Environ. Sci. Technol. 1993, 27, 2736-2744
Sources of Fine Organic Aerosol. 5. Natural Gas Home Appliances Wolfgang F. Rogge,$ Lynn M. Hildemann,?Monica A. Mazurek,* and Glen R. Cass'
Environmental Engineering Science Department and Environmental Quality Laboratory, California Institute of Technology, Pasadena, California 91 125 Bernd R. 1.Simoneit
Environmental Geochemistry Group, College of Oceanic and Atmospheric Sciences, Oregon State University, Corvailis, Oregon 97331 ~~
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Fine particle emissions from the combined exhaust of a vented natural gas-fired residential space heater plus a water heater have been examined using GC/MS techniques. Organic compounds such as n-alkanes, n-alkanoic acids, PAH, oxy-PAH, aza arenes, and thia arenes have been identified in the exhaust emissions. Total fine particle emission rates are fairly low, with 45.8 ng/kJ (f17.4); thus residential natural gas combustion does not add much to the total fine particulate organic carbon (OC) mass emissions to the urban atmosphere (about 0.1 % for the Los *4ngelesarea). At least 22.5 % of the particle mass emitted consists of PAH, oxy-PAH, aza arenes, and thia arenes, and many of these compounds are known or suspected carcinogens or mutagens. If tests of additional units should show comparable emission rates, then residential and small commercial natural gas combustion in the Los Angeles area in 1982 could have contributed amounts of PAH and oxy-PAH to the urban atmosphere that are comparable to that emitted from diesel vehicles and that are about half as much as that released from catalyst-equipped automobiles. Therefore, in spite of its low mass emission rate, natural gas combustion aerosol may be of interest because of its high PAH content. Introduction To evaluate the origin and fate of airborne fine particulate organic matter, the emissionsfrom common urban sources have to be characterized on a molecular level, and their source emission strengths have to be determined. Natural gas is burned in utility and industrial boilers, in industrial process heaters, and by residential and commercial customers. In the Los Angeles area, residential and commercial natural gas combustion is the largest of these uses; here, natural gas is commonly used for space and water heating and for cooking purposes (1). Residential sources contribute to indoor and outdoor fine particle concentrations. Several studies have been conducted in the past to evaluate indoor air quality for particulate and gaseous matter released from natural gas-fired home appliances (2-10). Fine particle emission rates from natural gas-fired home appliances have been measured for unvented and vented space heaters (6-300 ng/kJ), ovens (
