Is Air Freshener Bad for You? The Health Risks

Air fresheners pose genuine health risks, particularly for people with asthma, infants, and pets. The chemicals they release into indoor air include volatile organic compounds (VOCs) linked to respiratory irritation, headaches, and hormonal disruption, and those chemicals can react with ordinary indoor ozone to generate secondary pollutants like formaldehyde and fine particulate matter. The fact that these products are so common and so pleasant-smelling makes the risks easy to underestimate.

What Air Fresheners Actually Release

Regardless of their form, air fresheners work by releasing volatile chemicals into the air. These include terpenes like limonene (the compound behind citrus scents), linalool, dihydromyrcenol, and pinene, along with solvents like ethanol and glycol ethers.¹ Chamber studies have measured high emission rates of these compounds: in one set of German experiments, ethanol emissions topped 35,000 micrograms per unit per hour, with limonene exceeding 9,000 and linalool close to 3,000. A screening study of both plug-in home fresheners and hanging car fresheners found VOCs that had nothing to do with fragrance and that carry potential health risks.²

All types of air fresheners, whether sprays, gels, solids, plug-ins, oils, wick diffusers, or scented candles, emit high concentrations of VOCs. Research comparing different delivery mechanisms suggests that the fragrance formulation matters more than the product type. A spray and a gel using the same scent blend will release a similar cocktail of chemicals. This means switching from a spray to a reed diffuser does not necessarily reduce your exposure if the underlying fragrance recipe is the same.

The Hidden Reactions Happening in Your Air

The chemicals that come directly out of an air freshener are only part of the story. When terpenes like limonene and pinene meet ozone, which is present at low levels in most indoor spaces from outdoor air infiltration and some electronics, they react to produce secondary pollutants. These include formaldehyde, ultrafine particles, and secondary organic aerosol.³ A U.S. Environmental Protection Agency chamber study confirmed this process: a single pine-scented plug-in freshener, when combined with ozone at realistic indoor levels, generated measurable reaction products on top of the ten or more VOCs the freshener was already emitting.⁴

This matters because formaldehyde is a known human carcinogen, and fine particulate matter is linked to cardiovascular and respiratory disease. Research has found that the formaldehyde and particle levels generated by air freshener–ozone reactions can approach or exceed health-based exposure guidelines under some indoor conditions.⁵ Under worst-case but still realistic scenarios (a small room, poor ventilation, continuous product use), one-hour formaldehyde concentrations from sprays and diffusers can reach roughly 370 micrograms per cubic meter, and fine particle concentrations can exceed 100 micrograms per cubic meter.⁶ For context, the World Health Organization’s guideline for short-term formaldehyde exposure is 100 micrograms per cubic meter, so these peak values can overshoot that by a wide margin.

Respiratory Effects and Asthma

The respiratory connection is the best-documented health concern. Air fresheners have been associated with migraine headaches, breathing difficulties, mucosal symptoms, and asthma attacks.⁷ For people with asthma, the picture is considerably worse. A survey-based study found that about 41% of asthmatics reported health problems from air fresheners and deodorizers, compared to about 13% of non-asthmatics. Among the asthmatics who were affected, over half reported respiratory problems, roughly 39% reported actual asthma attacks, and about 37% reported migraine headaches.⁸

Those numbers come from self-reported data, so they reflect what people notice and attribute to air fresheners rather than controlled clinical exposures. Still, the pattern is consistent across studies and large enough that the association is taken seriously by researchers. The terpenes and aldehydes in air fresheners are known sensory irritants, and their reaction products (formaldehyde, fine particles) are established respiratory hazards. The mechanism is plausible and the epidemiology lines up with it.

Pregnant Women, Infants, and Young Children

Some of the more concerning findings involve prenatal and early-life exposure. A study tracking household product use during pregnancy found that using air fresheners was associated with a roughly 29% higher odds of lower respiratory tract infections in the child during early life. That association held even when the air fresheners were used only during pregnancy and not after birth, suggesting the prenatal exposure itself played a role.⁹

Separate research on mothers and infants in the home environment found that higher total VOC levels were associated with air freshener use, and that infant diarrhea and earache were significantly associated with that use. Mothers who used air fresheners also reported more headaches eight months after birth, and maternal depression was significantly linked to air freshener use as well.¹⁰ These are observational findings, and households that use more air fresheners may differ in other ways too. But the consistency of the direction, with freshener use linked to worse outcomes across different symptom types and different populations, is what makes researchers wary.

For families with young children, the practical takeaway is straightforward: infants breathe faster than adults relative to their body size, spend nearly all their time indoors, and have immature airways. They get a proportionally higher dose of whatever is in the air, and they are less equipped to handle it.

Endocrine-Disrupting Chemicals in Fragranced Products

Beyond the respiratory and irritant effects, some air freshener ingredients raise hormonal concerns. Phthalates, a family of chemicals used as solvents and plasticizers in fragrance formulations, show up at high concentrations in certain fragranced products. One analysis of consumer products found that diethyl phthalate (DEP), a common fragrance solvent, was present at 8,000 micrograms per gram in a car air freshener, second only to concentrated perfume.¹¹ DEP itself is not generally classified as endocrine-active, but other phthalates detected in consumer products are identified as anti-androgenic endocrine disruptors in mammalian models. The fragrance mixture in any given air freshener could contain several phthalates, and the consumer has no easy way to find out which ones.

This connects to one of the more frustrating aspects of air freshener regulation: the word “fragrance” on a product label can represent dozens of individual chemicals, and manufacturers are not required to disclose them.

