In situ organic aerosol formation during a smog episode: Estimated production and chemical functionality

Estimates are presented of the amount and chemical functionality of the organic aerosol formed in situ in the atmosphere during a smog episode. Input parameters used in these estimates include speciated volatile organic carbon (VOC) emission rates, their rates of reaction, products including condensible species, and the nature and yields of these condensible species. The functional groups predicted to form and the estimated amount produced during a typical smog episode are carbonyls, aliphatic nitrates, aliphatic carboxylic acids, phenols and nitro aromatics (670, 240, 1360, 3120 and 3120 kg day−1, respectively, using southern California VOC emission data as an example of application). Similarities and differences between calculated organic aerosol composition and experimental observations (two data sets obtained using different methods) are discussed in terms of organic aerosol formation pathways and sampling artifact for the following functional groups: aliphatic carboxylic acids, carbonyls, aliphatic nitrates, phenols, aromatic acids, nitro aromatics, amides and esters.