by Wendy Priesnitz
I’d never allow someone to smoke a cigarette inside my home or office. And yet, until recently, I never thought twice about burning candles…scented or otherwise, for romance or for stress relief. However, an increasing number of indoor air quality scientists are sounding the alarm about the ability of candles to create indoor air quality hazards by emitting pollutants like benzene, styrene, toluene, acetone, and particulate matter. That is because many candles, and especially the more inexpensive ones, are made from paraffin wax, which is a petroleum-based product. Also, aromatherapy and other scented candles may contain fragranced oils that are not suitable for combustion. In addition, some core wicks on some imported products have been found to be made of lead; although that is illegal in many areas, they are still widely available.
Although in the past, specialists in environmental medicine had occasionally noted problems resulting from candle use, indoor air pollution and related health problems appears to becoming more common due to the popularity of scented and aromatherapy candles.
In the U.S., the National Association of Home Builders (NAHB) has been receiving an increasing number of reports about black soot deposition in people’s homes. A prime suspect is the increased use of indoor combustible materials including incense, potpourri, and oil lamps. The problem is so severe that North America’s largest indoor air quality conference featured a workshop that presented the latest research and case studies on the effects of black soot from candles.
Soot is a product of incomplete combustion of carbon-containing fuels, usually petroleum-based. The soot not only discolors walls and furniture, it can also contaminate your home’s ventilation system. Although the problems resulting from burning candles can be minimized, the basic problem is that the flame must contain soot, which is the source of the bright white/yellow light that candles emit. A flame without soot will burn blue, like the flame from a gas stove.
While little or no research has been conducted into the health effects of exposure to candle soot, studies into the risks of exposure to soot from diesel exhaust and factory emissions suggest it can be harmful. Since soot particles are typically very small, they can potentially penetrate the deepest areas of the lung. Researchers caution that the very young, the elderly, and those with respiratory diseases like asthma, should avoid exposure.
How to Minimize Indoor Air Pollution from Candles
1. Burn only beeswax or soy candles, which burn cleaner than those made with paraffin wax.
2. Ensure the wick is the correct size for the thickness of the candle. Avoid too thick wicks and those with a wire core that keeps the wick upright. Burn candles with thin, braided wicks that curl over when burned. The wick should burn down evenly with the wax.
3. Avoid multiple wick candles.
4. Trim the wick to ¼ inch before lighting.
5. Keep your candle in a draft-free area. The goal is a low, even flame.
6. Don’t burn your candle in a narrow mouth container, which will cause unsteady air flow and increase flicker. Candles made by pouring wax into glass jars or ceramic containers can often be problematic.
7. Only burn candles made of hard wax.
8. Avoid highly aromatic candles. Ensure the scent used in the candle is specifically formulated for candles and avoid wax that contains volatile aromatic hydrocarbons.
9. Cease burning a candle that leaves sooty residues on the holder or surrounding surfaces.
10. Increase ventilation in rooms where they are burning, while avoiding direct drafts on them.
11. Extinguish after one hour of continuous burning and allow them to cool before relighting.