Volatile organic compound 1014518 218182797 2008-06-09T14:53:48Z Swatjester 751903 rvv <div class="messagebox cleanup metadata">This article describes a '''highly specialized''' aspect of its subject in the "Terminology and legal definitions" section. Please help Wikipedia by adding more general information.</div> {{Refimprove|date=September 2007}} {{redirect|ROG}} '''Volatile organic compounds''' ('''VOCs''') are organic [[chemical]] compounds that have high enough [[vapor pressure]]s under normal conditions to significantly [[vaporize]] and enter the atmosphere. A wide range of carbon-based molecules, such as [[aldehyde]]s, [[ketone]]s, and other light [[hydrocarbon]]s are VOCs. The term often is used in a legal or regulatory context and in such cases the precise definition is a matter of law. These definitions can be contradictory and may contain "loopholes"; e.g. exceptions, exemptions, and exclusions. The [[United States Environmental Protection Agency]] defines a VOC as any organic compound that participates in a photoreaction; others believe this definition is very broad and vague <!--Who makes this criticism? - RWS --> as organics that are not volatile in the sense that they vaporize under normal conditions can be considered volatile by this EPA definition. The term may refer both to well characterized organic compounds and to [[mixture]]s of variable composition. ==Sources of VOCs== The most common VOC is [[methane]], a [[greenhouse gas]] sometimes excluded from analysis of other VOCs using the term non-methane VOCs, or NMVOCs.<ref>[http://www.atmosphere.mpg.de/enid/3rr.html "ESPERE Climate Encyclopedia."] (Website.) Atmospheric Chemistry Department, Max Planck Institute for Chemistry. "Industry" section. Retrieved on [[2007]]-[[09-26]].</ref> Other terms used in pollution regulations include NMOG - "non-methane organic gas", and NMHC - "non-methane hydrocarbons".<ref>[http://www.epa.gov/greenvehicles/Aboutratings.do#aboutairpollution About EPA's Ratings]</ref> <!-- These terms redirect to this article. --> Major worldwide sources of atmospheric methane include [[wetlands]], [[ruminants]] such as cows, energy use, [[rice]] agriculture, [[landfill]]s, and burning biomass such as wood.<ref>[http://www.grida.no/climate/ipcc_tar/wg1/134.htm#4211 "Climate Change 2001: The Scientific Basis"] [[Intergovernmental Panel on Climate Change]] (IPCC), published on United Nations Environmental Programme/GRID-Arendale website. Section 4.2.1.1: "Non-CO2 Kyoto Gases, Methane (CH<sub>4</sub>)." Retrieved on [[2007]]-[[09-26]].</ref> Methane is the primary component of [[natural gas]].<ref> {{cite web | url = http://www.naturalgas.org/overview/background.asp | title = Background | accessdate = 2008-01-06 }}</ref> Common artificial VOCs include [[paint thinner]]s, [[dry cleaning]] [[solvent]]s, and some constituents of [[petroleum]] fuels (eg. [[gasoline]] and [[natural gas]]). [[Tree]]s are also an important biological source of VOC; it is known that they emit large amounts of VOCs, especially [[isoprene]] and [[terpenes]]. Another significant source of VOC emission is crude oil tanking. Both during offloading and loading of crude oil tankers VOC are released to the atmosphere. Lately, there has been an environmental focus on this issue resulting in improved VOC handling on newer tankers, and crude oil loading terminals. Considered a factor in indoor air quality issues such as [[sick building syndrome]], VOCs "are generated by photocopiers, carpets, and furnishings as they are used or when components oxidize.... One irritant, [[formaldehyde]], present in hundreds of office components, including wood and laminated furniture, shelving, and wall covers. It also evaporates from paints, varnishes, and chemicals used for sealing and finishing walls."<ref>[[2007]]-[[05-02]]. [http://www.medical-library.org/journals3a/sick_building_syndrome.htm "Sick Building Syndrome - New Treatments, May 2, 2007"] (Website). Library of the National Medical Society. Retrieved on [[2007]]-[[09-03]].</ref> Tobacco smoke can contribute high levels of VOCs.<ref>[http://www.epa.gov/iaq/pubs/sbs.html "Indoor Air Facts No. 4 (revised) Sick Building Syndrome."] (Website). U.S. Environmental Protection Agency. Retrieved on [[2007]]-[[09-03]].</ref> VOCs including halogenide and sulfide are emitted through human respiration<ref>Hajima, Tamura, Yoneda Shuji, Fujii Shuji, Yuasa Kazuhiro, Suzuki Miyako. 1999. [http://sciencelinks.jp/j-east/article/199919/000019991999A0662886.php "Measurement of volatile organic compounds generated from human being."] ''Kuki Seijo to Kontamineshyon Kontororu Kenkyu Taikai Yokoshu'', vol. 17, pp. 131-132 (Japanese), via English-language abstract on sciencelinks.jp. Retrieved on [[2007]]-[[09-03]].</ref>, and formaldehyde is emitted at a lower rate from the surface of the human body{{Verify source|date=May 2008}}.<ref>Hajima, Tamura, Yoneda Shuji, Fujii Shuji, Yuasa Kazuhiro, Suzuki Miyako. 