What factor contributes to backdraft in a ventilation-limited fire?

In a ventilation-limited fire scenario, backdraft occurs due to the sudden introduction of oxygen into an environment that has accumulated combustible gases at high temperatures. When the fire is starved of oxygen, the combustion is incomplete, leading to the generation of flammable gases, which can build up in the space. If ventilation is increased—such as by opening a door or a window—this sudden influx of oxygen can lead to a rapid combustion event, resulting in a backdraft.

In this context, increasing ventilation is a critical factor that can trigger backdraft because it allows the accumulated gases to ignite explosively when a sufficient quantity of oxygen is introduced. Understanding this process is essential for firefighters to prevent dangerous situations when entering a structure that may be affected by backdraft.

The other factors contribute differently to fire dynamics but do not specifically lead to backdraft in a ventilation-limited scenario as significantly as an increase in ventilation does.