What is the smoke production like during the free-burning phase?

During the free-burning phase of a fire, the flames consume the available fuel and oxygen efficiently. As a result, there is initially a considerable amount of smoke generated due to the combustion of organic materials and other combustion by-products. However, as the fire continues to burn, the oxygen levels begin to decrease, which alters the combustion process. In this phase, while there is still smoke production, it tends to become more pronounced as the fire struggles to maintain efficient combustion due to the limited oxygen. This decrease in oxygen can lead to incomplete combustion, which often results in an increase in smoke production. Therefore, while there is limited smoke initially, it begins to increase significantly as the availability of oxygen diminishes.