What is smoke primarily composed of?

The primary composition of smoke includes unburned hydrocarbons, which are organic compounds that remain in the smoke after fuel combustion. When materials burn, they don't always combust completely; this incompleteness results in a release of unburned hydrocarbons alongside other byproducts. These compounds can be a significant portion of what makes up smoke and contribute to its toxicity and odor.

While carbon dioxide and water vapor do make up a considerable amount of the components released during combustion, they are not the primary constituents that define smoke itself. Similarly, while oxygen and nitrogen are present in the air and may be involved in the combustion process, they are not the primary elements that characterize smoke. Burnt fuel residues could also be found in smoke, but they are generally considered less significant compared to unburned hydrocarbons.