What are the Health Risks of Burning Candles?

by drcharles on October 13, 2013

candle healthWith 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.



{ 3 comments… read them below or add one }

Nanci October 13, 2013 at 11:34 am

I have wondered for some time about candles. I used to light a small one while taking a bath, then became concerned about what I might be releasing into the moist air in a small room so got a dimmer switch for my light instead. I do occasionally buy the aura care, I think it’s called, scented oils (real ones) that plugs in, but they don’t last long and are expensive. I still light a scented candle around Christmas. Sometimes one just has to take chances. Thanks for this article, I think my candle lighting probably falls into the safe zone.


Patrick August 8, 2014 at 8:57 am

There’s more to this story than is being told. We bought a home that the previous owners used scented candles in every room. ( Probably to mask the urine smell of cats and dogs ). Wasn’t told this.

However, upon changing the filters, we saw heavy deposits of soot on the filter. So heavy that the filter was black. Can you imagine what this does to your lungs?

Of course the health industry isn’t going to jump on to the candle makers, or, will they put warnings on candles, as they do cigarette pack, that burning candles is harmful to your health. Not only is the soot heavy, it also has an oily feel to it when I ran my finger over the filter.

I will not use candles any longer. Thank goodness I read up on this.


Israel November 4, 2014 at 6:04 pm

Thanks for writing this article. I was wondering myself if burning candles at home can cause some health related issues. Too bad there is not enough study on the subject.
It just seems logical that it is better to not light candles than to light them. After all, where does all the burned wax disappear? Breathing wax-free air is probably much better.


Leave a Comment

Previous post:

Next post: