Editing Soot (section)

== Sources ==
Soot as an airborne contaminant in the environment has many different sources, all of which are results of some form of [[pyrolysis]]. They include soot from [[coal]] burning, internal-combustion engines,<ref name="modeling"/> power-plant boilers, hog-fuel boilers, ship boilers, central steam-heat boilers, [[waste incineration]], local field burning, house fires, forest fires, fireplaces, and furnaces. These exterior sources also contribute to the indoor environment sources such as smoking of plant matter, cooking, [[oil lamp]]s, [[candle]]s, quartz/halogen bulbs with settled dust, [[fireplace]]s, exhaust emissions from vehicles,<ref name="b20">{{cite journal|last1=Omidvarborna|title=Characterization of particulate matter emitted from transit buses fueled with B20 in idle modes|journal=Journal of Environmental Chemical Engineering|volume=2|issue=4|pages=2335–2342|doi=10.1016/j.jece.2014.09.020|display-authors=etal|year=2014}}</ref> and defective furnaces. Soot in very low concentrations is capable of darkening surfaces or making particle agglomerates, such as those from ventilation systems, appear [[black carbon|black]]. Soot is the primary cause of "ghosting", the discoloration of walls and ceilings or walls and flooring where they meet. It is generally responsible for the discoloration of the walls above baseboard [[electric heating]] units.

The formation and properties of soot depend strongly on the fuel composition, but may also be influenced by flame temperature.<ref>{{cite book |last1=Seinfeld |first1=John H. |last2=Pandis |first2=Spyros N. |title=Atmospheric Chemistry and Physics : From Air Pollution to Climate Change |edition=2nd |publisher=John Wiley & Sons |year=2006 |isbn=0-471-72018-6 }}</ref><ref>{{Cite journal |last1=Alfè |first1=M. |last2=Apicella |first2=B. |last3=Rouzaud |first3=J.-N. |last4=Tregrossi |first4=A. |last5=Ciajolo |first5=A. |date=October 2010 |title=The effect of temperature on soot properties in premixed methane flames |url=https://linkinghub.elsevier.com/retrieve/pii/S0010218010000374 |journal=Combustion and Flame |language=en |volume=157 |issue=10 |pages=1959–1965 |doi=10.1016/j.combustflame.2010.02.007|bibcode=2010CoFl..157.1959A }}</ref> Regarding fuel composition, the rank ordering of sooting tendency of fuel components is:{{clarify|date=September 2024}} [[naphthalenes]] → [[benzenes]] → [[aliphatics]].{{citation needed|date=September 2024}} However, the order of sooting tendencies of the aliphatics ([[alkanes]], [[alkenes]], and [[alkynes]]) varies dramatically depending on the flame type. The difference between the sooting tendencies of aliphatics and aromatics is thought to result mainly from the different routes of formation. Aliphatics appear to first form acetylene and polyacetylenes, which is a slow process; aromatics can form soot both by this route and also by a more direct pathway involving ring condensation or polymerization reactions building on the existing aromatic structure.<ref>{{cite journal |last1=Graham |first1=S. C. |last2=Homer |first2=J. B. |last3=Rosenfeld |first3=J. L. J. |year=1975 |jstor=78961 |title=The formation and coagulation of soot aerosols generated in pyrolysis of aromatic hydrocarbons |journal=Proc. R. Soc. Lond. A |volume=344 |pages=259–285 |doi=10.1098/rspa.1975.0101 |s2cid=96742040 }}</ref><ref>{{cite book |last1=Flagan |first1=R. C. |last2=Seinfeld |first2=J. H. |year=1988 |title=Fundamentals of Air Pollution Engineering |publisher=Prentice-Hall |location=Englewood Cliffs, NJ |isbn=0-13-332537-7 }}</ref>