Volatile Organic Compound

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.Volatile organic compounds (VOCs) are organic  chemical compounds that have high enough vapour pressures under normal conditions to significantly vaporize and enter the atmosphere. 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).
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Any organic compound that participates in atmospheric photochemical reactions except those designated by EPA as having negligible photochemical reactivity.