What phenomenon occurs in poorly ventilated spaces where a fire smolders due to insufficient oxygen?

The phenomenon that occurs in poorly ventilated spaces where a fire smolders due to insufficient oxygen is known as backdraft. This situation arises when a fire has consumed most of the available oxygen in a confined space, causing it to smolder rather than burn actively. When additional oxygen is suddenly introduced—such as when doors or windows are opened—the smoldering fire can rapidly ignite, leading to explosive flaming combustion.

Understanding backdraft is critical for fire safety directors, as it highlights the dangers of ventilation during firefighting operations. They must be aware of the signs indicative of backdraft conditions, such as smoke that is thick, dark, and possibly being sucked back into a fire area, or a sudden cessation of visible flames. Proper strategies for dealing with ventilation in high-rise buildings, especially during rescue operations, are essential to prevent this dangerous phenomenon.