks in walls, leaning or shifting structural members, creaking or groaning noises, and rapidly changing conditions in the fire area. Because of this risk, crews establish a collapse zone and limit exposure to areas that show signs of structural weakness, using careful size-up and controlled operations to avoid being caught in a sudden failure.

Rollover, backdraft, and flashover are serious fire behavior hazards that require specific tactics, but collapse is the hazard that directly embodies the threat of a structure failing and endangering firefighters from within.