Neither candles nor air fresheners are truly “clean” when it comes to indoor air quality, but the two products pose different risks, and the gap between them depends heavily on which type of candle and which type of air freshener you’re comparing. A cheap paraffin candle and a plug-in air freshener can both release harmful chemicals into your home. A beeswax candle with a cotton wick, on the other hand, produces virtually none of the concerning compounds found in either category.
What Air Fresheners Release Into Your Home
Air fresheners, whether sprays, plug-ins, or gel types, are more chemically complex than most people realize. A study published in Environmental Health Perspectives found that scented consumer products emit more than 100 different volatile organic compounds. The average product released 17 VOCs, and each one emitted between 1 and 8 chemicals classified as toxic or hazardous under federal law. Close to half of the products tested generated at least one carcinogenic air pollutant, including formaldehyde, acetaldehyde, and methylene chloride.
Perhaps the most unsettling finding: of the 133 VOCs detected across the products, only ethanol appeared on any product label. The vast majority of these chemicals were completely undisclosed. So even if you read the label carefully, you’d have almost no idea what you were breathing in.
Air fresheners also create a secondary problem that candles don’t. Many contain terpenes, the compounds responsible for citrus and pine scents. These terpenes react with ozone already present in your indoor air, and that reaction produces new pollutants. Research from Lawrence Berkeley National Laboratory found that when terpene-containing products mix with ozone, they generate formaldehyde as the predominant byproduct, along with acetaldehyde and acetone. The reaction also triggers the formation of ultrafine particles, which are small enough to penetrate deep into lung tissue. In other words, the air freshener keeps producing pollutants even after you spray it.
What Candles Release Depends on the Wax
Not all candles are created equal, and the wax type is the single biggest factor in how much pollution they produce.
Paraffin wax, the most common and cheapest option, is a petroleum byproduct. When it burns, it releases toluene and benzene, both known toxic compounds. It also generates significant black soot made of PM2.5 fine particulate matter, the same category of particles linked to respiratory and cardiovascular problems. Under normal conditions, EPA testing found that candle PM2.5 emission rates range from about 41 to 521 micrograms per hour per wick. But when a paraffin candle soots excessively (from a long or untrimmed wick, for example), concentrations can spike to nearly 1,000 micrograms per cubic meter, which is well above levels considered safe for indoor air.
Soy wax performs significantly better. A 2009 study from South Carolina State University found that soy candles do not release the benzene and toluene emissions associated with paraffin. They also produce roughly 90% less soot. Beeswax is the cleanest option of the three: it burns with near-zero soot and no detectable toxic VOC emissions.
Quick Comparison by Wax Type
- Paraffin: High VOC emissions (benzene, toluene), heavy soot, PM2.5 particulates
- Soy: No benzene or toluene detected, 90% less soot than paraffin
- Beeswax: Virtually no soot, no toxic VOC emissions
The Fragrance Itself Is a Shared Risk
Whether it comes from a candle or a plug-in, synthetic fragrance is its own concern. Fragrance allergy affects roughly 1% to 3% of the general population, and among people who get patch-tested for skin reactions, 5% to 11% react to common fragrance chemicals. The allergens are the same compounds used in both scented candles and air fresheners: limonene, linalool, and various synthetic musks. If you’re sensitive, switching from an air freshener to a heavily scented candle won’t necessarily solve the problem. Unscented beeswax or soy candles sidestep this issue entirely.
Fire Risk Sets Candles Apart
One clear disadvantage candles have over air fresheners is the open flame. U.S. fire departments respond to an average of 5,894 home fires per year caused by candles, based on data from 2020 to 2024. That’s a real and preventable risk. Air fresheners, while chemically concerning, don’t start house fires. If you use candles, keeping wicks trimmed to a quarter inch, placing them on stable surfaces away from curtains and pets, and never leaving them unattended meaningfully reduces both fire risk and soot production.
So Which Is Actually Better?
If you’re comparing a paraffin candle to a plug-in air freshener, neither one wins. Both release toxic VOCs, and the paraffin candle adds soot and fire risk on top. A plug-in adds the ozone-terpene reaction problem, generating new pollutants hours after use.
If you’re comparing a soy or beeswax candle to any type of air freshener, the candle is the better choice for air quality. Beeswax in particular produces essentially no toxic emissions, no soot, and no secondary chemical reactions. The only tradeoff is the fire hazard, which proper candle habits can minimize.
For the cleanest indoor air, your best options in order:
- Unscented beeswax candles: No toxic VOCs, no soot, no synthetic fragrance allergens
- Soy candles with natural fragrance: Very low emissions, minimal soot
- Essential oil diffusers (no heat): No combustion byproducts, though terpenes can still react with indoor ozone
- Scented paraffin candles or air fresheners: Both introduce significant VOCs and particulates into your home
The simplest upgrade most people can make is switching from paraffin to soy or beeswax. That single change eliminates benzene and toluene exposure and cuts soot by 90% or more, giving you the ambiance of a candle without the air quality penalty that puts cheap candles in the same category as plug-in fresheners.