The Air and Soil Pollution Laboratory (LPAS) at the EPFL, Switzerland has a strong competence in air quality modelling and model development. New air quality modeling tools are continually developed for specific simulations: 1) FVM: a mesoscale wind model adapted for alpine complex terrain and urban areas, and 2) TAPOM: a pollutant transport model designed to study the coupling between different gas phase chemical mechanism, the aerosol formation and the solar radiation (see Project development ). The models are regularly validated on various sites using the measurements obtained during different intensive campaigns. After the validation step the models are applied to predict the impact of abatement strategies, to study the effect of different mechanisms (gas phase chemical mechanisms, aerosol formation mechanisms) on the photo-oxidant formation or to estimate the model uncertainties. Studies over Madrid, Grenoble, Milan, the Swiss plateau, Geneva and Athens have been conducted. Further studies in Mexico City, Bogota and Ho Chi Minh City are underway.