They work in one of five ways:
"The study assessed scented sprays, gels, and plug-in air fresheners. Independent lab testing confirmed the presence of phthalates, or hormone-disrupting chemicals that may pose a particular health risk to babies and young children, in 12 of the 14 products—including those marked 'all natural.' None of the products had these chemicals listed on their labels."
On September 19, 2007, the NRDC, along with the Sierra Club, Alliance for Healthy Homes, and the National Center for Healthy Housing filed a petition with the U.S. Environmental Protection Agency and the Consumer Product Safety Commission to report the findings.
Exposure to volatile organic compounds through frequent use of air fresheners and other aerosols in the home was found to correlate with increased earaches and diarrhea in infants, and with increased depression in their mothers in a large study reported by the University of Bristol in the UK in 2003.
In 2008, Anne Steinemann of the University of Washington published a study of top-selling laundry products and air fresheners in the journal Environmental Impact Assessment Review. She found that all six products tested gave off at least one chemical regulated as toxic or hazardous under federal laws, but none of those chemicals was listed on the product labels. Chemicals included acetone, the active ingredient in paint thinner and nail-polish remover; limonene, a molecule with a citrus scent; and acetaldehyde, chloromethane and 1,4-dioxane. A plug-in air freshener contained more than 20 different volatile organic compounds. Of these, seven are regulated as toxic or hazardous under federal laws.