What is the most immediate and dangerous consequence of suddenly introducing oxygen to a superheated, ventilation-limited compartment fire?

The most immediate and dangerous consequence of suddenly introducing oxygen to a superheated, ventilation-limited compartment fire is a backdraft. A superheated, ventilation-limited compartment fire describes a scenario where an enclosed space contains a fire that has consumed most of the available oxygen but still has abundant fuel. "Superheated" means the temperature within the compartment, including the accumulated gases and surfaces, is extremely high, often well above the ignition temperature of the unburnt fuel. "Ventilation-limited" indicates that there is insufficient oxygen to sustain complete combustion, leading to incomplete burning and the generation and accumulation of highly flammable, unburnt fuel gases and smoke (e.g., carbon monoxide, hydrocarbons). This creates a "fuel-rich" atmosphere inside the compartment, where there are plenty of fuel vapors but very little oxygen. When an opening is suddenly created, such as breaking a window or opening a door, fresh, oxygen-rich air rapidly enters this oxygen-depleted, superheated, fuel-rich environment. The incoming oxygen immediately mixes with the hot, unburnt fuel gases. Because these gases are already at or above their ignition temperature, they instantly and simultaneously ignite with explosive speed and force upon mixing with the newly introduced oxygen. This rapid combustion and expansion of gases create a violent pressure wave, often expelling flames, superheated gases, and smoke forcibly out of the opening. A backdraft is extremely dangerous due to its explosive nature, the rapid and widespread propagation of flames, and the intense heat generated, posing an immediate and severe threat to life and property.