Dangers in cellars

Firefighters can die in cellars from carbon monoxide accumulation due to incomplete combustion, from oxygen depletion due to flash fires,
from drowning in water-filled cellars, from breathing heavier-than-air gases that accumulate there and from flammable gas explosions during fire.

Some cellars are more dangerous than others are. A cellar that's completely below grade without windows is more dangerous than a cellar that's only partially below grade or one that has windows to provide ventilation. Cellars in high-rise buildings do not have windows. Sub-cellars, the most dangerous type of below-grade area, have no windows and are two stories below the street level, directly below the cellar.

A cellar becomes more dangerous after the fire has been extinguished. Smoldering embers generate carbon monoxide. Always ventilate and wear masks during cellar overhaul to prevent death from carbon monoxide inhalation.

• Vincent Dunn is a retired FDNY Deputy Chief. For more tactical advice and tips, go to Vincentdunn.com. For lecture information, call 1-800-231-3388.