THE DETAILS: Most of the candles on the market are made with paraffin wax, derived from petroleum, and scented with synthetic fragrances, also derived from petroleum. Less common are candles made from plant oils like soybean, palm, or hemp, or from beeswax. The researchers for this study took paraffin wax and soy wax candles and burned them for five to six hours inside a chamber, measuring the kinds of chemicals that could be emitted by burning candles. They found varying levels of cancer-causing toluene and benzene, as well as other hydrocarbon chemicals called alkanes and alkenes, which are components of gasoline and can irritate respiratory tracts and trigger asthma. Ruhullah Massoudi, PhD, professor of chemistry at South Carolina State University and lead author of this new study, says that his research didn't reveal the exact amounts of the pollutants he found, only that they were there.
WHAT IT MEANS: Chemicals that reduce your indoor air quality aren't the only problem with paraffin candles. Previous research into candle pollution has found that candles can emit ultrafine, lung-damaging particulate matter that's capable of penetrating deep into the lungs. Massoudi adds that candle soot can deposit on furniture, in carpeting, and in walls, lingering for long periods of time. A study from the Canadian Mortgage and Housing Authority found that candles can contribute to everything from stains on carpet to black dust on household surfaces and blackened, greasy air filters.
The amount of soot and chemicals produced by a single candle can be hard to predict, as well. An Environmental Protection Agency report on candles and indoor air quality found that one type of candle could emit 100 times more soot than another. While burning a single paraffin-wax taper or tea light now and then probably won't pollute your home, frequent candle users may want to look for alternatives to keep their indoor air quality as healthy as possible.
Try these tips to enjoy candles without polluting your indoor air:
• Support your local beekeeper. Paraffin candles release chemicals because of improper combustion: The flame doesn't get hot enough to burn the oil completely, and chemicals are released as a result, Massoudi writes in his study. Beeswax candles burn at lower temperatures and don't have that problem. They also smell sweet without any added chemical fragrances, and some people believe that the negative ions in the wax actually improve your indoor air quality as the candles burn.
• Don't burn GMOs or rain forests. Massoudi compared the paraffin wax candles in his study to soybean wax candles, which didn't emit any of the pollutants that the petroleum-based paraffin did. However, many soy candles are made from genetically modified (GMO) soybeans, which decrease biodiversity and can contaminate organic soybean crops. Palm oil, another vegetable wax used in candles, comes from palm tree plantations, for which rain forests were burned or clear-cut.
• Buy the right kind of oils. In this case, essential oils. Even beeswax and plant wax candles can be scented with synthetic fragrances, which can contain phthalates that can interfere with your hormone system. Phthalates can also build up in household dust and linger for long periods. So if you're going for scented candles, look for ones that are scented with essential oils rather than chemical fragrances.
• Trim the wicks, and use your common sense. Keeping wicks trimmed to about ¼" will cut down on any soot that may come from candles, soy wax, beeswax or otherwise. Also, keep candles out of drafty windows where drapes may come in contact with the flame, and don't leave them unattended.
• Use outdoor air to improve indoor air. If you're burning candles to improve the smell of your home, you're going about it the wrong way. "Some people just don't open the door and get fresh air in their homes," says Massoudi. That's a lot more effective at freshening up a space than polluting candles can be.