Soot

A common feature of the definitions is that soot is composed largely of carbon based particles resulting from the incomplete burning of hydrocarbons or organic fuel such as wood.

[8][6] In some definitions, black carbon also includes charcoal, a type of matter where the chunks tend to be too large to have an aerosol form as is the case with soot.

Soot in very low concentrations is capable of darkening surfaces or making particle agglomerates, such as those from ventilation systems, appear black.

[citation needed] However, the order of sooting tendencies of the aliphatics (alkanes, alkenes, and alkynes) varies dramatically depending on the flame type.

[15][16] The Intergovernmental Panel on Climate Change (IPCC) adopted the description of soot particles given in the glossary of Charlson and Heintzenberg (1995), "Particles formed during the quenching of gases at the outer edge of flames of organic vapours, consisting predominantly of carbon, with lesser amounts of oxygen and hydrogen present as carboxyl and phenolic groups and exhibiting an imperfect graphitic structure".

[17] Formation of soot is a complex process, an evolution of matter in which a number of molecules undergo many chemical and physical reactions within a few milliseconds.

[1][18] The PAHs in soot are known mutagens[19] and are classified as a "known human carcinogen" by the International Agency for Research on Cancer (IARC).

[12][22] Among these diesel emission components, particulate matter has been a serious concern for human health due to its direct and broad impact on the respiratory organs.

[1] Long-term exposure to urban air pollution containing soot increases the risk of coronary artery disease.

[23] Diesel exhaust (DE) gas is a major contributor to combustion-derived particulate-matter air pollution.

[12] In human experimental studies using an exposure chamber setup, DE has been linked to acute vascular dysfunction and increased thrombus formation.

[24][25] This serves as a plausible mechanistic link between the previously described association between particulate matter air pollution and increased cardiovascular morbidity and mortality.

Empirical models are easy to implement and provide excellent correlations for a given set of operating conditions.

Semi-empirical models reduce computational costs primarily by simplifying the chemistry in soot formation and oxidation.

[1] Historically soot was used in manufacturing artistic paints and shoe polish, as well as a blackener for Russia leather for boots.