Volatile organic compounds (VOCs) are organic chemical compounds that have high enough vapour pressures under normal conditions to significantly vaporize and enter the atmosphere. (The term VOC is also occasionally used as an abbreviation, especially in biological contexts, for "volatile organic carbon".) A wide range of carbon-based molecules, such as aldehydes, ketones, and hydrocarbons are VOC's. 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. Others believe the concept that a volatile organic compound is any organic that participates in a photoreaction, as found in the EPA's definition, is very broad and vague. Organics that are not volatile, as described above, can fall into that definition. The term may refer both to well characterized organic compounds and to mixtures of variable composition. Most often the definition used is one from the United States Environmental Protection Agency (see below). A chemical substance is any material substance used in or obtained by a process in chemistry: A chemical compound is a substance consisting of two or more chemical elements that are chemically combined in fixed proportions. ... The vapor pressure is the pressure (if the vapor is mixed with other gases, the partial pressure) of a vapor. ... An aldehyde. ... Ketone group A ketone(key tone) is either the functional group characterized by a carbonyl group (O=C) linked to two other carbon atoms or a chemical compound that contains this functional group. ... Oil refineries are key to obtaining hydrocarbons; crude oil is processed through several stages to form desirable hydrocarbons, used in fuel and other commercial products. ...

Sources of VOCs

Common artificial sources of VOCs include paint thinners, dry cleaning solvents, and some constituents of petroleum fuels (eg. gasoline and natural gas). Trees are also an important biological source of VOC. It is also known that trees emit large amounts of VOCs especially isoprene and terpenes. Significant biological sources of methane are termites, cows (ruminants) and cultivation (estimated emissions 15, 75 and 100 million tons per year respectively). Turpentine substitute is a mineral based replacement for the vegetable based organic solvent turpentine. ... Dry cleaning is any cleaning process for clothing and textiles using an organic solvent other than water. ... A solvent is a liquid that dissolves a solid, liquid, or gaseous solute, resulting in a solution. ... Pumpjack pumping an oil well near Lubbock, Texas Ignacy Łukasiewicz - inventor of the refining of kerosene from crude oil. ... Gasoline or petrol is a petroleum-derived liquid mixture consisting mostly of hydrocarbons and enhanced with benzene or iso-octane to increase octane ratings, used as fuel in internal combustion engines. ... The coniferous Coast Redwood, the tallest tree species on earth. ... Isoprene is a common synonym for the chemical compound 2-methyl-1,3-butadiene. ... Terpenes are a class of hydrocarbons, produced by many plants, particularly conifers. ...

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 both VOC handling on newer tankers and also crude oil loading terminals.

Also many VOCs are found in brownfield sites. In town planning, brownfield land is an area of land previously used or built upon, as opposed to industry or mining and therefore may be contaminated by hazardous waste or pollution. ...

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Environmental Effects

VOCs are sometimes accidentally released into the environment, where they can damage soil and groundwater contaminants. Vapours of VOCs escaping into the air contribute to air pollution. Loess field in Germany Surface-water-gley developed in glacial till, Northern Ireland Soil comprising the pedosphere is positioned at the interface of the lithosphere and biosphere with the atmosphere and hydrosphere. ... Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of geologic formations. ... The Lachine Canal, in Montreal, is badly polluted Pollution is the release of harmful environmental contaminants, or the substances so released. ... Air pollution is a chemical, physical (e. ...

VOCs are an important outdoor air pollutant. In this field they are often divided up into the separate categories of methane (CH₄) 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 carcinogens and may lead to leukaemia through prolonged exposure. 1,3-butadiene is another dangerous compound which is often associated with industrial uses. Methane is a chemical compound with the molecular formula CH4. ... Top: Increasing atmospheric CO2 levels as measured in the atmosphere and ice cores. ... Global mean surface temperatures 1850 to 2006 Mean surface temperature anomalies during the period 1995 to 2004 with respect to the average temperatures from 1940 to 1980 Global warming is the observed increase in the average temperature of the Earths atmosphere and oceans in recent decades and the projected... Benzene, also known as benzol, is an organic chemical compound with the formula C6H6. ... Toluene, also known as methylbenzene or phenylmethane is a clear, water-insoluble liquid with the typical smell of paint thinners, redolent of the sweet smell of the related compound benzene. ... The term xylenes refers to a group of 3 benzene derivatives which encompasses ortho-, meta-, and para- isomers of dimethyl benzene. ... The term carcinogen refers to any substance, radionuclide or radiation which is an agent directly involved in the promotion of cancer or in the facilitation of its propagation. ... Leukemia (leukaemia in Commonwealth English) is a group of blood diseases characterized by malignancies (cancer) of the blood-forming tissues. ... Butadiene can refer to either one of two hydrocarbon chemical compounds which are alkenes that are isomers of each other. ...

