As the Christmas season unfolds, many are lighting their holiday candles to fill their homes with scents of gingerbread, fresh balsam and cinnamon swirl.

But behind the cozy flicker, is there a lingering toxin filling the air in your home?

Social media is filled with posts warning about the hidden dangers of scented candles, claiming they release harmful chemicals into the air and can irritate the skin, especially for those with sensitivities.

However, experts and studies suggest that many of these claims lack scientific evidence and may be fanning the flames of unnecessary fears about the risks associated with scented candles.

Candles do release chemicals into the air, just like other household supplies, like cooking fumes, air fresheners and cleaning supplies, explained Pamela Dalton, an odour perception and irritation researcher at the Monell Chemical Senses Center in Philadelphia, Pa.

“But I believe the fear is blown out of proportion,” she told Global News, adding that candles burn and release a “trivial concentration” of chemicals in the home.

Scented candles can release pollutants like volatile organic compounds (VOCs), including benzene and formaldehyde, particle matter and carbon monoxide. Some candles with metal-core wicks can release lead when burned, Health Canada warned.

While lead exposure is a health concern (and Health Canada advises against lead-containing candles), Dalton noted that chemicals like benzene and formaldehyde in candle emissions may sound alarming but aren’t always as harmful as they seem.

“Social media has a way of sort of inflaming a lot of these concerns. And when you say something emits benzene or formaldehyde to someone, the average person may not understand that there are thresholds for effects from everything, including salt and water — that at some point, everything can become a toxin,” she said.

She noted that numerous studies have shown burning a candle — whether scented or unscented — releases chemicals at levels far below the threshold considered toxic to humans.

“Even in the smallest spaces, under the conditions that they tested, there were no meaningful concentrations that would cause anyone alarm,” she said.

Most scented candles contain a combination of natural and synthetic fragrances.

These fragrance materials may be derived from natural sources (such as essential oils) or synthetic aroma chemicals (to enhance the scents), according to the National Candle Association.

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VOCs and particle matter are released from candles as a natural byproduct of their composition and the way they burn. Many candles, particularly scented ones, contain volatile substances like fragrance oils that evaporate when heated, releasing VOCs into the air.

In a 2014 study published in Regulatory Toxicology and Pharmacology, researchers looked at the health risks of particulate emissions from candles in indoor environments. The study found that cancer-causing chemicals like benzene and formaldehyde were emitted by scented candles.

“Most indoor pollutants consist of chemicals stemming from various sources including outdoor, indoor combustion sources such as tobacco smoke, heating or cooking, and burning of candles,” the authors wrote.

However, the researchers concluded that under normal conditions of use, scented candles do not pose known health risks to the consumer.

A 2015 study published in the Journal of Hazardous Materials investigated whether different scented candles release varying chemicals. The researchers discovered that the strawberry-scented candle emitted the highest amount of formaldehyde. They also found that some scented candles released excessive VOCs even before being lit.

The authors concluded that certain scented candle products should act as potent sources of VOC emission in indoor environments, regardless of conditions — whether being lit or not.

A 2021 study in Environmental International analyzed emissions from candles made of different waxes (palm, paraffin, soy, stearin) with and without fragrances.

Unscented candles produced significantly lower emissions compared to scented ones, the study found. Floral, fresh and fruit fragrances led to higher VOC emissions than spice scents, due to differences in fragrance volatility.

And while ultrafine particle emissions were highest during the first 30 to 60 minutes of burning, levels of toxic gases like carbon monoxide and formaldehyde stayed within safe indoor air limits, the study concluded.

In an email to Global News on Thursday, a spokesperson from the National Candle Association said, “Typical fragranced candle emissions are well below the most conservative safety limits set by regulatory authorities and safety organizations, and they are safe for use in the home.”

While emissions from candles, including VOCs and particle matter, typically remain well below thresholds established for safe indoor air quality, individual sensitivities can still occur, Dalton said.

Some people may experience adverse reactions to certain fragrance components or soot particles, even at low levels.

Any kind of combustion byproduct has the potential to be irritating, Dalton explained.

If a candle produces excessive smoke or irritates your eyes, it might mean you are using it incorrectly, she said, such as a wick that’s too long or debris in the wax pool.

Ensuring proper candle care, like trimming the wick and using candles in a well-ventilated room, can minimize these issues, Dalton added.

“If you’re burning candles and your eyes are starting to become irritated, then perhaps you should either choose a different candle or put it out,” she said. “I think you can really trust your nose to let you know if you know something is going to become an irritant.”

She added that burning a candle made from paraffin wax, which is derived from fossil fuels, may result in a higher likelihood of chemical emissions compared to candles made from soy or beeswax.

However, soy and beeswax candles tend to be more expensive.

“If if the fragrance bothers you, but you still just like the ambiance of a candle, just go for a fragrance-free candle.  I think you can trust your sensory systems to let you know when something is potentially an irritant and either cut back on the use or ditch that candle,” Dalton said.

She also added there are, “probably way more other things that are emitting things in your home that you might be concerned about besides lighting a candle every now and then.”