Why “Natural” and “Green” Labels Do Not Help Much

If your instinct is to switch to a product labeled “natural,” “organic,” or “green,” the evidence suggests that won’t solve the problem. A study comparing VOC emissions from regular car air fresheners to those marketed as natural or green found no significant difference in the emissions of hazardous compounds.¹² This finding makes sense once you understand the chemistry. Limonene is a “natural” compound, derived from citrus peel, and it is one of the most abundant VOCs air fresheners emit. It is also one of the most reactive with ozone, generating formaldehyde and particles regardless of whether it came from a synthetic lab or an organic orange grove. The source of the chemical does not change its behavior once it is airborne in your living room.

Essential oil diffusers fall into the same trap. Pure lavender oil, pure eucalyptus oil, and pure lemon oil all emit terpenes and other VOCs. Their reaction with indoor ozone will produce the same secondary pollutants. Marketing language has outpaced the chemistry here, and consumers who believe they are choosing a safer option may be getting the same exposure profile under a friendlier label.

The Labeling Gap

In the United States, manufacturers of consumer products are not required to disclose all ingredients to consumers. Fragrance ingredients, specifically, are exempt from disclosure in any product. Depending on the product category, the word “fragrance” may or may not even need to appear on the label.¹³ This means that even a motivated consumer reading the label carefully cannot determine what chemicals an air freshener will release into their home. The fragrance industry self-regulates through its own trade association, which sets safety standards but does not require public ingredient lists.

This is one area where the evidence is clear but the policy lags. Researchers can measure what these products emit in chamber studies, but the average buyer has no access to that information at the point of purchase. A product might list “fragrance” as a single ingredient while actually containing 20 or more individual chemicals, some of them potentially hazardous and some of them inert. Without disclosure, you are trusting the manufacturer’s internal safety assessment, which may or may not account for secondary pollutant formation in real indoor conditions.

People with Chemical Sensitivities

A subset of the population reacts more severely to fragranced products than the general public. Among people with multiple chemical sensitivities (MCS), about 86% report health problems from fragranced consumer products. The most common triggers specifically include air fresheners and deodorizers, reported by about 68% of those with MCS. The symptoms go beyond respiratory issues to include migraine headaches (about 47%), skin problems (about 38%), and neurological symptoms.¹⁴

MCS remains a controversial diagnosis in some medical circles, with debate about whether it represents a toxicological response, an amplified sensory processing issue, or something else entirely. But the symptom burden is real and measurable regardless of the underlying mechanism. For people in this group, air fresheners in shared spaces like offices, stores, and public restrooms are not a minor nuisance but a genuine health barrier. Some workplaces and healthcare facilities have adopted fragrance-free policies in response, though adoption is uneven.

What About Pets

Cats and birds are especially vulnerable. Cats lack certain liver enzymes that help metabolize some of the compounds found in essential oils and fragranced products. A case series documented severe oral and tongue ulceration in cats exposed to liquid potpourri oil, along with fever, rapid breathing, drooling, and lethargy. The prognosis was good with supportive veterinary care, but the injuries were serious enough to require it.¹⁵

Beyond acute poisoning events, chronic low-level exposure may also matter. Research using silicone tags worn by cats found that higher concentrations of a flame retardant chemical (TDCIPP) were associated with air freshener use in the home. TDCIPP exposure has separately been linked to feline hyperthyroidism, one of the most common endocrine disorders in older cats.¹⁶ That finding does not prove air fresheners cause hyperthyroidism, but it does suggest that these products contribute to a broader chemical exposure mix that may be relevant to pet health. Birds, with their extremely efficient respiratory systems, are even more sensitive to airborne chemicals, and veterinarians commonly advise keeping birds away from all scented products.

Why People Keep Using Them Anyway

Given all this, you might wonder why air fresheners remain enormously popular. A framework proposed by consumer researchers identifies three layers of benefit driving that popularity: functional benefits (covering up bad smells), in-use experience benefits (the feeling that a space is clean and pleasant), and emotional benefits (mood improvement, comfort, nostalgia).¹⁷ Air fresheners are tapping into something deeper than odor management. A particular scent can make a home feel welcoming, trigger pleasant memories, or signal cleanliness to a visitor. These psychological rewards are immediate and tangible, while the health risks are invisible, delayed, and probabilistic. That asymmetry is powerful.

It also explains why simply telling people “air fresheners are bad” rarely changes behavior. The benefits are felt every time the product is used; the harms are statistical and may never manifest in any one individual. This is similar to other indoor air quality challenges: people will invest in a good-smelling candle before they will invest in better ventilation, even though the ventilation would do more for their health.

Reducing Your Exposure Without Going Scent-Free

If you want to reduce the risk without giving up indoor scent entirely, ventilation is the single most effective tool. Opening windows or running exhaust fans while using any scented product dramatically lowers the concentration of both primary VOCs and secondary pollutants. The chemistry of ozone reactions depends on concentration: fewer terpene molecules meeting fewer ozone molecules means fewer reaction products. A well-ventilated room will never accumulate the formaldehyde and particle levels seen in sealed chamber studies.

Other practical steps include using scented products intermittently rather than continuously (a plug-in running 24 hours produces far more cumulative exposure than one running for 30 minutes before guests arrive), choosing unscented alternatives for routine cleaning, and addressing bad odors at their source rather than covering them with fragrance. Baking soda, activated charcoal, and simply taking out the trash are not glamorous, but they eliminate odors rather than layering new chemicals on top of them.

If you have asthma, infants, cats, or birds in the household, the calculus tilts more strongly toward avoidance. The evidence of harm is more direct and more severe for these groups, and the benefit of a pleasant scent does not offset a trip to the emergency room or the veterinarian. For the general healthy adult, the risks from occasional air freshener use are modest and probabilistic, more comparable to other everyday indoor air quality compromises than to an acute poison. But “modest” is not “zero,” and the cumulative effect of continuous use in a poorly ventilated space can push exposures into ranges that researchers flag as concerning.