At the Royal Meteorological Institute of Belgium we use the chemical transport model (CTM) CHIMERE. In a first phase it has been coupled to meteo fields from ECMWF. The emission database used is EMEP. The simulation domain covers Western Europe with a spatial resolution of 50 km. RMI also runs the Limited Area NWP model ALADIN operationally four times a day at a spatial resolution of 7 km. The meteorological fields from ALADIN have been used to apply a one way nesting to the CTM model running at a spatial resolution of 7 km on a domain of about 680 × 680 km2 covering Belgium and The Netherlands. The emission database used for this high resolution is the TNO/GEMS emission database. We present the first results of this coupling for ozone and PM10 for two different episodes. Also the influence of running ALADIN and its updated version ALARO with improved physical parameterizations will be investigated.