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 emit pollutants like benzene, styrene, toluene, acetone and particulate matter. Some core wicks on imported candles have even been found to be made of lead.
Although in the past, specialists in environmental medicine have 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. If candles are not properly manufactured, or contain too high quantities of fragranced oils that are not suitable for combustion, the result could be an indoor air quality problem.
In the U.S., the National Association of Home Builders (NAHB) has been receiving an increasing number of reports about black soot deposition. A prime suspect is the increased use of candles and other indoor combustible materials including incense, potpourri and oil lamps. The problem is so severe that North America’s largest indoor air quality conference, held in Texas in mid April, 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 discolours 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 candle flames must contain soot or they will not be bright. Soot 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 candle soot 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 to candle soot.
How to Minimize Indoor Air Pollution from Candles
1. Burn only beeswax or soy candles, which burn cleaner than those made with paraffin wax, which is a petroleum product.
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 or increase flicker. Candles poured 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 any candles that leave sooty residues on candle holders or surrounding surfaces.
10. Increase ventilation in rooms where candles are burning, while avoiding direct drafts on the candles.
11. Extinguish candles after one hour of continuous burning and allow them to cool before relighting.