were forecasted to reach $7.3 billion by 2010. Air fresheners introduce fragrance into the air of interior spaces either as droplets which transition to vapor, or as the molecules of fragrance ingredients directly evaporating from a source. Fragrance diffuses into the air to mask other odors or to introduce a specific odor. Ingredients In addition to the adsorbents, oxidizers, surfactants, and disinfectants listed above, ingredients in air fresheners can include fragrances, aerosol propellants, preservatives, and solvents such as mineral oil or 2-butoxyethanol and other glycol ethers. As fragrances, air freshener preparations often include terpenes such as limonene. A report issued in 2005 by the Bureau Européen des Unions de Consommateurs (BEUC) found that many air freshener products emit allergens and toxic air pollutants including benzene, formaldehyde, terpenes, styrene, phthalate esters, and toluene. In 2020 air fresheners (as well as cleaning solutions and products used to clean cars) will need to list any of their ingredients which are on California's list of 2,300 harmful chemicals, based on a California law passed in 2017. A California study in 2006 found that the prominent products of the reaction of terpenes found in air fresheners with ozone included formaldehyde, hydroxyl radical, and secondary ultrafine particles. It is not clear if manufacturers will need to list such chemicals which are not ingredients, but form when the air freshener is placed in the air. Toxicity Many air fresheners employ carcinogens, volatile organic compounds and known toxins such as phthalate esters in their formulas. A Natural Resources Defense Council (NRDC) study of 13 common household air fresheners found that most of the surveyed products contain chemicals that can aggravate asthma and affect reproductive development. The NRDC called for more rigorous supervision of the manufacturers and their products, which are widely assumed to be safe: 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, along with the Sierra Club, Alliance for Healthy Homes, and the National Center for Healthy Housing, the NRDC filed a petition with the U.S. Environmental Protection Agency and the Consumer Product Safety Commission to report the findings. The University of Bristol's Avon Longitudinal Study of