Secondary Organic Aerosol Formation during the Photo-Oxidation of Toluene: Dependence on Initial Hydrocarbon Concentration

Abstract

Abstract Aerosol formation in toluene–NOx–air–photoirradiation systems was examined in a 6-m3 photochemical reaction chamber. The initial toluene concentration was varied between 2 and 16 ppmv, whereas the initial NOx concentration was kept constant. The aerosol mass concentrations were plotted as a function of the concentration of toluene reacted. The aerosol profiles showed a curved feature at low toluene consumptions, and merged into a single line at longer reaction times. The observed characteristics were explained by assuming condensable products were formed through reactions of ozone with primary toluene photo-oxidation products.