During which phase does smoke production begin to increase significantly?

The Free-Burning Phase is characterized by a significant increase in smoke production due to the rapid combustion of fuels. During this phase, the fire has enough oxygen and heat to sustain a more vigorous and uncontrolled burn, leading to the release of larger quantities of smoke and gases. This phase follows the Incipient Phase, where the fire is just beginning to develop, and smoke production is minimal.

In the Free-Burning Phase, the fire reaches its peak intensity, and the materials involved are undergoing thorough and fast combustion, leading to the generation of more smoke. The factors that contribute to the increase in smoke include the type of fuels burning, the amount of available oxygen, and the overall heat of the fire. As the fire grows, it consumes more fuel, which directly correlates to increased smoke and particulate matter being produced.

In contrast, the Incipient Phase represents the initial development of the fire with limited smoke as the materials start to ignite. The Smoldering Phase occurs when the fire has reduced intensity and is more controlled, leading to less smoke production. The Extinguished Phase signifies that the fire has been fully put out, resulting in no smoke generation. Thus, the Free-Burning Phase is indeed the correct phase during which smoke production begins to significantly escalate