It releases energy in the form of heat, which destroys the organic matter. Before going on to more about combustion, you need to know something about some other hydrocarbons. If you are not familiar with them, you should click here to find a discussion of their properties. The temperature must be high enough that the bonds can be broken. The organics must be subjected to these conditions for a sufficiently long time.
Several seconds is a minimum.
If these conditions are not met, some of the organic compounds will not be broken down completely. In this case, some of the organics are expelled out the smokestack unchanged, and others are partially broken down, but it is not always clear by how much they change. In addition, reactions between the incomplete combustion products can result in other dangerous chemicals. Incomplete combustion does not reduce the health hazard these compounds cause. It puts dangerous compounds into the atmosphere, where they are spread over large areas by the winds.