ARB Research Seminar
This page updated July 24, 2013
Indoor Air Chemistry: Cleaning Products, Ozone, and Toxic Air Contaminants
Brett Singer, Ph. D., Lawrence Berkeley National Laboratory
October 17, 2006
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA
When cleaning products and air fresheners are used indoors, occupants are exposed to airborne chemicals, potentially leading to health risks. These exposures 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 these products: 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. Products were selected based on widespread availability in California retail outlets and, for the majority of products, expectation that they contained ethylene-based glycol ethers, and/or terpenes. Of the 17 cleaning products characterized, four contained substantial levels of d-limonene (4-25% by mass), three contained terpenoids 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. Among the four air fresheners characterized, three contained substantial quantities (9-14% by mass) of terpenes (hydrocarbons and alcohols), 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 2-butoxyethanol as an active ingredient produced one-hour-average concentrations of 300 to 2,300 µg/m3 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/m3. Application of a pine-oil based cleaner produced one-hour-average concentrations of 10-1300 µg/m3 for terpenes.
Reactive chemistry was studied by exposing constituents of three products to ozone, both in a bench-scale chamber and during simulated use. These reactions result in the formation of formaldehyde (a toxic air contaminant), hydroxyl radical, and secondary organic aerosol, which is initially formed as ultrafine particles (less than 100 nanometers in diameter). The experimental data was used to estimate exposures associated with typical product use. Ordinary scenarios of cleaning product and air freshener use can lead to exposures to 2-butoxyethanol, formaldehyde, and secondary organic aerosol that are of similar magnitude to guideline levels, based solely on product emissions and not considering other sources. 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.
Brett Singer, Ph.D., is a Staff Scientist in the Atmospheric Sciences and Indoor Environment Departments of the Environmental Energy Technologies Division of Lawrence Berkeley National Laboratory. Dr. Singer works broadly in the field of air quality research, with specific expertise in the measurement of pollutant emissions, characterization of pollutant dynamics in real and simulated indoor environments, emission inventory development, and air pollutant exposure analysis. Dr. Singer earned a Ph.D. from the U.C. Berkeley Civil Engineering Department's Environmental Engineering Group in 1998. His dissertation research focused on the development of new approaches to quantifying on-road motor vehicle emissions.