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A Breath of Fresh Air? Hardly.

Air fresheners do not freshen air. They just inject an array of pleasant-smelling chemicals into the air that can mask unpleasant smells. But this can come with some unpleasant health consequences.

The Centers for Disease Control and Prevention (CDC), headquartered in Atlanta, is often in the news because of its mandate to protect the health of the public. These days it is almost impossible to have a conversation about Covid-19 without the name of CDC popping up. Of course, the organization deals with much more than illness due to viral infections. The effect of fragrances on health is also in its domain. Recognizing that some individuals can suffer adverse reactions to scents, in 2009 CDC instituted a policy in all its buildings: “Scented and fragranced products are prohibited at all times in all interior space owned, rented or leased by CDC, including incense, candles, electric fragrance-emitting devices, air fresheners and urinal blocks.” 

CDC does not act without evidence, and indeed there is incontrovertible proof that exposure to fragrances from cleaning products, cosmetics and air fresheners can trigger problems that range from headaches and gastrointestinal problems to skin irritation and asthmatic attacks. About 20% of the general population and 30% of asthmatics report being affected to some degree with many remarking that they are even reluctant to enter a public restroom because of the use of scented cleaning products. A nuance with fragrances is that sensitivity can increase with repeated exposure. Individuals who have no previous history of a reaction can eventually become intolerant as their immune system becomes sensitized. 

Exactly what chemical causes an adverse reaction is virtually impossible to determine given that fragrances added to consumer products are complex mixtures with over a hundred components having been identified. Some of these are extracts of plants, others are synthesized in a lab, but their origin has no bearing on their ability to irritate or provoke an allergic reaction. Geraniol, limonene, coumerol and linalool are all plant products but are recognized allergens. Some fragrances incorporate phthalates, compounds that allow the scent to linger longer. The issue with phthalates is that they have been classified as “endocrine disruptors,” meaning that they can interfere with hormonal activity. However,  it is unlikely that the amounts used in fragrances can have a significant effect. 

Claims of “green,” “organic,” “non-toxic,” and “natural” made on behalf of some air fresheners are meaningless. These are no less as likely to cause problems in sensitive people and some have been found to contain undeclared phthalates. A further issue with scented products is that once released into the air, their components can engage in chemical reactions, often prompted by exposure to light or ozone, itself a pollutant present in air. For example, formaldehyde and acetaldehyde, both known carcinogens, may not be originally present in a fragrance but can form from the decomposition of other components, be they natural or synthetic. An added problem is that the spray dispersed from an aerosol can contains ultrafine droplets or particles that can be inhaled and cause respiratory problems regardless of their composition. 

Fragrances from scented products and air fresheners are not the only concern when it comes to indoor air. Chemicals from paints, furniture, fabrics, particle board and vinyl tiles can “outgas.” And let’s not forget about pollen, cockroach particles, dust mites, molds, bacteria, viruses and combustion products such as carbon monoxide and oxides of nitrogen released by gas stoves, candles and fireplaces. All of this adds up to quite a complex chemical brew! To what extent exposure to all these pollutants affects our health is difficult to determine, as is the role played by air fresheners. It is a good bet, though, that they are not doing us good. Given that we spend about 90% of our life indoors. The possible effects of air fresheners on health cannot be swept under the carpet. And if that carpet is new, well, you don’t even want to know what volatile compounds it and its padding can release.  

“Deodorizers” are distinct products from air fresheners although some fresheners wrongly advertise themselves as deodorizers. Deodorizers actually eliminate smells instead of masking them in one of four ways. Fragrant molecules can be adsorbed to the surface of a substance such as charcoal or a mineral called zeolite. These can be introduced into a filter through which air passes propelled by a fan or can just be left out in open containers placed around a room. Another method is to use a spray containing cyclodextrin, a donut shaped molecule that can trap smaller molecules in its cavity and prevent them from binding to receptors in the olfactory system. Sprays containing droplets of propylene glycol or triethylene glycol can also work since these are good solvents for many organic compounds found in fragrances. The droplets then fall to the ground ,taking the scents with them.  

But by far the best way to eliminate smells is through chemical reaction with ozone. This is a strong oxidizing agent capable of destroying molecules by breaking bonds that hold their atoms together. Ozone can be produced by a device designed to pass an electric current through oxygen. Such ozone generators can be rented, as is commonly done to rid a house of smoke after a fire. But ozone is a toxic gas so generators can only be run when people are not around. It also attacks rubber, so if an ozone generator is being used, it is best not to leave condoms lying around. 


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