August, 2008

What the Heck is a VOC?

Possibly the most widely used term in green building, a definition of VOCs is in order.

By John Wagner

Some things, like marriage and the Electoral College, seem to go along just fine as long as you don’t talk about them or try to understand them. Such is the case with volatile organic compounds, commonly known as VOCs. The term is the mostwidely used acronym in green building, but a look of panic usually crosses the average guy-in-the-yard’s face when he’s asked to define or explain it.

Very simply, a VOC is a “carbonbased” chemical compound that evaporates at room temperature. Gasoline is a VOC, because it is a hydrocarbon and fumes pour off it at nearly any temperature.

How did VOCs end up in building products? Well, for products that dry or cure—such as caulks, sealants, adhesives, and paints—they have to be applied in liquid form. To make paint, urethane, rubber, glue, etc. temporarily into a liquid so it can be applied, you need a solvent. Until these products were re-engineered to use water as a solvent, many manufacturers used (or still use) chemical VOCs.

For instance, if you want a rubber sealant between a window and a stucco wall, you can’t apply stiff rubber, so the rubber is liquefied with xylene or benzene, both petroleum derivatives, and both VOCs. The VOCs “flash off” (evaporate) to leave the stiffened rubber behind. Unfortunately, when VOCs flash off, the resulting fumes can enter people’s lungs, living spaces, and the atmosphere, and that’s when the trouble starts.

There is one area where VOCs are not like marriage and the Electoral College. Everyone universally believes they are bad for your health and should be reduced or avoided. (Talking about VOCs here, not marriages!)

Why?

Depending on their concentrate, VOCs can cause “eye, nose, and throat irritation; headaches, loss of coordination, nausea; damage to liver, kidney, and central nervous system. Some organics can cause cancer in animals; some are suspected or known to cause cancer in humans,” according to the ever-cautious EPA. And VOCs react with sunlight and the atmosphere to create smog.

That said, VOCs do play an important role in the performance of some products, and it may be that you take a “hit” by
using a product that has some VOCs to achieve superior performance and a moredurable (and therefore greener) finished product, such as a waterproof house or a harder floor finish.

On balance, it’s greener in the long run to use a floor finish with some VOCs than to use a less-durable product that needs to be stripped and refinished three times more often.

The same principle is true with urethane caulks and sealants. In the area of caulks and sealants, a pure urethane product off-gasses just CO2, but some products have VOC solvents that act as surface primers, so the caulks and sealants get better seals and offer better performance.

Also note that some products contain VOCs, yet they don’t get into the atmosphere at concentrations that are dangerous. Formaldehyde is one of those VOCs. A carcinogen commonly used in adhesives (sheet-good wood products, MDF, and batt insulation), formaldehyde in products that are “low-emitting” does not create a known health hazard. In fact, OSHA regulates formaldehyde and has adopted permissible exposure levels. Some insulation companies have formaldehyde in their insulation (it’s in the adhesive that binds the fiber), but they have the product tested by a third-party, or they have subscribed to the toughest state standards, such as California’s, to show the formaldehyde does not off-gas at hazardous levels.

You mostly find VOCs in paints, finishes, caulks, sealants, and adhesives. Here, the EPA has set the standards. For products to call themselves “Zero-VOC,” they must contain less than 5 grams of VOC per liter. For products to call themselves “Low-VOC,” they must contain < 250 grams per liter. (Or <380 G/L for alkyd paint.)

Look for zero-VOC or low-VOC products as your greenest alternatives.

The award-winning author of 10 books and a sought-after green trainer and keynote speaker for dealer events, JOHN D. WAGNER is the Green Editor for LBM Journal and the content manager for the Certified Green Dealer Program. John.Wagner@LBMJournal.com