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Volatile Organic Compounds

What are Volatile Organic Compounds?

Actually, no widely supported definition of a VOC exists. The definitions of VOCs used for control of the causes of photochemical smog used by EPA and states for their outdoor air pollution regulations includes exemptions for compounds that are technically only those volatile organic compounds but that are determined to be non-reactive or of low-reactivity in the smog formation process.

The EPA formerly defined these compounds as Reactive Organic Gases (ROG) but changed the terminology to VOC for simplicity’s sake. However, this specific use of the term VOCs can be misleading, specifically when applied to indoor air quality because many chemicals that are not regulated for purposes of controlling outdoor air pollution, but are important from an indoor air quality perspective are still found in products that are labeled as to VOC content according to the requirements of ambient air pollution regulations.

Government Regulations

VOCs (or specific subsets of the VOCs) are legally defined in the various laws and codes under which they are regulated. Other definitions may be found from government agencies investigating or advising about VOCs. For Instance:

  • The United States Environmental Protection Agency regulates VOCs in the air, water, and land. The Safe Drinking Water Act implementation even includes a short list labeled VOCs in connection with contaminants which are organic and volatile.
  • The EPA also publishes testing methods for chemical compounds, some of which refer to VOCs.
    In addition to drinking water, VOCs are regulated in discharges to waters (sewage treatment and stormwater disposal), as hazardous waste, but not in non industrial indoor air.
  • In addition to drinking water, VOCs are regulated in discharges to waters (sewage treatment and stormwater disposal), as hazardous waste, but not in non industrial indoor air.
    The United States Department of Labor and its Occupational Safety and Health Administration (OSHA) regulate VOC exposure in the workplace.
  • Volatile organic compounds which are hazardous material would be regulated by the Pipeline and Hazardous Materials Safety Administration while being transported.

Major Sources

Paints and coatings

A major source of man-made VOCs are solvents, especially paints and protective coatings. Solvents are required to spread a protective or decorative film. Approximately 12 billion liters of paints are produced annually. Typical solvents are aliphatic hydrocarbons, ethyl acetate, glycol ethers, and acetone. Motivated by cost, environmental concerns, and regulation, the paint and coating industries are increasingly shifting toward aqueous solvents.

Chlorofluorocarbons and chlorocarbons

Chlorofluorocarbons, which are banned or highly regulated, were widely used cleaning products and refrigerants. Tetrachloroethene is used widely in dry cleaning and by industry. Industrial use of fossil fuels produces VOCs either directly as products (e.g. gasoline) or indirectly as byproducts (e.g. automobile exhaust).


Many building materials such as paints, adhesives, wall boards, and ceiling tiles slowly emit formaldehyde, which irritates the mucous membranes and can make a person irritated and uncomfortable. Formaldehyde emissions from wood are in the range of 0.02 – 0.04 ppm. Relative humidity within an indoor environment can also affect the emissions of formaldehyde. High relative humidity and high temperatures allow more vaporization of formaldehyde from wood-materials. There are also many sources of VOCs in office buildings, which include new furnishings, wall coverings, and office equipment such as photocopy machines which can off-gas VOCs into the air.