The aim of this paper is to present preliminary results of aerosol modeling over Greater Paris. We briefly describe the parameterizations and the numerical methods related to the general dynamic equation for aerosols: a size resolved aerosol model (SIREAM) has been hosted by the chemistry transport model Polair3D inside the Polyphemus system. Then the results of a simulation over Greater Paris are presented with preliminary comparisons to measured data for aerosols (PM10 and PM2.5) and gases (ozone, NO2) for six months of 2001 (from April to the end of September). A sensitivity analysis is also performed in order to assess the robustness of the model configuration.