In the framework of the LIFE -Environment Program, The National Institute of Meteorology and Hydrology (NIMH) carries out a demonstrative project concerning with the urban impact of air pollution. The project Life ASSURE has focused on impacts of long term estimation procedures of pollution levels in the atmosphere, and in the surface and underground hydrologic environment in the context of urban panning. Thus, the ASSURE system is able to provide data for evaluating the pollution potential of each objective of urban planning, and to encourage or discourage those urban or industrial scenarios which could constitute a pollution risk for environment, and consequently to the population health. In the first part of this paper the way in which dispersion model results are integrated in the operational final system on the Open-GIS platform is described. In the second part of the paper the statistical performances of two dispersion models are presented.