Does Candle Burning Pollute Indoor Air?

Indoor candle burning does pose a pollution hazard. The seriousness of the pollution is based on the specific chemicals involved in the internal wick structure and the candle's wax composition, the indoor air exchange rate, the length of time you may be exposed to any pollutants, the effects of burning any compound chemical adding scents, fragrances, and/or colors to your candle, and the byproduct particulates (soot) on your indoor environment.

Chemistry-Wicks

• A combustible strand of fibers is used to sustain the flame and draw the liquid candle's fuel (wax) toward the heat source. Candles used to be manufactured with lead-core metal wicks for structure, so the melting wax would not collapse the candle. The National Candle Association working with the ASTM International (formerly the American Society for Testing and Materials) spearheaded the development of industry standards for United States candle manufacturing and helped establish a ban on all lead-core wick candles in the United States effective in 2003. Candles are still found on the market with lead-core wicks, but they are identified as mostly imports in a report by the United States Environmental Protection Agency.

  Lead-core wicks are a "source of airborne lead when burned," causing air concentrations "above EPA-recommended thresholds," according to the scientific literature search conducted by the authors of the EPA report. That finding was consistently found in all analytical studies they reviewed. Cores made from tin or zinc did not exceed EPA thresholds for their combustible byproducts when burned.

Chemistry-Wax

• Wax has become a generic term for the primary combustible substance used to make candles. Wax is made from a variety of common materials such as beeswax, paraffin, and soy, and synthetic formulations scientifically blended for burning characteristics and shape holding ability. The type of wax used in your candle may also contribute to indoor air pollution depending on your particular genetic bias for allergies and its particulate composition when burned. "In addition to lead, consumers are exposed to concentrations of organic chemicals, such as formaldehyde, acetaldehyde, and acrolein," according to the EPA study cited, although the conclusions of the tests studied varied on whether those substances exceeded EPA-thresholds

Rate of Air Exchange

• Heating, ventilation and air conditioning (HVAC) systems are designed to provide a specific rate of air exchange. Your rate of air exchange may help in reducing your exposure to pollution. The more rapidly your HVAC system exchanges the air in your room the less the particulate concentration in any room at any one time. The downside is that your air exchange system will distribute the pollutants throughout the rest of your building.

Length of Exposure

• The amount of time you are in a candle-burning environment dictates your exposure to the chemicals produced. Your level of tolerance is affected by your particular genetic bias, the size of the specific pollution particulates, and the cumulative affect of those burning byproducts on human tissues.

Scents, Fragrances and Added Colors

• Burning chemicals produces byproducts-some visible, some not. The specific combination of added colors, scents and fragrances constituting your candle's makeup will affect its pollution properties.

Soot

• Particulates are released when combustion is incomplete producing soot. The amount of soot produced varies depending on the type of candle burned and the heat, fuel and air conditions affecting the combustion. Cleaning soot from walls and other surfaces takes effort. Remember, that your air exchanger will distribute the soot to other rooms as well.