According to the U.S. Environmental Protection Agency (EPA), most store-bought air fresheners consist of formaldehyde, petrochemicals, p-dichlorobenzene and aerosol pollutants [source: EPA]. The agency's "Indoor Guide to Air Quality" also notes that air fresheners "release pollutants more or less continuously" [source: EPA].
The University of California at Berkeley performed a study on air fresheners and household cleaners in 2006 that discovered ethylene-based glycol ethers, classified by the EPA as hazardous air pollutants [source: ScienceDaily]. It also found the presence of terpenes, which are chemicals often derived from citrus oils that are not inherently dangerous, but react with ozone to form formaldehyde [source: UC Berkeley]. While these conclusions may seem like cause for alarm, the study also reported that health-related issues would apply mostly to professional house cleaners or janitors who are exposed to high levels of the products [source: ScienceDaily].
One of the active ingredients in mothballs, 1,4 dichlorobenzene, also is present in many air fresheners. The EPA's air quality guide lists this chemical as toxic since its vapors can affect respiratory function. Likewise, the U.S. National Institute of Health Sciences reported that the chemicals in air fresheners can reduce lung capacity and may hasten respiratory diseases [source: ScienceDaily].
Along those same lines, there appears to be a correlation between air fresheners and asthma problems. A University of Washington study on chemical hypersensitivity polled people about their reactions to air fresheners. Around a third of the participants with asthma said air fresheners will aggravate their condition, and 40 percent reacted negatively to scented products in general [source: Caress and Steinemann].
This could be connected to that combination of certain chemicals in air fresheners and ozone that form formaldehyde [source: Caress and Steinemann]. Why so many mentions of formaldehyde? The gas can lead to impaired breathing in people and can cause cancer in animals [source: EPA].
Nevertheless, the EPA has not advised against buying air fresheners, but rather that people should exercise care with usage. That's because many of the chemical-related studies simulated higher levels of indoor ozone and air freshener consumption than normally occurs in homes. Also, some companies now sell "greener" air fresheners for consumers who are concerned about the health effects with lowered levels of pollutants.
If you still aren't satisfied with your air freshener options, you can take the natural route. Proper ventilation, along with baking soda, coffee grounds or lemon peels (try grinding them up in your disposal) can all disperse and eliminate peevish odors.
For more information about air fresheners, follow your nose to the links on the next page.