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Published February 15, 1999 | public
Journal Article

Gas Phase C_2−C_(10) Organic Acids Concentrations in the Los Angeles Atmosphere


The atmospheric concentrations of gas-phase C_2−C_(10) monocarboxylic and benzoic acids are reported in samples collected during a severe Los Angeles area photochemical smog episode. Average urban concentrations are 10−50 × greater than concentrations observed at a remote background location, indicating an anthropogenic origin for these compounds. Average urban concentrations during the episode were 16.1 μg m^(-3) (6.6 ppb) for acetic acid and 1.67 μg m^(-3) (0.55 ppb) for propionic acid, with progressively lesser amounts as the carbon chain length of the acids is increased. Spatial and diurnal variations in atmospheric organic acids concentrations point to the importance of both direct emissions from primary sources and formation by photochemical reaction of precursor compounds.

Additional Information

© 1999 American Chemical Society. Received for review June 18, 1998. Revised manuscript received November 11, 1998. Accepted November 13, 1998. We thank the 13 California Institute of Technology graduate students and staff who participated in air monitoring site operations for their assistance; William Bope (South Coast Air Quality Management District) for logistics support in Azusa, Long Beach, and Los Angeles; and Lowell Ashbaugh (California Air Resources Board), Eric Grosjean (DGA Incorporated) and Gervaise McKay (Unisearch Associates) for logistics support in Claremont. This research was supported by the Electric Power Research Institute under Agreement RP3189-03 and by the Caltech Center for Air Quality Analysis.

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October 19, 2023