Response: Traditional household paints contain many chemicals, including volatile organic compounds (VOCs), which are a large group of carbon-based chemicals that are volatile, meaning that they like to exist as a gas. The type and amount of VOCs in a household paint generally varies with the type and brand of paint, but traditional household paints generally contain many VOCs, including benzene, formaldehyde, and toluene. Some of these VOCs have been linked in scientific studies to bad health outcomes, including eye, nose and throat irritation, nauseau, headaches, and even cancer.
Because VOCs are volatile, they can "off-gas" from the walls into the air as the paint is applied or as it dries. This, combined with the fact that the paint is usually applied to a large area, can cause people living or spending time in these freshly painted homes to have exposures to VOCs that are much greater than normal — as much as 1000 times greater. These potentially large exposures — and resulting smells, headaches, and other potential health effects -- cause many (including you!) to look for lower VOC or chemical-free paints. There are several types of lower VOC or no VOC paints, each with their own advantages and disadvantages. Of the traditional household paints, latex or water-based paints -- especially the latex paints that are largely free of formaldehyde and other chemicals to prevent mildew and mold ("low biocide") -- have lower amounts of VOCs as compared to oil-based paints. Similarly, flat finish paints tend to contain fewer VOCs than glossy finish paints, while white or pale paints have less VOCs than brightly colored or dark paints.
Even lower in VOC content are the "low VOC", "zero-VOC" or "no-VOC" latex paints, which must have VOC levels lower than 100 parts per gallon (or less than five grams of VOCs per liter g/L in the case of "zero VOC" or "no-VOC" paints ). Although lower in VOC content, they all (even those paints labeled as "no VOC ") generally release some VOCs into the air, with the amount differing by brand. These low and no VOC paints work well, with studies showing that they work as well as or better than a conventional latex paint. However, care should be taken in selecting a "low-VOC" paint, as some may still emit relatively high amounts of certain VOCs and some may perform poorly.
Other paints are entirely free of man-made chemicals and thus are the least polluting and harmful options. "Natural" paints are composed of natural materials, such as linseed, citrus, and soy oils, pine- and balsam-derived turpenes, minerals, plant pigments, lime, and chalk. Although they are made from natural ingredients, "natural" paints may still emit significant amounts of VOCs from ingredients like turpenes or citrus oil, which can also cause eye or lung irritation in some people. "Milk-based" paints, on the other hand, emit no natural or man-made VOCs, but have limited usage (for example, not in kitchens, bathrooms, or other damp areas), take a long time to dry, and require frequent repainting.
There are several sites that provide more detailed information and/or lists of low or no VOC paints, including GreenSeal and GreenHome, which you may want to check out before deciding on a paint type. Also, you may want to look at comments on TreeHugger for other recommendations about green paints.
Previous Ask Treehugger columns can be found here.
Helen Suh MacIntosh is a professor in environmental health at Harvard University and studies how pollution behaves in the environment and how it affects people's health. Please keep in mind that her answers are just her interpretation of available information and should not be taken as the only viewpoint or solution to a problem. Use this column at your own risk. Having said this, please feel free to post any of your environmental health questions to Helen@TreeHugger.com (please use a descriptive email subject line and mention if you want to remain anonymous or not).