What occurs during the decay stage of a fire?

During the decay stage of a fire, the combustion process is reaching its limits, primarily due to the diminishing supplies of fuel and oxygen. As a fire burns, it consumes these critical resources. In the decay stage, the burning material is largely exhausted, leading to a reduction in both available fuel and the oxygen needed to sustain the fire. This stage typically follows the fully developed stage, where heat and flames are at their maximum, indicating that the fire has consumed most of its immediate fuel and is unable to sustain its previous intensity.

In contrast, the ignition stage marks the very beginning of the fire, and during this phase, fuel supply and oxygen are still adequate. A fully developed fire indicates that the fire has reached its peak, which also does not align with the characteristics of the decay stage. Lastly, an increase in fuel supply contradicts the essence of the decay stage, where resources are becoming limited, thus contributing to the fire's eventual suppression.