27. Air Quality Modelling and Source Apportionment Studies for Aerosols in Switzerland

We modelled the air quality in Switzerland for summer and winter periods in 2006 using the CAMx model with the focus on aerosols. The contributions of various source regions to aerosol concentrations at receptor sites were investigated using the Particulate Matter Source Apportionment Technology (PSAT) tool of CAMx. The source regions were defined as Switzerland, surrounding countries and other countries in Europe. Organic aerosols (OA) and particulate nitrate (PNO₃) are the main components of winter aerosols in the modeled domain. In summer, organic aerosols dominate the aerosol composition and they are mainly secondary. In general more than 50% of PM2.5 was predicted to come from Swiss sources except for a few sites at the border regions. Primary particles originate mostly from local sources in both seasons, except at Basel where significant contribution from France and Germany was predicted. In the south, Italy is the main contributor to aerosols. On the other hand, about half of the secondary aerosols originate from Germany and France for receptors in the north and from Italy for receptors in the south.