Sources of Fine Organic Aerosol. 5. Natural Gas Home Appliances

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 (±17.4); 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 Angeles area). 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.