According to PSR (OECD) and DPSIR (EEA) models, Environmental Agencies are in charge of measuring the State and Pressure and evaluate the Impact in order to define the most suitable Responses; this implies data analysis and reporting activities, as one of their core responsibilities. Environmental Information Systems (EIS) support these activities by combining the advantages of first-rate consolidated technology (such asBusiness Intelligence and Data Warehouses) to specific technical architectures tailored to environmental management tasks. E2SP (Environmental Enterprise Service Provider) is a online reporting and forecasting platform, providing a cost effective, Internet based EIS and Decision Support System in ASP (Application Service Provider) mode. Tasks such as data integration, data analysis through OLAP (On Line Analytical Processing), impact analysis and forecasts through mathematical models, emission inventories, indices/indicators calculation, reporting, are supplied in an integrated environment as on line services to public authorities and private industries. E2SP project, funded by the eTEN program of the European Commission, allowed to deploy two service centres and to develop the business case study, described in this paper, to verify the viability of the ASP approach to EIS in a trans-national context, starting from the air quality theme.