The characteristics of ambient aerosol during two seasons (spring/autumn) and at two locations (suburban/urban) in Rome were investigated. We distinguished regionally advected and locally produced organic aerosols, including from cooking, traffic and biomass burning, but also from locally emitted cigarette smoke, for which we propose a new marker peak for identification in aerosol mass spectra. The impact of Saharan dust advection events on local aerosol concentration was studied.