Smoke and soot particles are the visual by-products of incomplete combustion.
Combustion is the self-sustaining process of rapid oxidation. Three elements required for combustion: fuel, oxygen and heat. Fire is the result of this combustion reaction. The two terms fire and combustion are not the same, but sometimes are used interchangeably.
Rapid oxidation is known as combustion, while the slow oxidation that most people are familiar with is called rust. Combustion is rapid oxidation, which produces heat and smoke. Typically the more kinds of substances involved in combustion, the more complex the odors and residues will become. One of the components of smoke is carbon.
The quantity of available oxygen can affect combustion temperature and the amount of smoke particle residue produced. Incompletely combusted substances also produce odors.
The size of particulate matter (PM) produced by fire is extremely small — particles range from 0.1 to 4 micrometers (or microns) in diameter. A micron, or µ, is a small unit of measure and is invisible to the naked eye. One micron is equal to 1/25,000 of an inch or 1/1,000,000 of a meter. A particle of incomplete combustion, or PIC, is the industry term referring to soot, smoke residue and any other related combustion by-product.
In addition to carbon particles, there are also gasses associated with combustion. Volatile organic compounds (VOCs) like polycyclic aromatic hydrocarbons (PAHs) are commonly produced during and following a fire.
Both soot particles and PAHs have been reported to be carcinogenic. For this reason, all personnel at the fire damage site must wear properly fitted respirators with HEPA-rated filters capable of removing VOCs. Additionally, HEPA air scrubbers utilizing activated carbon filtration should be placed within these spaces to reduce airborne contaminants.
