The decay phase of fire development is described as which?

The decay phase of fire development is described as which?

• A. The stage where smoke hangs low to the ground due to cold air.
• B. The controlled and coordinated removal of heat and smoke from a structure.
• C. The fourth stage that results from a decrease in the fuel load or available oxygen.
• D. The initial ignition of the fuel.

Answer: (C)

Fire development moves through stages, and the decay phase is the fourth stage. It happens when the fire runs out of sufficient fuel to burn and/or the available oxygen is reduced, so the heat release drops and flames diminish. Even though pockets of fuel and smoldering may continue, the overall intensity declines as the fire can no longer sustain itself with the remaining fuel and air. This description—the fourth stage resulting from a decrease in fuel load or available oxygen—best fits the decay phase. The other ideas describe smoke movement due to air layering, heat and smoke being removed through ventilation, or the initial ignition, none of which define this late-stage decline in energy output.