1999. [http://sciencelinks.jp/j-east/article/199919/000019991999A0662886.php "Measurement of volatile organic compounds generated from human being."] ''Kuki Seijo to Kontamineshyon Kontororu Kenkyu Taikai Yokoshu'', vol. 17, pp. 131-132 (Japanese), via English-language abstract on sciencelinks.jp. Retrieved on [[2007]]-[[09-03]].</ref> Also many VOCs are found in [[brownfield_land|brownfield]] sites.<ref>[http://www.epa.gov/swerosps/bf/html-doc/danbury2.htm "Brownfields Assessment Pilot Fact Sheet"] (Website.) US Environmental Protection Agency Retrieved on [[2000]]-[[12]].</ref> ==Environmental effects== VOCs are sometimes accidentally released into [[the environment]], where they can damage [[soil]] and [[groundwater]]. Vapours of VOCs escaping into the air contribute to [[air pollution]]. VOCs are an important outdoor air pollutant. In this field they are often divided into the separate categories of [[methane]] ((CH<sub>4</sub>) and non-methane (NMVOCs). Methane is an extremely efficient [[greenhouse gas]] which contributes to enhanced [[global warming]]. Other hydrocarbon VOCs are also significant greenhouse gases via their role in creating ozone and in prolonging the life of methane in the atmosphere, although the effect varies depending on local air quality. Within the NMVOCs, the aromatic compounds [[benzene]], [[toluene]] and [[xylene]] are suspected [[carcinogen]]s and may lead to [[leukemia]] through prolonged exposure. 1,3-[[butadiene]] is another dangerous compound which is often associated with industrial uses. Some VOCs also react with [[nitrogen oxide]]s in the air in the presence of sunlight to form [[ozone]]. Although ozone is beneficial in the upper atmosphere because it absorbs UV thus protecting humans, plants, and animals from exposure to dangerous [[solar radiation]], it poses a health threat in the lower atmosphere by causing [[respiration (physiology)|respiratory]] problems. In addition high concentrations of low level ozone can damage crops and buildings. ==Contribution to indoor air pollution== Many VOCs found around the house, such as paint strippers and [[wood]] [[preservative]]s, contribute to [[sick building syndrome]] because of their high vapour pressure. VOC's are often used in paint, carpet backing, plastics, and cosmetics. The [[United States Environmental Protection Agency]] (EPA) has found concentrations of VOCs in indoor air to be 2 to 5 times greater than in outdoor air. During certain activities indoor levels of VOCs may reach 1,000 times that of the outside air. Not all organic compounds are volatile; many plastics (polymers) and other large molecules may not have significant vapor pressure at normal temperatures. Air quality with reference to Volatile Organic Compound Emission. ==Terminology and legal definitions== There are a number of different ways to collectively refer to those chemical compounds that participate in [[photochemical reaction]]s. That is, those that react with other pollutants, in the presence of sunlight, to form [[tropospheric ozone]]. Some of the more common terms are: *'''NMHC''' — Non-Methane Hydrocarbons *'''NMOG''' — Non-Methane Organic Gases *'''NMVOC''' — Non-Methane Volatile Organic Compounds *'''ROG''' — Reactive Organic Gases *'''SVOC''' — Semi-Volatile Organic Compounds *'''TOG''' — Total Organic Gases *'''TVOC''' — Total Volatile Organic Compounds *'''VOC''' — Volatile Organic Compounds While all these terms are used, it is not always clear which pollutants are included in each term. The term "VOC" has the advantage of having precise definitions codified by regulators such as the [[European Parliament]] and the US EPA. Worldwide, legal definitions of the term "VOC" are in many respects, more a matter of [[policy]] than a matter of science. For example, because the US EPA [[Code of Federal Regulations]] (CFR) has characterized a compound as having "negligible photochemical reactivity" it does not necessarily imply that it is, at any particular time, less reactive than those compounds which are not on the list. Since first establishing the list of exempt compounds in [[1977]], the EPA has added several to the list, and frequently has several petitions undergoing review. The traditional US standard to determine if a compound is a non-VOC is to compare its reactivity to that of ethane, which was the least reactive compound on the original list. Unfortunately, this is a very difficult comparison to make as it is frequently impossible to duplicate the real-world conditions in a laboratory. To complicate the issue, typical real-world conditions are different from day to day and from place to place. However, there is ongoing study on the use of a compound's reactivity as a better tool for pollution control regulation than the "is or isn't" approach currently in use.<ref>[http://www.arb.ca.gov/research/reactivity/history.htm Air Resources Board: Reactivity Background] (Website). Air Resources Board, California Environmental Protection Agency. Retrieved on [[2007]]-[[09-03]].