Tuesday, June 14, 2011

VOCs: Volatile Organic Compounds, Indoor Air Quality and Respiratory Health

Volatile organic compounds: something's in the air

You can't see them, but they're all around us. They aren't listed as ingredients on the objects we bring in our home, but they're often there. They're volatile organic compounds, or VOCs, a wide range of carbon-based molecules (organic compounds) used in a wide range of products that find their way into our homes. Under normal conditions, they vaporize, effectively leaving their host and entering the air (that's the "volatile" part) where they combine with other airborne compounds to form ozone, which isn't good to breathe.

Though they exist everywhere in the environment -- the most common volatile organic compound is methane, which comes from everything from wetlands to cow farts and other ruminant gases to rice agriculture -- they are most well-known for the harm they can cause indoors, where they can be introduced via paint, carpets, furnishings, and cleaning agents.

here do volatile organic compounds cause problems?

Indoor environments are where volatile organic compounds are most dangerous to us; they contribute to poor indoor air quality, which the U.S. Environmental Protection Agency estimates is often two to five times worse than the air outside, but concentrations of VOCs can be up to 1,000 times greater indoors than out! CommonVOCs include formaldehyde, used in many glues and adhesives, including those found in wood veneers, plywood and particle board, and polyurethane, which is used in many foams, paints, varnishes, and construction sealants.

VOCs and respiratory health

As we noted in our Green Basics column about indoor air pollution, if there are volatile organic compounds in a product, there are VOCs that can off-gas into the air, creating a danger to human health when they do. At high concentrations, some VOCs can cause chronic and acute health effects; others are known carcinogens. But even low to moderate levels of multiple VOCs can produce acute reactions. Bottom line: Avoidvolatile organic compounds as much as possible.

Oddly, VOC regulation varies from country to country; learn more about VOC definiton and regulation near you.

VOCs: different definitions in different places

Interestingly, though they're all the same substances, the definition of "volatile organic compound" varies by locale. The U.S. EPA defines VOCs as "any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photochemical reactions," but also includes a list of dozens of exceptions for compounds "determined to have negligible photochemical reactivity."

Volatile organic compounds and air quality standards

Under European law, the definition of a VOC is based on evaporation into the atmosphere, rather than reactivity, and the British coatings industry has adopted a labeling scheme for all decorative coatings to inform customers about the levels of organic solvents and other volatile materials present. Split into five levels, or "bands", these span minimal, low, medium, high, and very high.

In the U.S., various rules apply to labeling products, too. A "no-VOC" paint, for example, must have fewer than five grams of VOCs per liter; latex paints containing less than 250 grams per liter and alkyd paints with less than 380 may be labeled as "low-VOC." However, adding pigment typically adds VOCs, and since testing is typically completed before color is added, VOC levels can vary widely from these parameters.

Avoiding volatile organic compounds and improving indoor air quality

Water-based glues, adhesives, finishes, and soy-based foams will help keep VOC levels to a minimum in furnishings and decor. Buying green cleaners helps ensure that you aren't adding toxins to the air when you clean them.

For further reading, check out green household paint alternatives, learn how to monitor VOC levels in your home and get the low-down on "vapor intrusion". VOCs contribute to Sick Building Syndrome (which is another post), and the EPA has good basic info on how the two relate, and more info on VOCs. Get the facts, and start breathing easier in your home today.

Breathe fresh green goodness with our Green Basics column, which appears regularly on TreeHugger.

Now that you know what they are, learn how to avoid VOCs.
Post a Comment