Are scented candles bad for you? Are scented candles harmful to cats and dogs? Here’s what the science says

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

Concerns about candle safety are rooted in the chemical reactions that occur when you burn them, as well as the artificial fragrances and dyes that contribute to the various smells you may love.

The candles of primary concern are those made from paraffin, which is a cheap by-product that comes primarily from petroleum refining. Paraffin is the most widely used candle wax worldwide, according to the National Candle Association, the leading trade association representing U.S. candle manufacturers and their suppliers.

However, there are few studies on candle emissions or their potential effects on human health, and research findings are mixed.

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

But the risks can also depend on various factors, including the type and quality of the candle; how often and for how long you burn it; the air flow in the space where you burn it; your state of health; and more.

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

What the science of candles shows

When you burn a paraffin candle, it releases volatile organic compounds, or VOCs — gases that evaporate easily and quickly into the air at room temperature, said Dr. Ariful Haque, medical researcher at Yan’an Hospital affiliated with Kunming Medical University in China. , by e-mail.

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 American Lung Association. Some VOCs are harmful on their own, while others can react with other gases and form pollutants once in the air.

One of the VOCs often emitted by candles is toluene, a colorless vaporized liquid which has a distinctive odor and occurs naturally in crude oil.

Toluene is registered as a toxin with exposure limits set 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 with prolonged exposure, 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 polycyclic aromatic hydrocarbon VOCs, which contain benzene and formaldehyde, another known human carcinogen.

“A good number of studies have assessed candle emissions under controlled conditions as well as in homes and have shown that candle lighting contributes to poor air quality and increases the risk of inhalation 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 can emit toxins even when unlit, according to an April 2015 study which simulated indoor use.

Air concentrations of VOCs found in some candle studies were insignificant compared to levels previously considered unsafe. But other research suggests otherwise – in the April 2015 study, the concentration of formaldehyde emitted by a lit strawberry-scented candle was 2,098 parts per billion, which is well above the range of 0 to 400 parts per billion that different sources consider it acceptable. A lit kiwi and melon scented candle had a total emissions 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 burned emits harmful particles or chemicals, Evans said — so these candles also release VOCs into the air. But paraffin wax is usually more polluting, according to some studies.

The risk of toxic emissions is greater when candles are scented or dyed, which is another reason why paraffin-free candles are not immediately visible. This is because artificial fragrances also have VOCs, including phthalateswhich were related to learning and behavior problemsobesity, impaired reproductive system development and more, Evans said. The unscented candle in the 2015 study also caused worrisome concentrations of toxins, but had the lowest amount compared to its scented counterparts.

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

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

Additionally, there is almost no regulation of 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 “ASTM standards are about fire safety and packaging, not the composition of the candles,” Evans added. “ASTM standards are voluntary and not enforced; products are not checked for compliance.”

There are no regulations requiring full 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 though only a small percentage of the wax is soy, depending on the region and labeling standards, Haque said.

Ways to perfume your home more safely

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

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

Vulnerable people in particular should consider this guide. Those groups include people with breathing problems such as asthma or chronic obstructive pulmonary disease, Farooq said.

All things considered, Evans never burns candles and discourages doing so, she said. Farooq, the pulmonologist, on the other hand, uses candles. She’s just careful about what she buys and where she burns them, she said.

Evans’ advice even applies to candles scented with essential oils — some people think they’re harmless, but that’s not always true because burning them can change their chemical composition, Haque said.

“Some studies find that diffusing essential oils causes breathing problems and interfere with memory and decision making” said Evans. “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 what essential oils can be harmful to children, kitten and dog.

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

Choose candles labeled as 100% soy wax, beeswax or stearin wax when possible.

Make sure the wick is cotton, wood or synthetic and does not contain metal cores, including lead or zinc. (Lead fuses have been banned in several countries, including the United States, Australia, and Denmark.)

If you just can’t resist using scented candles, look for ones with essential oils or candles labeled as phthalate-free.

Avoid painted candles.

Keep the caps on the candles when not in use.

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 cannot disclose individual chemicals, Evans said.

Burn candles in a well-ventilated area to reduce indoor air pollution from soot, VOCs or smoke. Keep the area ventilated after blowing out the candles. The room should also be spacious – a living room is better than a bathroom.

Avoid lower quality candles – usually indicative by price – as they may use wax or conventional 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 inches.

When burning scented candles, do so in small doses to avoid headaches or irritation to the respiratory system or eyes.

Do not burn candles around children or people who are pregnant or have respiratory ailments.

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