Physical and chemical properties of urban aerosols in São Paulo, Brazil: links between composition and size distribution of submicron particles

Abstract. In this work, the relationships between size and composition of submicron particles (PM1) were analyzed at an urban site in Metropolitan Area São Paulo (MASP), a megacity with about 21 million inhabitants. The measurements carried out from 20 December 2016 to 15 March 2017. chemical was measured Aerodyne Aerosol Chemical Speciation Monitor distribution TSI Scanning Mobility Particle Sizer 3082. PM1 mass concentrations MASP had average concentration 11.4 µg m−3. Organic aerosol (OA) dominated (56 %), followed by sulfate (15 %) equivalent black carbon (eBC, 13 %). Four OA classes identified using positive matrix factorization: oxygenated organic (OOA, 40 % OA), biomass burning (BBOA, two hydrocarbon-like components (a typical HOA related vehicular emissions (16 second (21 representing mix anthropogenic sources). number averaged 12 100±6900 cm−3, Aitken mode. accumulation mode increased under relatively high-PM1 conditions, suggesting enhancement secondary (SOA) production. Conversely, contribution nucleation-mode less dependent on levels, consistent emissions. relationship modes assessed multilinear regression (MLR) models. Secondary inorganic aerosols partitioned modes, condensation particle growth processes. Submicron loading mostly associated highly oxidized OOA also traffic-related To authors' knowledge, is first work that uses MLR methodology estimate different modes. size-dependent PM provides innovative information properties both primary aerosols, as well complex environment. results emphasize relevance air quality highlight key role processes ambient region since 56 attributed SOA aerosol.