Indoor air quality at home: VOCs, ventilation and what certifications measure

According to the EPA, indoor pollution sources that release gases or particles into the air are the primary cause of indoor air quality problems. Too little ventilation makes things worse, because not enough outdoor air comes in to dilute those emissions and carry them out. High temperature and humidity can also raise the concentration of some pollutants.

Sources fall into two groups. Some, such as building materials, furnishings and air fresheners, release pollutants more or less continuously. Others are tied to an activity, such as smoking, cleaning, redecorating or a hobby, and release pollutants in bursts that can linger in the air long after you finish.

How much any one source matters depends on how much it emits and how hazardous those emissions are. The EPA is also frank about the limits of the science: it says there is considerable uncertainty about what concentrations or periods of exposure are needed to produce specific health problems, and that people react very differently.

Volatile organic compounds are chemicals emitted as gases from certain solids or liquids. "Organic" here is a chemistry term meaning carbon-based. It has nothing to do with organic farming.

The EPA says concentrations of many VOCs are consistently higher indoors than outdoors, up to ten times higher. Its own studies in the 1980s found levels of about a dozen common organic pollutants to be 2 to 5 times higher inside homes than outside, whether the homes were rural or industrial. During and for several hours after certain activities, such as paint stripping, levels may be 1,000 times background outdoor levels.

Three indoor air risks have little to do with what you buy for the living room, and they come before any shopping decision.

The EPA notes that no federally enforceable standards have been set for VOCs in non-industrial settings such as homes. That gap is why third-party emissions labels exist. Each one measures something specific, and none of them means organic.

New furnishings are a classic continuous source. Formaldehyde is the most familiar example. A federal rule limits formaldehyde emissions from hardwood plywood, medium-density fiberboard and particleboard, and from household goods that contain them. Since March 22, 2019, these products must be labeled TSCA Title VI compliant when sold in the United States. Our page on non-toxic sofas and furniture looks at materials and emissions certifications together.

A mattress is a large product you spend hours next to, so an emissions certification is a fair thing to ask for alongside organic materials. See organic mattresses for picks that state both.

For floors, ask what the backing and any adhesive are made of, not only the pile. Our organic and natural fiber rugs page covers that.

Candles are a combustion source whatever the wax. The EPA includes burning candles in its list of indoor particle sources. If you burn them, do it with some ventilation, and see non-toxic candles for what makers disclose.

Cleaning products are covered in non-toxic cleaning basics, and a room-by-room list for a baby's room is in our non-toxic nursery checklist.