The ARB asked Nazaroff and his team to focus their work in two areas: an investigation of toxic air contaminants in household cleaning products and air fresheners, especially a class of chemicals known as ethylene-based glycol ethers; and an examination of the chemistry that occurs when such products are used indoors ?in particular, products that contain a reactive group of chemicals called terpenes.
Ethylene-based glycol ethers are common, water-soluble solvents used in a variety of cleaning agents, latex paints and other products. They are classified as hazardous air pollutants under the U.S. Environmental Protection Agency's 1990 Clean Air Act Amendments and as toxic air contaminants by California's Air Resources Board. Their toxicity varies with their chemical structure.
Terpenes are a class of chemicals found in pine, lemon and orange oils that are used in many consumer products either as solvents or to provide a distinctive scent. Although terpenes themselves are not considered toxic, some recent studies have shown that they may react with ozone to produce a number of toxic compounds. (The primary constituent of smog, ozone enters the indoor environment from infiltration of outdoor air, but is also produced indoors by some office machines such as copiers or printers, and by some devices marketed as "air purifiers" that purposely emit ozone into the indoor environment.)
The research team's first task was to determine which household products contain terpenes and glycol ethers, and in what quantities. It compiled a list of the household cleaners and air fresheners available at any of five chain retail outlets in Northern California, then examined the labels and advertising claims (e.
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Source:University of California - Berkeley