The main objective of this project is to assess and reduce uncertainty on air quality model results throughout the applications of the EURAD modelling system over mainland Portugal and to improve the scientifically sounding knowledge of dynamics (transport, diffusion and chemical transformations) of the atmospheric pollutants. A special attention will be devoted to particulate matter and ozone which are of major concern for the Portuguese Government due to the high number of concentration exceedances per year. This project also intends to explain and characterise the phenomena that drives high values for these pollutants in order to account them on the Plans and Programs designed for minimising concentration values. During the development of this project, the cooperation and transference of experience between research centres in Germany (where the EURAD model system was developed) and Portugal, with wide experience in the proposed work, will be indispensable and decisive to get into the topic of atmospheric modelling and dynamics in this study region.