Some VOCs also react with nitrogen oxides 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 respiratory problems. In addition high concentrations of low level ozone can damage crops and buildings. The term nitrogen oxide is a general term and can be used to refer to any of these oxides (oxygen compounds) of nitrogen, or to a mixture of them: Nitric oxide (NO), nitrogen(II) oxide Nitrogen dioxide (NO2) Dinitrogen monoxide (N2O) (Nitrous oxide) Dinitrogen trioxide (N2O3) Dinitrogen tetroxide (N2O4) Dinitrogen... For other uses, see Ozone (disambiguation). ... Solar irradiance spectrum at top of atmosphere. ... // In animal physiology, respiration is the transport of oxygen from the ambient air to the tissue cells and the transport of carbon dioxide in the opposite direction. ...

Contribution to Indoor Air Pollution

Many VOCs found around the house, such as paint strippers and wood preservatives, 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. Trunks A tree trunk as found at the Veluwe, The Netherlands Wood is a solid material derived from woody plants, notably trees but also shrubs. ... A preservative is a natural or synthetic chemical that is added to products such as foods, pharmaceuticals, paints, biological samples, etc. ... Sick building syndrome (SBS) is a combination of ailments (a syndrome) associated with an individuals place of work (typically, but not always, an office building), though there have also been instances of SBS in residential buildings. ... EPA redirects here. ...

Air quality with reference to Volatile Organic Compund Emission.

Terminology and legal definitions

There are a number of different ways to collectively refer to those chemical compounds that participate in photochemical reactions. That is, those that react with other pollutants, in the presence of sunlight, to form tropospheric ozone. A photochemical reaction is a chemical reaction which is induced by light. ... Ozone (O3) is a key constituent of the troposphere. ...

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
• 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. The European Parliament is the directly elected parliamentary body of the European Union. ...

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. Look up policy in Wiktionary, the free dictionary. ... The Code of Federal Regulations (CFR) is the codification of the general and permanent rules and regulations (sometimes called administrative law) published in the Federal Register by the executive departments and agencies of the Federal Government of the United States. ... For the album by Ash, see 1977 (album). ...

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. (See Maximum Incremental Reactivity, MIR [1].)

US EPA CFR Definition

40 CFR Part 51.100(s) gives this definition as follows:

Volatile organic compounds (VOC) means any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photochemical reactions.

