Volatile organic compounds (VOCs) are broadly defined as chemical compounds based on carbon chains or rings with vapor pressures greater than 0.1 millimeters of mercury at room temperature. These compounds typically contain hydrogen and may contain oxygen, nitrogen and other elements. Carbon monoxide, carbon dioxide, carbonic acid, metallic carbides and carbonate salts are excluded. Methane also is often excluded from the definition.

There are many potential indoor sources of exposure to airborne VOCs. These sources include many classes of consumer products used for personal care, cleaning, deodorizing, pest management, building maintenance and office work. Many of the materials that are used to finish interiors of buildings emit VOCs to air when they are new. These include all of the common materials such as composite wood products used in cabinetry, carpets and carpet cushions, resilient flooring, and architectural finishes for walls, ceilings, and woodwork. Attached garages in houses and other buildings are a potential source of fuel and vehicle related emissions. Not surprisingly, a large fraction of the population is exposed in various indoor environments to environmental tobacco smoke (ETS), which contains numerous vapor-phase organic compounds.

Since there are so many potential indoor sources of VOCs, people are routinely exposed via the inhalation pathway to complex mixtures of compounds at home, school, work and other indoor environments. Not much is known about the potential effects of these mixtures. However, individually, many of the compounds comprising these mixtures are considered to be harmful to human health and comfort at some level. Federal and state regulatory programs aimed at the control of ambient outdoor air exposures to airborne contaminants, limit industrial emissions to the atmosphere of chemicals that may cause cancer or reproductive harm. In the indoor environment, there are additional health and comfort concerns related to chemical exposures. Many of the carcinogens and reproductive toxins (as well as other chemicals) may have acute and chronic systemic effects. A large number of chemicals are used industrially, and a substantial body of information has been developed regarding their effects on workers. Guideline concentrations have been developed for industrial chemicals to protect workers from acute and chronic toxicity. The potential of many of these chemicals to produce sensory irritancy (i.e., irritation of the eyes and upper respiratory tract) serves as the basis for more than one-half of the workplace guideline concentrations. Objectionable odors generated by certain airborne chemicals, although not always indicative of potential harm, adversely affect people's satisfaction with indoor air quality and frequently lead to complaints.

Additional sources of information on the health effects of VOCs.