</ref> ===United States definition=== The [[United States Environmental Protection Agency|U.S. Environmental Protection Agency]] definition of VOCs is published in the [[Code of Federal Regulations]]. It defines VOCs as "any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photochemical reactions," but also includes a list of dozens of exceptions for compounds "determined to have negligible photochemical reactivity."<ref>[[2007]]-[[08-30]]. [http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&rgn=div8&view=text&node=40:2.0.1.1.2.3.8.1&idno=40 "Title 40: Protection of Environment, Part 51-Requirements for Preparation, Adoption, and Submittal of Implementation Plans, Subpart F—Procedural Requirements, 51.100: Definitions."] (Website). ''GPO Access: Electronic Code of Federal Regulations (e-CFR)'', United States Government Printing Office. Retrieved on [[2007]]-[[09-03]].</ref> ===European Union definition=== Under European law, the definition of "VOC" is based on evaporation into the atmosphere, rather than reactivity. For example [[European Union Directive]] 2004/42/CE which covers VOC emissions from paints and varnishes defines a VOC as any organic compound having an initial boiling point less than or equal to 250°C measured at a standard atmospheric pressure of 101.3 kPa.<ref>[http://eur-lex.europa.eu/smartapi/cgi/sga_doc?smartapi!celexapi!prod!CELEXnumdoc&numdoc=32004L0042&model=guichett&lg=en "Directive 2004/42/CE of the European Parliament and of the Council"] (Website.) ''EUR-Lex'', European Union Publications Office. Retrieved on [[2007]]-[[09-27]].</ref> Directive 94/63/EC which regulates VOC emissions from storage and distribution of petrol simply defines ''vapours'' as any gaseous compound which evaporates from petrol.<ref>[http://www.legaltext.ee/text/en/T71047.htm "European Parliament and council directive 94/63/EC of 20 December 1994."] (Website.) Estonian Legal Language Centre, Justiits Ministeerium (Justice Ministry of Estonia). Retrieved on [[2007]]-[[09-27]].</ref> ===UK coatings classification=== The British coatings industry has adopted a VOC labelling scheme for all decorative coatings to inform customers about the levels of organic solvents and other volatile materials present. Coatings manufacturers use standard terminology, text and categories for all products.<ref>[http://www.coatings.org.uk/default.asp?edit_id=299&nav=293&branch=5 "What are VOCs."] (Website). The British Coatings Federation. Retrieved on [[2007]]-[[09-03]].</ref> Information is provided according to five ‘bands,’ and manufacturers may label products with either a British Coatings Federation text box on the back panel, or a graphical globe symbol, the latter subject to licensing from B&Q plc. Both styles of labels contain the same text, and warn that VOCs contribute to atmospheric pollution. The five bands are: Minimal - VOC content 0% to 0.29%<br> Low - VOC content 0.3% to 7.99%<br> Medium - VOC content 8% to 24.99%<br> High - VOC content 25% to 50%<br> Very High - VOC content more than 50% An example of text box labelling for the Minimal band is shown below, while examples of the graphical globe symbols may be seen on websites of some British coatings companies.<ref>[http://www.icipaints.co.uk/support/she/vocs.jsp "VOCs"] (Commercial website). ICI Paints. Retrieved on [[2007]]-[[09-03]].</ref> <center><!-- Deleted image removed: [[Image:Voc textbox.gif]] --></center> ==Notes== {{reflist}} ==See also== * [[Criteria air contaminants]] * [[Dutch standards]] * [[NMVOC]] (non-methane volatile organic compounds) * [[Organic compound]] * [[Photochemical smog]] * [[Solvent]] * [[Volatility (physics)]] ==External links== * [http://www.epa.gov/iaq/voc.html Sources of Indoor Air Pollution] * [http://www.epa.gov/region01/airquality EPA NE: Ground-level Ozone (Smog) Information] * [http://sea.helcom.fi:15037/dps/docs/documents/Maritime%20Group/HELCOM%20MARITIME%204,%202005/6-3.pdf#search=%22VOC%20reduction%20crude%20oil%22 VOC emission from crude oil tankers] * [http://www.sintef.no/content/page1____3567.aspx VOC reduction technology] * [http://www.apl.no/aplweb/templates/Level2Page.aspx?id=467 VOC reduction technology] * [http://www.akerkvaerner.com/Internet/IndustriesAndServices/OilAndGas/Volatile+Organic+CompoundsVOC/default.htm VOC reduction technology] * [http://www.envmodels.com/cov.php VOC emissions and calculations] [[Category:Building biology]] [[Category:Organic compounds]] [[Category:Pollutants]] [[Category:Smog]] [[de:Flüchtige organische Verbindungen]] [[et:Lenduvad orgaanilised ühendid]] [[es:Compuestos orgánicos volátiles]] [[fr:Composé organique volatil]] [[it:Composti organici volatili]] [[nl:Vluchtige organische stof]] [[ja:揮発性有機化合物]] [[pl:Lotne związki organiczne]] [[ru:Летучие органические вещества]] [[fi:VOC-päästöt]] [[sv:Lättflyktiga organiska föreningar]] [[ta:ஆவியாகும் கரிமச் சேர்வை]] [[wuu:挥发性有机化合物]]