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.