(1) This includes any such organic compound other than the following, which have been determined to have negligible photochemical reactivity: methane; ethane; methylene chloride (dichloromethane); 1,1,1-trichloroethane (methyl chloroform); 1,1,2-trichloro-1,2,2-trifluoroethane (CFC–113); trichlorofluoromethane (CFC–11); dichlorodifluoromethane (CFC–12); chlorodifluoromethane (HCFC–22); trifluoromethane (HFC–23); 1,2-dichloro-1,1,2,2-tetrafluoroethane (CFC–114); chloropentafluoroethane (CFC–115); 1,1,1-trifluoro-2,2-dichloroethane (HCFC–123); 1,1,1,2-tetrafluoroethane (HFC–134a); 1,1-dichloro-1-fluoroethane (HCFC–141b); 1-chloro-1,1-difluoroethane (HCFC–142b); 2-chloro-1,1,1,2-tetrafluoroethane (HCFC–124); pentafluoroethane (HFC–125); 1,1,2,2-tetrafluoroethane (HFC–134); 1,1,1-trifluoroethane (HFC–143a); 1,1-difluoroethane (HFC–152a); parachlorobenzotrifluoride (PCBTF); cyclic, branched, or linear completely methylated siloxanes; acetone; perchloroethylene (tetrachloroethylene); 3,3-dichloro-1,1,1,2,2-pentafluoropropane (HCFC–225ca); 1,3-dichloro-1,1,2,2,3-pentafluoropropane (HCFC–225cb); 1,1,1,2,3,4,4,5,5,5-decafluoropentane (HFC 43–10mee); difluoromethane (HFC–32); ethylfluoride (HFC–161); 1,1,1,3,3,3-hexafluoropropane (HFC–236fa); 1,1,2,2,3-pentafluoropropane (HFC–245ca); 1,1,2,3,3-pentafluoropropane (HFC–245ea); 1,1,1,2,3-pentafluoropropane (HFC–245eb); 1,1,1,3,3-pentafluoropropane (HFC–245fa); 1,1,1,2,3,3-hexafluoropropane (HFC–236ea); 1,1,1,3,3-pentafluorobutane (HFC–365mfc); chlorofluoromethane (HCFC–31); 1- chloro-1-fluoroethane (HCFC–151a); 1,2-dichloro-1,1,2-trifluoroethane (HCFC–123a); 1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxy-butane (C₄F₉OCH₃ or HFE-7100); 2-(difluoromethoxymethyl)-1,1,1,2,3,3,3-heptafluoropropane ((CF₃)₂CFCF₂OCH₃); 1-ethoxy-1,1,2,2,3,3,4,4,4-nonafluorobutane (C₄F₉OC₂H₅ or HFE-7200); 2-(ethoxydifluoromethyl)-1,1,1,2,3,3,3-heptafluoropropane ((CF₃)₂CFCF₂OC₂H₅); methyl acetate; 1,1,1,2,2,3,3-heptafluoro-3-methoxy-propane (n-C₃F₇OCH₃ or HFE–7000); 3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-(trifluoromethyl) hexane (HFE–7500); 1,1,1,2,3,3,3-heptafluoropropane (HFC 227ea); methyl formate (HCOOCH₃); and perfluorocarbon compounds which fall into these classes:

(i) Cyclic, branched, or linear, completely fluorinated alkanes;

(ii) Cyclic, branched, or linear, completely fluorinated ethers with no unsaturations;

(iii) Cyclic, branched, or linear, completely fluorinated tertiary amines with no unsaturations; and

(iv) Sulfur containing perfluorocarbons with no unsaturations and with sulfur bonds only to carbon and fluorine.

