How To Reduce Health Hazards Of Burning Candles

Precautions To Minimize Exposure to Soot And Unhealthy Chemicals

Sep 27, 2009

Candles have improved indoor ambiances for years, however some studies show that it is worth moderating the use of some types due to emissions of potential carcinogens.

It is surprising that burning candles can give rise to health risks. This is more a question of how intensive one's candle usage is than an absolute prohibition on something people have been using for centuries. The occasional candlelit dinner a couple of times a week is unlikely to cause any problems but extensive use of scented candles in a poorly ventilated bedsit may be an issue.

What Are the Health Risks Of Candles

There are two main types of emissions from candles that are known to cause health problems in high concentrations. One is soot - the product of incomplete combustion. The lovely yellow flame of a candle is in part due to these particles being heated to incandescence in the flame, before they are carried up in the heated air stream and enter the indoor atmosphere.

In contrast, the blue flame of a gas hob is typical of almost complete combustion. It is easy enough to demonstrate the amount of soot in a candle flame is much more than of a gas flame - hold the bottom of a saucepan to the candle flame for a second or two and plenty of soot will be deposited, whereas none is deposited when it is on the stove for hours.

Small soot particles can enter the lung and be deposited in the airways, as well as causing black soot deposits in the home, which are more a cleaning problem than a health problem.

The second type of emission from candles is compounds emitted during burning, mainly organic compounds though lead is a hazard in some cases. In the past wicks were sometimes stiffened with lead wire, and these persist at a low level on the market.

A 2000 study in the Washington-Baltimore area turned up nine lead-containing wicks among a sample of 285 candles. Not all metal-cored wicks contain lead - tin and zinc are suitable alternatives without the health problems of lead.

One test for lead in the wick is by drawing some of the unburned wick against some paper - if a silvery streak like that from a pencil is left then the wick is likely to contain lead and should not be used.

Organic compounds are also produced by burning candles, though the variation in candle manufacture makes for a huge range in the emissions depending on the candles and the burning conditions.

Things One can Do to Minimise The Risks of Candle Emissions

Because softer waxes and some of the products used to scent candles increase organic emissions, there are some general rules that can reduce both soot and organic emissions

Avoid candles with metal cored wicks containing lead
Favour candles with thin braided wicks which curl as the candle burns.
Minimize the use of scented candles - the EPA found that these are a major cause of black soot deposition.
Use only candles made of solid wax, preferably a hard wax.
Burn candles in the open rather than in glass containers - these restrict the airflow and can make it turbulent which again reduces the completeness of combustion.
Keep the wick properly trimmed, either according to the makers instructions or to about 1/4 inch before lighting.
Avoid multiple wick candles - the airflow of multiple flames can interfere, causing incomplete combustion.
Stop using any candle that produced excess visible soot.
Increase ventilation when burning candles, though avoid draughts which make the flame unsteady.
Avoid using many candles is small rooms like the typical bathroom.
Consider alternatives to paraffin wax, which most candles are made of. Beeswax is a good alternative, and soy wax candles are another alternative.

There is no need to give up the romantic atmosphere that candles can lend to an evening if they are used sensibly in moderation. A 1997 study cited by the EPA tested a scenario of 30 candles burning for 4 hours in a room of 50 cubic metres volume, which indicated there was no health hazard. However the EPA did find their guideline limits for acetaldehyde, formaldehyde and acrolein exceeded in the reports of that study. These chemicals are identified as risks for cancer by the EPA.

Most people's candle usage will be considerably fewer candles for less time and probably in a larger room volume, so the risks will be reduced to lower levels. The subject of candle safety is of course, not just limited to emissions. A candle should never be left burning in a room without someone to keep an eye on it for fire safety, and a flickering flame indicates a potential fire hazard because of the instability.

Sources

Candles And Incense As Potential Sources of Indooor Air Pollution, EPA, Jan 2001 (PDF)
Candles, romance and... cancer? NHS Choices August 20, 2009

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