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 exami ned using GC/MS techniques. Organic compounds such as n-alkanes, n-alk anoic acids, PAH, oxy-PAH, aza arenes, and thia arenes have been ident ified 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 car bon (OC) mass emissions to the urban atmosphere (about 0.1 % for the L os Angeles area). At least 22.5 % of the particle ass emitted consists of PAH, oxy-PAH, aza arenes, and thia arenes, and many of these compo unds are known or suspected carcinogens or mutagens. If tests of addit ional units should show comparable emission rates, then residential an d small commercial natural gas combustion in the Los Angeles area in 1 982 could have contributed amounts of PAH and oxy-PAH to the urban atm osphere that are comparable to that emitted from diesel vehicles and t hat are about half as much as that released from catalyst-equipped aut omobiles. Therefore, in spite of its low mass emission rate, natural g as combustion aerosol may be of interest because of its high PAH conte nt.