Are scented candles bad for you? What the science says

Whether candles are a threat to your health depends on multiple factors, experts say. (Anastasiia Krivenok/Moment RF/Getty Images/File via CNN Newsource)

If you’re a candle lover, you have probably seen some brands offer soy or beeswax versions as natural alternatives to typical wax options. But are conventional candles actually bad for you? And if they are, how much better could the ones marketed as “healthier” or “nontoxic” really be?

Concerns about the safety of candles are rooted in the chemical reactions that occur when you burn them, as well as in the artificial fragrances and colorants that contribute to the various scents you may love.

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The candles of chief concern are those made from paraffin, which is a cheap byproduct primarily sourced from the refinement of petroleum. Paraffin is the most used candle wax worldwide, according to the National Candle Association, the major trade association representing US candle manufacturers and their suppliers.

However, few studies on candle emissions or their potential effects on human health exist, and conclusions from the research are mixed.

There is no overall conclusion that paraffin candles either will or won’t harm your health, said pulmonologist Dr. Sobia Farooq, a clinical assistant professor at the Cleveland Clinic’s Lerner College of Medicine.

But the risks may also depend on various factors including candle type and quality; how often and how long you’re burning it; the airflow in the space where you’re burning it; your health status; and more.

Below, experts share the science behind potentially harmful candle emissions, their concerns surrounding the lack of regulation, and ways to make the best decision for you.

What the candle science shows

When you burn a paraffin candle, it releases volatile organic compounds, or VOCs — gases that easily and quickly vaporize into the air at room temperature, said Dr. Ariful Haque, a physician researcher at Yan’an Hospital Affiliated to Kunming Medical University in China, via email.

These compounds are commonly emitted from paints, cleaning products, cosmetics, air fresheners, car exhaust, fuel-burning appliances such as gas stoves, and more, according to the American Lung Association. Some VOCs are harmful on their own, while others can react to other gases and form pollutants once they are in the air.

One of the VOCs often emitted from candles is toluene, a clear, colorless vaporized liquid that has a distinctive smell and naturally occurs in crude oil.

Toluene is registered as a toxin with established exposure limits by some regulatory agencies, including the US Environmental Protection Agency, the US Centers for Disease Control and Prevention, and the Occupational Safety and Health Administration. That’s because it’s a neurotoxin associated with dizziness, headaches or more serious effects at prolonged exposures, Haque said.

Benzene, a known carcinogen, is another VOC released by paraffin candles, Haque added. Long-term exposure to this chemical has been linked to blood disorders such as leukemia. When inhaled, benzene can also be a respiratory irritant.

Paraffin candles also emit the VOCs polycyclic aromatic hydrocarbons, which contain benzene and formaldehyde, another known carcinogen to humans.

“A good number of studies have assessed candle emissions under controlled settings as well as in homes and shown that burning candles contributes to poor air quality and increases the risk of inhalational exposure to chemicals of concern,” said Dr. Sarah Evans, assistant professor of environmental medicine and climate science at the Icahn School of Medicine at Mount Sinai, via email.

Some evidence also suggests that candles may emit toxins even when unlit, according to an April 2015 study that simulated indoor use.

The air concentrations of VOCs found in some candle studies have been insignificant when compared with levels previously deemed unsafe. Other research, however, suggests the opposite — in the April 2015 study, the concentration of formaldehyde emitted from a lit strawberry-scented candle amounted to 2,098 parts per billion, which far exceeds the 0 to 400 parts per billion range various sources consider acceptable. A lit kiwi-melon scented candle had a total emission concentration of 12,742 parts per billion.

Now, candles made from soy wax, beeswax or stearin (coconut oil or animal fats) are often considered healthier. But anything that is burned emits harmful particulates or chemicals, Evans said — so, these candles also release VOCs into the air. It’s just that paraffin wax is usually more polluting, according to some studies.

