Volatile organic compounds (VOCs) are gases released by thousands of everyday products, from paint and cleaners to new furniture. They're why a freshly painted room smells, and why that smell is worth airing out.
According to the EPA, concentrations of many VOCs are consistently higher indoors than outdoors, up to ten times higher, and activities such as paint stripping can push levels to 1,000 times outdoor background. Ventilation, controlling the source and storing products outside the living space lower them most.
What VOCs are
VOCs are carbon-based chemicals that evaporate at room temperature. Some have strong smells; many have none. Common examples the EPA highlights include methylene chloride in paint strippers, benzene in tobacco smoke and stored fuels, and perchloroethylene from dry-cleaned clothes.
Indoors, they build up. The EPA reports that concentrations of many VOCs are consistently higher indoors than outdoors, up to ten times higher, and that activities such as paint stripping can raise levels to 1,000 times outdoor background.
Where they come from
The EPA lists these household sources:
- Paints, paint strippers, solvents and wood preservatives
- Aerosol sprays, cleansers and disinfectants
- Moth repellents and air fresheners
- Stored fuels and automotive products, including from an attached garage
- Hobby and craft supplies: glues, adhesives, permanent markers and photographic solutions
- Building materials and furnishings, including pressed-wood products that release formaldehyde
- Office equipment such as copiers and printers, and correction fluids
- Pesticides and dry-cleaned clothing
Common VOCs by name
The EPA singles out several compounds that turn up in homes. The table pairs each with its usual household source.
| VOC | Where it typically comes from |
|---|---|
| Formaldehyde | Pressed-wood products such as particleboard, plywood and fiberboard in furniture, cabinets and subfloors |
| Methylene chloride | Paint strippers and solvents |
| Benzene | Tobacco smoke and stored fuels |
| Perchloroethylene | Dry-cleaned clothing |
Health effects
The EPA lists eye, nose and throat irritation, headaches, loss of coordination and nausea, along with damage to the liver, kidneys and central nervous system; some VOCs are suspected or known to cause cancer. Effects depend on the compound, the level and how long you're exposed.
Formaldehyde, the most persistent household VOC
Formaldehyde deserves its own note because it comes from the glue, not a coating. Particleboard, plywood and fiberboard are bonded with urea-formaldehyde resins, and that resin keeps releasing formaldehyde gas slowly as it cures and ages. A thin layer of paint has a small reservoir to give off; a cabinet or subfloor made of pressed wood has a large one.
That is why formaldehyde lingers. Warmth and humidity speed the release, because heat drives evaporation and moisture breaks the resin down faster. A newly furnished or freshly remodeled room tends to smell strongest on the first warm, humid days.
Federal rules cap how much formaldehyde these products can emit. Under the Toxic Substances Control Act (TSCA) Title VI, emissions are limited to 0.05 ppm for hardwood plywood, 0.09 ppm for particleboard, 0.11 ppm for medium-density fiberboard, and 0.13 ppm for thin medium-density fiberboard. Those caps match California's Phase 2 standard, so wood labeled TSCA Title VI or CARB Phase 2 compliant meets the same limits.
How long off-gassing lasts
Emissions are highest when a product is new or in use, and fall over time. Wet products such as paint and adhesives drop off faster than furniture and pressed-wood products, which can keep releasing smaller amounts much longer. Airing out new items, ideally outdoors or in a ventilated space, shortens the worst of it.
Reading low-VOC and zero-VOC labels
Paint labels report VOC content in grams per liter (g/L), the mass of volatile compounds in a liter of product. A lower g/L number means less solvent to evaporate as the paint dries, so it is the figure to compare rather than the words on the front of the can.
Low-VOC and zero-VOC are loosely used marketing terms, not tightly defined grades. Check the g/L value on the product data sheet, and remember that colorant added at the store can raise a zero-VOC base paint's VOC content.
One more distinction matters. VOC content measures what is in the liquid; it does not measure how much the finished, dry product keeps emitting into the air over the following weeks. Independent emission certifications test that ongoing release, which a single content number cannot capture.
Testing
Consumer air monitors with VOC sensors report total VOCs as a relative reading, useful for spotting spikes when you paint or clean, but they don't identify specific compounds. Laboratory tests, which collect a sample on a sorbent tube, identify and measure individual compounds. See indoor air quality testing.
How to lower VOC levels
- Ventilate during and after use. Open windows and run exhaust fans when painting, cleaning or doing crafts.
- Follow label directions and use products only as directed.
- Don't store opened containers of paint, solvents and similar products in living spaces; buy only what you'll use soon.
- Choose low-VOC products for paint, adhesives and finishes.
- Use activated carbon for gases, not HEPA alone. The section below covers what a purifier can and cannot do.
Will an air purifier remove VOCs?
Only a purifier with an activated-carbon stage does anything about VOCs, because VOCs are gases. A HEPA filter captures particles by trapping them on its fibers, but gas molecules slip straight through it. Carbon works by adsorption: its vast internal surface area holds gas molecules until the surface fills up.
That last point sets the limit. Once the carbon saturates it stops adsorbing and can even release what it holds, so the carbon has to be replaced on a schedule, unlike a particle filter you can often see is dirty. For chemical sensitivity, more carbon by weight lasts longer.
See the air purifier guide for matching a unit to the job, and HEPA filters explained for why HEPA alone leaves gases untouched.
Source control still beats filtration. Removing or sealing the source and ventilating cut VOCs faster and more cheaply than trying to filter them out of the air.
Frequently asked questions
What are common sources of VOCs in a home?
Paints, cleaners, air fresheners, aerosol sprays, glues, stored fuels, pressed-wood furniture and dry-cleaned clothing, according to the EPA.
Are VOCs dangerous?
They can cause eye, nose and throat irritation, headaches and nausea, and some can damage organs or cause cancer at higher or prolonged exposures. Reducing sources and ventilating lowers the risk.
Does an air purifier remove VOCs?
Only if it has activated carbon or similar gas-adsorbing media. HEPA filters alone don't remove gases.
How do I get rid of the new-paint smell?
Ventilate: keep windows open and fans running for several days, and keep the room's door closed to the rest of the house where you can.
How long does new furniture off-gas?
New pressed-wood furniture off-gasses formaldehyde longer than wet paint or adhesives, because the resin inside releases gas slowly as it cures rather than drying once. Emissions are highest when the piece is new and taper over time, and warming and ventilating the room speeds the early release. Treat a lingering chemical smell as a signal to keep airing the space out.
What does low-VOC or zero-VOC paint mean?
It describes the paint's VOC content, measured in grams per liter, where a lower number means less solvent to evaporate as it dries. The terms are loosely used rather than strictly defined, so compare the g/L figure on the data sheet instead of the label wording. Tint added in the store can add VOCs to an otherwise zero-VOC base.
Sources & References
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