Are scented candles and air fresheners bad for your health?

Air fresheners may release benzene and formaldehyde, and many paraffin candles in a small room add combustion byproducts, though harm at typical use is unproven.

That "fresh linen" candle or plug-in air freshener isn't cleaning your air. It's adding chemicals to it. Many of the most popular home fragrance products release compounds linked to respiratory irritation, hormone disruption, and cancer risk -- all while making you think your home smells "clean."

Paraffin Candles

Most candles sold today are made from paraffin wax, a petroleum byproduct. A single candle in a well-ventilated room may not reach dangerous levels, but burning multiple candles in a small space with poor ventilation is a different story. Scented paraffin candles are the worst combination: you get both the combustion byproducts of the petroleum wax and whatever synthetic fragrance chemicals are mixed in.

Plug-In and Spray Air Fresheners

Plug-in air fresheners heat a liquid fragrance cocktail continuously, releasing a steady stream of volatile organic compounds (VOCs) into your home. Studies have detected formaldehyde, benzene, toluene, and ethylbenzene in emissions from popular air freshener brands¹. Spray fresheners do the same in bursts. They don't eliminate odors -- they mask them by flooding your nose with stronger chemicals, or in some cases, by coating your nasal passages with a film that deadens your sense of smell.

The "Fragrance" Loophole

Look at the ingredients on any scented product -- candle, air freshener, dryer sheet, cleaning spray -- and you'll see "fragrance" or "parfum" listed as a single ingredient. Under current regulations, this one word can represent a blend of dozens to hundreds of individual chemicals that manufacturers are not required to disclose. This is a trade secret protection, not a safety measure. Independent testing has found phthalates (endocrine disruptors linked to reduced pulmonary function²), synthetic musks, and allergens hidden under the "fragrance" umbrella. You literally cannot know what you're breathing.

What you can do

Open windows on opposite sides of your home for five minutes; ventilation is the simplest air freshener.
If you burn candles, choose 100% beeswax or soy with cotton or wood wicks, and avoid burning several in a small, poorly ventilated room.
Skip plug-in and spray fresheners; if you want scent, use an essential-oil diffuser sparingly, especially around pets and children.

Be careful if

'Fragrance' or 'parfum' on a label can hide dozens of undisclosed chemicals, including phthalates linked to reduced lung function².
Essential oils are potent and not risk-free; use them sparingly, especially around pets and children.
Not a substitute for medical care if headaches, congestion or breathing symptoms persist.

Go deeper

How it works What it does in your body, in plain words 1 min

Beeswax candles use one natural wax instead of petroleum paraffin and have a faint honey scent of their own. They are not air cleaners, though. In a lab study of five kinds of pillar candles, every one gave off soot when its flame was disturbed by moving air, and the wax and wick changed how much³. We found no good evidence that beeswax releases negative ions that clean the air. Beeswax candles cost more, but they burn longer; keep them out of drafts.

Soy candles are a middle ground -- cleaner-burning than paraffin, more affordable than beeswax. Look for 100% soy (many "soy" candles are soy-paraffin blends) with cotton or wood wicks and scented only with essential oils.

Essential oil diffusers (ultrasonic or nebulizing) disperse plant-derived aromatic compounds without combustion. Be mindful that essential oils are potent -- use them sparingly, especially around pets and children. They're not risk-free, but they avoid the petroleum byproducts and synthetic fragrance chemicals.

Or just open a window. The simplest air freshener is ventilation. Five minutes of cross-ventilation (opening windows on opposite sides of your home) can dramatically improve indoor air quality without adding anything to the air.

The evidence The studies, what they found, and how much to trust them 1 min · 3 sources

The average person spends about 90% of their time indoors. Indoor air pollution concentrations can be 2 to 5 times higher than outdoor levels, and fragrance products are a major contributor. The chronic, low-level exposure pattern matters -- your body can process occasional exposures, but a plug-in running 24/7 for months creates a continuous chemical burden.

The health effects are real but often misattributed. Headaches, nasal congestion, "allergies," and fatigue that people accept as normal life can be driven by fragrance chemicals in their own homes. People who eliminate synthetic fragrance products from their homes frequently report improvements in these symptoms within weeks.

The phthalate connection is particularly concerning. These plasticizer chemicals are used to make fragrances last longer, and they've been associated with decreased pulmonary function even at common exposure levels². Because they're endocrine disruptors, they may have effects well below what traditional toxicology would predict as a "safe" dose.

Sources

Indoor air quality, ventilation and health symptoms in schools: an analysis of existing information. Daisey JM, Angell WJ, Apte MG. Indoor Air, 2003. PubMed 12608926
Phthalate exposure and pulmonary function. Hoppin JA, Ulmer R, London SJ. Environmental Health Perspectives, 2004. PubMed 15064163
Emissions of soot, PAHs, ultrafine particles, NOx, and other health relevant compounds from stressed burning of candles in indoor air. Andersen C, Omelekhina Y, Rasmussen BB, et al.. Indoor Air, 2021. PubMed 34297865