The paper describes the use of Geographical Information Systems in the framework of the realization of regional air quality management plans. The criteria for represented area, point and line emissions sources are briefly resumed. Particular emphasis is place on methodology for spatial distribution of area emissions on 1 km x 1 km grid, particularly on the use of the official EC cartography related to land use. For area emissions, the municipal level seems to be the most reliable defined to estimate emissions. Inside the municipality a square grid mesh is built-up to evaluate emissions for the application of diffusion models. To disaggregate pollutant emissions from the municipal level to the mesh level, the methodology of proxy variables is used. When the emissions which has to be distributed depends on an extensive variable (a variable proportional to level of covering of a single mesh as for example forests) the level of covering is utilized as proxy variable. In this case, through the maps of land use, developed within the EC CORINE Land Cover, it is possible, for every typology of classification, to calculate the covering on every single mesh. Finally, in the paper the representation of pollutant concentration data coming from air quality monitoring network and grid representation of air quality dispersion models data is resumed. The methodology has been applied to prepare emission inventories in areas with large urban and/or industrial agglomerates (Venice, Florence, Piombino, Rossano Calabro, and Roma) and now is in progress within regional air quality management plans (Trento, Toscana, Bolzano and Liguria). Transactions on Information and Communications Technologies vol 18, © 1998 WIT Press, www.witpress.com, ISSN 1743-3517