Cities and regions present complex challenges in the areas of transport and environment. Consequently, local and regional authorities are keen to find efficient and integrated solutions for their environmental and traffic problems. The pressure on European cities and regions to implement the related EU regulations on air quality has led to a multitude of initiatives and isolated solutions, often with no common approach. Initiatives are required to develop better and more efficient solutions that go beyond the obligations of the related EU directives and that create synergies through the sharing of knowledge and experience. CITEAIR aims to develop improved and more efficient solutions to assess the impact of traffic on air quality in large urban areas. Through close cooperation, exchange of experience and joint developments with European Cities and Regions, the program will inform professional users and the public on the environmental situation and offer guidance on efficient measures to abate adverse environmental situations. Other municipalities are encouraged to contribute to the work via a user network. Achievements: Achievements so far CITEAIR developed better and more efficient solutions to assess the impact of traffic in large urban areas and informing professionals and the public on the environmental situation. The project has developed efficient approaches and practical solutions to inform the public on the environmental situation, has identified the main components of a Decision Support System (DSS) suitable to be transferred to other cities and regions in Europe, and collected information on efficient strategies for urban air quality management. CITEAIR provides near real-time comparative environmental data that is both easily understood by the wider public and a useful tool for air quality technicians and policy makers. CITEAIR was invited to give a presentation at the Committee for Environment, Public Health and Food Safety of the European Parliament. The main achievements are described in the following. Public information: The project has developed the first European Common Air Quality Index (CAQI) for the pollutants NO2, PM10, O3, CO and SO2. The CAQI was included in a review of different air quality indices performed by the European Topic Centre for Air Quality and Climate Change. In addition, CITEAIR developed a Year Average Air Quality Index (YACAQI). The calculation of this index differs from the hourly and daily indices by adopting the 'difference to target' principle. The CAQI and the YACAQI have been presented at various conferences and workshops and are implemented on the Common Operational Website (COW) www.airqualitynow.eu. The COW collects air quality data from monitoring stations representing urban background and roadside conditions, calculates and presents the indices to allow an easy interpretation and comparison of the environmental situation in a multitude of cities and regions. The COW is designed in a flexible manner to accommodate air quality data from a multitude of cities and regions. At the end of the project 25 Cities deliver their air quality data to the COW. The CITEAIR project is open to local and regional authorities who wish to subscribe and compare real time air quality data within the framework of this project. Decision support system (DSS): The cities involved in this project are operating and further developing their DSS's. Taking advantage of the existing experiences, steps have been undertaken to analyse the situation in the Emilia Romagna Region and to identify the most appropriate components (e.g. models, interfaces) of a DSS to assess the environmental impact of traffic. Based on this analysis the transfer of part of such a DSS to Emilia Romagna has been performed Environmental management strategies: The scope of management strategies has been widened to include examples from outside the cities involved in the project. The work on environmental reporting is progressing. CITEAIR has prepared drafts of separate guidebooks, one on Urban Air Quality Management and one on City Annual Air Quality Reporting.