Candles are calming, smell great, create ambience, and always score as a favorite house-warming gift. But you may have heard that they can also spew toxic, cancer-causing chemicals into the air. These rumors may leave you wondering, Are candles bad for you or the environment?
Don’t panic. There’s no need to throw away your luxe stash. While candles do release vapors and particles into the air while burning, you should not be concerned about any negative impact on your health, says Pamela Dalton, PhD, a lead researcher in odor perception and irritation at Monell Chemical Senses Center.
“People always talk about how a candle contains formaldehyde and benzene, but they never talk about the amount of any chemical that’s present,” she says. “It’s not simply a chemical’s presence or absence, because we’re surrounded by chemicals all the time in indoor air and outdoor air, but it’s the concentration that matters.”
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And unless you have a million candles in a small space with no ventilation, the levels of chemicals you breathe in from your favorite scented candles are really low, says Karin Pacheco, MD, an allergist at National Jewish Health in the Division of Environmental and Occupational Health Sciences.
Okay, so is it reasonable to assume that candles are totally safe? For the most part, yes. But you should still be cautious about what types you burn and where and how you use them to minimize any possible harmful effect. Here’s everything you need to know to keep reaping the relaxation benefits and avoid any potential downsides, according to experts.
Meet the experts: Pamela Dalton, PhD, is a member of the Monell Chemical Senses Center, where she studies odor and sensory irritation from volatile chemicals.
Nikaeta Sadekar, PhD, is a respiratory toxicologist at the Research Institute for Fragrance Materials, an international authority for the safe use of fragrance materials.
Arvey Stone, MD, is a pulmonologist affiliated with Advocate Lutheran General Hospital.
Are candles really bad for you?
Let’s clear the air: Candles can produce and vaporize particles that could be unsafe if inhaled at an extremely high dose, but your average candle will not harm you, says Dr. Pacheco. “Most wax is made out of paraffin, which is derived from petroleum and can produce formaldehyde, benzene, acetaldehyde, and polycyclic aromatic hydrocarbons,” she says. “But these chemicals are at very low concentrations, and harmful lead-containing candle wicks have been banned since 2003.”
So, yes, a candle does technically put out small amounts of chemicals that could be bad for you, but studies have found that the amount of released chemicals is not enough to cause health problems. And there is no significant association between candles and heart disease, pneumonia, or lung cancer, according to a 2022 study published in the journal Indoor Air.
The chemicals released from a candle are at very low concentrations, so your average candle will not harm you.
And remember that everything is relative. “At some concentration, almost every chemical that is used in the fragrance or candle industry has the potential to produce some irritation, like your nose tingling or your eyes watering,” says Dalton. But that potentially harmful threshold is way higher than what you’d get with any scented candle.
If you do feel a little irritated after lighting a candle, you’re likely reacting to the fragrance itself. “Everyone has a different sensitivity, but there is nothing in commercial candles that is harmful in the long term from a fragrance perspective,” notes Dalton.
Some people have compared candle vapor to secondhand smoke. Are candles as bad as cigarettes?
If you’re worried about this, you can breathe a sigh of relief. The difference between the two lies in the temperature at which they burn. “Smoke produced from a cigarette is basically a smoldering, low-temperature combustion, and the temperature that cigarettes are burning at contributes to the formation of cancer-causing chemicals,” says Paul Guentert, MD, a pulmonologist at Saint Joseph Pulmonology.
With a candle, on the other hand, you get a higher-temperature combustion with not much coming out of it. And incinerating something at a very high temperature breaks it down to the base molecules, which tend to be less toxic than if something is smoldering like a cigarette, explains Dr. Guentert.
That being said, if you have multiple candles burning for long periods of time (like in a church), there will be an accumulation of soot. FYI: Soot is a combination of partially burned carbon, which can stick to walls or ceilings and cause health issues like heart disease, asthma, and even cancer if ingested or inhaled. But unless you have many candles going at the same time 24/7, there’s no need to worry about soot buildup in your home.
Are candles bad for the environment?
Since the amount of chemicals used in candles is very small, there are no concerns about any adverse effects on the environment, says Nikaeta Sadekar, PhD, a respiratory toxicologist and senior scientist at The Research Institute for Fragrance Materials.
“The chemical concentration in candles is so small, there is virtually no environmental impact from a single consumer using a product,” says Dalton.
Candles do produce volatile organic compounds, a.k.a. carbon compounds that can easily turn into a gas at room temperature, but they evaporate almost immediately, says Sadekar.
The bigger environmental concern is if a candle manufacturer has a spill. “If large quantities of fragrances in high production volumes spill, that is concerning for waterways until it is diluted,” notes Dalton.
How do you minimize the harmful effects of burning a candle?
First things first, make sure you light candles in a well-ventilated space. “Don’t light candles in your closet or in a bathroom with the doors and windows closed,” says Dr. Pacheco. “Light them in an open area where you have some sort of air movement.”
Another pro tip: Choose candles made with natural ingredients. Candles made from palm oil release half the amount of soot as paraffin ones, and natural candles made from coconut, soy, vegetable, and beeswax release the lowest amounts of potentially harmful chemicals, according to a 2013 study in the journal Bulletin of Environmental Contamination and Toxicology. And since paraffin candles are derived from petroleum in the first place, stay on the safe side and look for the more natural options that do not emit the same kind of chemicals, says Dr. Pacheco.
In addition, if you or someone in the room suffers from asthma or a chronic lung condition like chronic obstructive pulmonary disease (COPD), studies show candles could exacerbate symptoms. “If you have otherwise sensitized airways like in asthma or COPD, then any type of heavy odor or fumes are going to be a problem,” Dr. Guentert says. In these cases, it’s best to avoid candles all together, or light non-scented candles in a large room.
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How do you use candles safely?
Again, keyword: ventilation. “If you burn candles in a large space, the volume of air in the room will disseminate the candle-related gasses so you aren’t breathing in any high concentrations” says Arvey Stone, MD, a pulmonologist at Advocate Lutheran General Hospital. Any type of flame needs ventilation, so just be mindful of where your candles are burning.
Also, trim the wicks before each burn. Untrimmed candle wicks can cause uncontrolled flames, smoky, black residue in the jar, and produce extra smoke that can lead to more soot, according to the National Candle Association. To prevent any danger (and keep your candles looking good!), make sure to cut the wick to about one-fourth inch and remove any debris (like wick trimmings and broken matches) before each use.
Lastly, don’t leave open flames unattended, says Dr. Guentert. Regardless of any minimal health risks, make sure you blow out all candles before you go to sleep and keep open flames away from children and pets.
The bottom line: Limit yourself to burning one to two candles at a time, and always make sure you have plenty of air circulation when you do that.
Andi Breitowich is a Chicago-based writer and graduate student at Northwestern Medill. She’s a mass consumer of social media and cares about women’s rights, holistic wellness, and non-stigmatizing reproductive care. As a former collegiate pole vaulter, she has a love for all things fitness and is currently obsessed with Peloton Tread workouts and hot yoga.