Volatile Organic Compounds (VOCs) are carbon-containing chemicals that readily evaporate into gases at room temperatures. They are found extensively in our environment, with concentrations often significantly higher indoors than outdoors. Understanding the origins of VOCs is important for managing indoor air quality.
Building Materials and Furnishings
Many VOCs originate from materials used in constructing and furnishing indoor spaces. Paints, especially solvent-based, varnishes, and sealants commonly contain VOCs like toluene, benzene, and formaldehyde. Adhesives, used in flooring and furniture assembly, also emit VOCs.
Flooring materials, such as vinyl, laminate, and carpets, release VOCs over time. Manufactured wood products like plywood, particleboard, and medium-density fiberboard (MDF) emit formaldehyde due to the resins used in their production. New furniture, made with manufactured wood or certain finishes, also contribute to indoor VOCs.
Off-gassing is the release of chemicals into the air from solids or liquids. This process begins immediately after installation or manufacturing and can continue for days, weeks, or even years, influencing long-term air quality. Carpets, for instance, can off-gas for five years or more.
Household Products and Personal Care Items
Everyday consumer products are another significant source of indoor VOCs. Cleaning supplies, including disinfectants, degreasers, laundry detergents, and air fresheners, contain organic compounds. These products release VOCs through evaporation during use and storage.
Personal care products also contribute to indoor VOCs. Cosmetics, perfumes, hairsprays, and nail polish removers, containing acetone or toluene, emit VOCs during application. Hobby supplies, such as glues, paints, and craft aerosols, also release these compounds.
Some common spray products contain significant concentrations of VOCs like benzene, toluene, and methyl ethyl ketone. Even products marketed as “green” may still emit hazardous VOCs; many compounds are often undisclosed on product labels.
Combustion and Everyday Activities
Combustion processes and routine indoor activities also generate VOCs. Operating gas stoves and ovens, burning candles, and using fireplaces or wood-burning stoves release organic compounds into the air. Tobacco smoke is another source of VOCs, including benzene.
Beyond combustion, activities like dry cleaning can leave residues on clothing that off-gas VOCs, like tetrachloroethylene, after items are brought indoors. Printing with office equipment and engaging in hobbies involving solvents or glues also contribute to indoor VOCs. While intermittent, these sources can lead to temporary increases in indoor VOC levels.
Outdoor and Natural Emissions
VOCs can also originate from sources outside the indoor environment and from natural processes and infiltrate buildings. Vehicle exhaust, from gasoline and diesel combustion, is a major outdoor source in urban areas. Industrial emissions from manufacturing processes, including paints and chemicals, also release these compounds into the atmosphere.
Gasoline vapors from fuel storage and spills contribute to outdoor VOCs. Natural sources also emit VOCs; plants, for instance, release biogenic VOCs like isoprene and terpenes. These outdoor VOCs can enter indoor spaces through open windows, ventilation, or cracks in foundations.