Indoor air chemistry: cleaning agents, ozone and toxic air contaminants.

When cleaning products and air fresheners are used indoors, occupants are exposed to airborne chemicals, potentially leading to health risks. Indoor air pollutant exposures owing to cleaning product and air freshener use depend on emissions from products, dynamic behavior of chemical species, and human factors. A series of experiments was conducted to investigate volatile organic compound emissions, concentrations, and reactive chemistry associated with the household use of cleaning products and air fresheners. Research focused on two common classes of ingredients in cleaning products and air fresheners: ethylene-based glycol ethers, which are classified as toxic air contaminants, and terpenes, which react rapidly with ozone. A shelf-survey of retail outlets led to the selection of 21 products whose chemical composition was characterized. Among the criteria used to select these products were ready availability through California retail outlets and, for the majority of products, expectation that they contained ethylene-based glycol ethers, terpenes and related compounds, or both. Of the 17 cleaning products characterized, four contained substantial levels of d-limonene (4-25% by mass), three contained terpenoids that are characteristic of pine oil, six contained substantial levels of ethylene-based glycol ethers (0.8-10% by mass), and five contained less than 0.2% of any of the target analytes. Xylene in one product was the only other toxic air contaminant detected. Among the four air fresheners characterized, three contained substantial quantities (9-14% by mass) of terpene hydrocarbon and terpene alcohol constituents, with linalool being the most abundant. Six of the 21 products were investigated in simulated-use experiments in which emissions and concentrations of primary constituents were measured. Cleaning products that contain 2butoxyethanol as an active ingredient produced one-hour-average concentrations of 300 to 2,300 μg/m immediately after simulated typical use in a room-sized chamber. For cleaning products that contain d-limonene as an active ingredient, corresponding levels were 1,000 to 6,000 μg/m. Application of a pine-oil based cleaner produced one-hour-average concentrations of 10-1300 μg/m for terpene hydrocarbons and terpene alcohols. Reactive chemistry was studied by exposing constituents of three products to ozone, both in a bench-scale chamber and during simulated use. Prominent products of the reaction of terpenes with ozone included formaldehyde (a toxic air contaminant), hydroxyl radical, and secondary organic aerosol (a form of fine particulate matter). Incorporating the new experimental data, exposures were estimated for several simulated use scenarios. Under ordinary circumstances, exposures to 2-butoxyethanol, formaldehyde, and secondary organic aerosol are not expected to be as high as guideline values solely as a result of cleaning product or air freshener use. However, ordinary use could lead to exposure levels of similar magnitude as guideline values. Scenario model results suggest that exposure levels could exceed guideline values under exceptional yet plausible conditions, such as cleaning a large surface area in a small room. The results of this study provide important information for understanding the inhalation exposures to certain air pollutants that can result from the use of common household products.