Refer to the current CFR for up-to-date definition [2]. Methane is a chemical compound with the molecular formula CH4. ... Ethane is a chemical compound with chemical formula C2H6. ... Dichloromethane or Methylene chloride is a chemical compound widely used as a solvent for organic materials. ... The chemical compound 1,1,1-trichloroethane is a chlorinated hydrocarbon that was until recently widely used as an industrial solvent. ... R-11, or trichlorofluoromethane, was the first widely used refrigerant. ... Disclaimer and references Dichlorodifluoromethane (R-12), usually sold under the brand name Freon-12, is a chlorofluorocarbon halomethane used as a refrigerant and aerosol spray propellant until its manufacture was discontinued in 1995, due to concerns about damage to the ozone layer. ... Cl | F--C--F | H Chlorodifluoromethane or difluoromonochloromethane is a hydrochlorofluorocarbon (HCFC) with chemical formula CHClF2 and CAS number 75-45-6. ... Trifluoromethane (CHF3), also known as fluoroform, is one of the haloalkanes with zero ozone depletion, as it does not contain any chlorine. ... 1,2-Dichlorotetrafluoroethane, or R-114, is a chlorofluorocarbon (CFC) with the molecular formula ClF2CCF2Cl. ... 2,2-Dichloro-1,1,1-trifluoroethane or HCFC-123 is primarily considered as an alternative to CFC-11 in refrigeration systems, although it may have limited application in firefighting, foam blowing processes, and solvent applications. ... 1,1,1,2-Tetrafluoroethane, also called simply tetrafluoroethane, R-134a or HFC-134a, is a refrigerant without an ozone depletion potential and thermodynamic properties similar to R-12 (dichlorodifluoromethane). ... 1,1,2,2,2-Pentafluoroethane, also called simply pentafluoroethane or R-125, is a refrigerant that has zero ozone depletion potential. ... 1,1,1-Trifluoroethane, or R-143a or simply trifluoroethane, is an fluorocarbon compound that is a clear, colorless gas. ... This article or section does not adequately cite its references or sources. ... Siloxanes are a class of both organic and inorganic chemical compounds which consist entirely of silicon, oxygen, and an alkyl group. ... In chemistry, acetone (also known as propanone, dimethyl ketone, 2-propanone, propan-2-one and β-ketopropane) is the simplest representative of the ketones. ... Tetrachloroethylene Cl2C=CCl2 is a manufactured chemical compound that is widely used for the dry cleaning of fabrics and for metal-degreasing. ... Difluoromethane is an organic compound of the di-halogenoalkane variety. ... Chlorofluoromethane or Freon 31 is a mixed halomethane (fluorochlorocarbon - FCC). ... Methyl acetate, also known as acetic acid methyl ester or methyl ethanoate, is a clear, flammable liquid with a characteristic, not unpleasant smell like certain glues or nail polish removers. ... 1,1,1,2,3,3,3-Heptafluoropropane, also called heptafluoropropane, HFC-227 or HFC-227ea (ISO name), is a colourless odourless gaseous halocarbon. ... Methyl formate, also called methyl methanoate, is the methyl ester of formic acid. ... Perfluorocarbons (PFCs) are compounds derived from hydrocarbons by replacement of hydrogen atoms by fluorine atoms. ... Chemical structure of methane, the simplest alkane Alkanes are chemical compounds that consists only of the elements carbon (C) and hydrogen (H) (i. ... Ether is the general name for a class of chemical compounds which contain an ether group — an oxygen atom connected to two (substituted) alkyl groups. ... The general structure of an amine Amines are organic compounds and a type of functional group that contain nitrogen as the key atom. ...

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. 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. A directive is a legislative act of the European Union which requires member states to achieve a particular result without dictating the means of achieving that result. ...

Classification in the UK

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. Information is provided according to 5 ‘bands’ and manufacturers have a choice of label design to use, either a British Coatings Federation text box on the back panel or a globe label, the latter subject to signing a licence agreement with B&Q plc.

The five bands are:

Minimal - VOC content 0% to 0.29%
Low - VOC content 0.3% to 7.99%
Medium - VOC content 8% to 24.99%
High - VOC content 25% to 50%
Very High - VOC content more than 50%

An example of text box labelling for the Minimal band is shown below.

For the globe symbols, see [3] Image File history File links No higher resolution available. ...

Other relevance

Some types of VOC (phytoncides) are used in aromatherapy and holistic medicine and are a factor in locating some sanitoriums and health farms and in oak or pine forests. Phytoncide - native volatile organic substances which is contained in plants scents. ... Sanatório Heliantia A sanatorium refers to a medical facility for long-term illness, typically cholera or tuberculosis. ...

See also

• Volatility (physics)
• Solvent
• Dutch standards
• Organic compound
• Photochemical smog
• Criteria air contaminants

Volatility in physics is a measure of the speed at which a chemical element or chemical compound evaporates. ... A solvent is a liquid that dissolves a solid, liquid, or gaseous solute, resulting in a solution. ... Dutch Standard reference values for environmental investigation, clean up and remediation. ... Benzene is the simplest of the arenes, a family of organic compounds An organic compound is any member of a large class of chemical compounds whose molecules contain carbon and hydrogen; therefore, carbides, carbonates, carbon oxides and elementary carbon are not organic (see below for more on the definition controversy... Photochemical smog is the term to represent a multitude of chemical agents which are considered to be detrimental to the environment and health. ... Criteria air contaminants (CAC) are a group of air pollutants that cause smog, acid rain and other health hazards. ...

External links

• Sources of Indoor Air Pollution
• EPA NE: Ground-level Ozone (Smog) Information
• VOC emission from crude oil tankers
• VOC reduction technology
• VOC reduction technology