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The risk of toxic emissions is greater when candles are scented or dyed, which is another reason why paraffin-free candles aren’t immediately in the clear. This is because artificial fragrances also have VOCs, including phthalates, which have been linked to learning and behavior problems, obesity, impaired development of the reproductive system and more, Evans said. The unscented candle in the 2015 research also caused concerning concentrations of toxins but had the lowest amount compared with its scented counterparts.

The National Candle Association maintains that candles are “safe for use in the home,” a spokesperson said in a statement.

The association’s stance is based on an October 2021 study that consisted of burning 24 soy and paraffin candles, scented and unscented. However, the research was a joint effort between the NCA, the European Candle Manufacturers Association and the Latin American Candle Association. (The NCA’s members include some of the most popular conventional candle companies and one of the largest oil companies in the world. The association is also headed by people employed at top conventional candle brands.)

Additionally, there is hardly any regulation on candles, Evans said. On its website, the NCA states that its members adhere to ASTM International (formerly the American Society for Testing and Materials) standards. But “the ASTM standards pertain to fire safety and packaging, not to candle composition,” Evans added. “ASTM standards are voluntary and not enforced; products are not checked for compliance.”

There are no regulations that require complete labeling of candle contents and no third-party testing to verify manufacturers’ claims, she added.

This lack of oversight is why companies can label candles as “soy-based” even if only a small percentage of the wax is soy, depending on the region and labeling standards, Haque said.

Ways to more safely scent your home

Some of the chemicals potentially emitted by candles leave the body quickly while others may accumulate over time, Evans said. Only a few studies have examined the direct human health outcomes of burning candles. However, according to Evans, “we can extrapolate from what we know about the adverse health effects of these (products of combustion) in other settings.”

Taken together, there is sufficient evidence to suggest that burning candles in the home has the potential to be harmful to health and may be worth eliminating from the long list of pollutants many people are exposed to every day, Evans said.

Vulnerable individuals in particular should consider this guidance. Those groups include people with respiratory issues such as asthma or chronic obstructive pulmonary disease, Farooq said.

All considered, Evans doesn’t ever burn candles and discourages doing so, she said. Farooq, the pulmonologist, on the other hand, does use candles. She’s just careful about what she buys and where she burns them, she said.

Evans’ advice even goes for candles scented with essential oils — some people consider these to be harmless, but that’s not always true since burning them can alter their chemical composition, Haque said.

“Some studies find that diffusion of essential oils causes breathing problems and interferes with memory and decision-making,” Evans said. “Some types of oils are toxic to children and pets. It can also be difficult to verify the purity of essential oil products that may contain a mixture of harmful chemicals. Like candles, essential oils are not regulated or tested to ensure they are free of contaminants.”

Visit these sites to learn which essential oils may be harmful for children, cats and dogs.

If you want to continue using candles, experts have some tips for how you can minimize any potential health risks:

• Choose candles labeled as 100 per cent soy wax, beeswax or stearin wax when possible.
• Ensure the wick is cotton, wood or synthetic, and free from cores made of metals including lead or zinc. (Lead wicks have been banned in a few countries, including the United States, Australia and Denmark.)
• If you simply can’t resist using scented candles, look for those with essential oils or candles labeled as phthalate-free.
• Avoid dyed candles.
• Keep lids on candles when not using them.
• View the manufacturer’s website or contact the company to learn more about the composition. Some components, such as fragrance, are considered trade secrets, so manufacturers may not disclose individual chemicals, Evans said.
• Burn candles in a well-ventilated area to reduce indoor air pollution from any soot, VOCs or smoke. Keep the area ventilated after blowing candles out. The room should also be spacious — a living room is better than a bathroom.
• Avoid lower-quality candles — typically indicative by their price — since those may use conventional waxes or fragrances.
• Extinguish candles that emit heavy black smoke. You can also help prevent this type of smoke by using a candle wick trimmer or scissors to keep wicks trimmed to ¼ inch (0.6 cm).
• When burning scented candles, do so in small doses to avoid headaches or irritation of the respiratory system or eyes.
• Don’t burn candles around children or people who are pregnant or have respiratory conditions.

“It’s important to optimize the quality of the air that you breathe inside your home — where we spend most of our time,” Evans said.

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