| Polar organic compounds are quantified in fine particulate matter emitted from major urban air pollution sources. Fine particulate matter emissions from meat cooking, hardwood and softwood combustion, motor vehicle exhaust, and cigarette smoking, along with leaf particulate abrasion products, tire dust, brake dust, and paved road dust, are converted to trimethylsilyl derivatives and analyzed by gas chromatography/mass spectrometry. Silylation enables or improves the quantification of a number of compounds, including cholesterol and other sterols, monoglycerides, levoglucosan and related sugar anhydrides, normal alkanols, triterpenoids, and compounds derived from wood lignin, which may be suitable tracers for specific emission sources of fine particulate matter. In addition, gas phase formic and acetic acids concentrations are reported over an 8-month period at 9 sites in the Los Angeles air basin. A comparison of these concentration profiles with concentrations of other pollutants and with meteorological variables shows that both direct emissions and atmospheric chemical formation contribute to observed levels of formic and acetic acids. Finally, longer chain gas phase organic acids (from C2 up to C10) are measured during a severe photochemical smog episode in the Los Angeles area. |
