With colder weather and fewer hours of light I have been increasingly lighting candles in my home. I enjoy the meditative, calming moment that a flickering flame instantly conjures. Humans have an innate affinity for fire light. Perhaps that attraction has been wired into our DNA, providing a survival benefit for those ancestors who did not run from the fire into a dark, cold night of predators. But is this cozy habit an overall detriment to our health now that we live in enclosed houses? I think the answer is far from clear, but there are some issues to consider that have given me pause in lighting another candle tonight.
The combustion of any product releases a multitude of chemical byproducts. It would seem that candles made of paraffin, which is derived from petroleum, would release many potentially harmful volatile organic compounds. Some studies have born this out, although concentrations seem small in relation to what is generally considered toxic.
For example, a study out of the University of South Carolina evaluated both paraffin (petroleum-based) and soy (vegetable-based) candles, none of which contained any scents, pigments, or dyes. The author noted that burning paraffin candles released alkans, alkenes, and even toluene, chemicals that in high enough concentrations can cause respiratory tract irritation and even cancer. This study was part of a research grant, however, and I could not find it published by any peer-reviewed journal. It’s author, Dr. Ruhullah Massoudi, has made blanket statements that soy-based waxes did not release any harmful substances when burned. His work was funded by the Dept. of Agriculture, which heavily subsidizes the soybean industry.
The EPA has commented on the burning of candles, and added in a 2001 report that burning candles can lead to variable concentrations of formaldehyde, acetaldehyde, acrolein, and plain old soot which penetrates deep into lung tissue. There have been other studies showing essentially no difference in the emissions from paraffin, beeswax, and vegetable-based candle wax, and that burning all types releases hundreds of chemicals, not all of which are considered harmful of course.
Scented candles, especially those with artificial scents instead of essentials oils, may also produce a wide variety of potentially harmful by-products when burned, including phthalates.
But the direct evidence that burning candles may cause harm is really lacking, at least in terms of my search tonight. There are very few studies, and the quality of these studies is generally poor. It is really hard to find good advice on this subject, but in general these principles seem intuitive:
Candles may be therapeutic in terms of relaxation for some people.
Vegetable and beeswax candles may emit less potentially harmful chemicals, but even these are creating numerous byproducts of combustion.
Scented candles, especially synthetic fragrances, add another layer of nebulous complexity to the emissions profile of burning.
Limiting the burning of candles, and ensuring good home ventilation, seem prudent ideas given the lack of hard science on this whole topic.
It is likely that more harm is done to people by direct thermal injury from flames than chemicals released during candle burning.
The bottom line is that you are burning something when you light a candle of any kind.
Living plants, on the other hand, take in carbon dioxide and are dutiful bio-accumulators of airborne toxins, and I also find that they resonate with the primal human need for elemental, earth-bound comfort.
And as for alternatives, flickering LED candles actually depress me, so there may be negative psychiatric effects of sallow, artificial replacements, too.