Volatile organic compound
- Abbreviation
- VOC
- Also known as
- VOCs, VOC content, low-VOC
A volatile organic compound (VOC) is a carbon-based chemical that evaporates readily at room temperature. In U.S. air quality regulation, VOCs are those that take part in the reactions forming ground-level ozone, which is why coatings, cleaners and other products face VOC limits.
What is a volatile organic compound?
Volatile organic compounds are carbon-containing chemicals that evaporate easily at ordinary temperatures. Solvents in paints, cleaners, adhesives and fuels are common sources. The term has a general meaning and a specific regulatory one.
For air quality regulation, the U.S. Environmental Protection Agency defines a VOC as any compound of carbon, other than carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, that participates in atmospheric photochemical reactions. EPA exempts a list of compounds judged to have negligible photochemical reactivity, such as acetone.
Why VOCs are regulated
In sunlight, VOCs react with nitrogen oxides in the air to form ground-level ozone, a main component of smog that harms human health and vegetation. Some VOCs are also toxic in their own right, and VOCs contribute to indoor air pollution. Limiting VOC emissions is therefore a central part of air quality programs.
VOC limits on products
- Architectural coatings. EPA sets national VOC content limits for paints and coatings, and some states and air districts, notably in California, set stricter limits.
- Consumer and commercial products. Cleaning products, aerosols and other consumer products are subject to VOC limits in many states.
- Industrial operations. Facilities that use solvents and coatings are regulated on their emissions.
Limits are usually expressed as grams of VOC per liter of product, measured by specified test methods.
Formulating with fewer VOCs
Reducing VOCs means replacing volatile solvents with water or low-volatility alternatives, which changes how a product wets, levels and dries. In waterborne coatings, for example, formulators rely on surfactants for wetting and pigment dispersion, and on coalescing agents chosen for low volatility, to maintain performance.
Frequently asked questions
It means a product’s VOC content is below a stated threshold, often a regulatory limit for its category or a lower level set by a certification program. Definitions vary, so the specific limit and test method matter.
Not in the regulatory sense. EPA’s definition excludes certain carbon compounds and exempts others with negligible reactivity, so some volatile solvents are not counted as VOCs for regulatory purposes.
Sources
- Definition of volatile organic compounds, 40 CFR 51.100(s), U.S. Environmental Protection Agency
- National Volatile Organic Compound Emission Standards for Architectural Coatings, 40 CFR Part 59 Subpart D, U.S. Environmental Protection Agency