Background The introduction of the EU’s Thematic Strategy for air quality (COM 2005 446) and Directive 2008/50/EC on ambient air quality and cleaner air for Europe emphasises the importance of the issue of air quality. Despite the legislation, some regions in Europe produce or maintain pollutant levels that threaten human health and ecosystems. This is the case in the Po Valley, Italy, where the combination of high population densities, high emission levels and poor meteorological dispersion has had an adverse impact: local populations are affected by high levels of fine particulate matter (PM2.5) and ecosystems are threatened by high levels of ozone and eutrophication. Problems associated with air pollution are also affecting Central Europe. For example, in Alsace, France, air quality has deteriorated as a result of high population density in the Upper Rhine valley, high levels of border traffic across France, Germany and Switzerland, and the presence of important industrial areas (the Ruhr region in northeast Germany and around Basel). Levels of particulate matter and ozone compounds are often above the maximum amount. Objectives The main goal of the OPERA project was to develop a methodology to assess the efficiency of planned measures for tackling air quality. It also aimed to draw up guidelines to support local authority planning for regional policies in order to comply with actions taken at national and European level to reach the required air quality standards. The project would devise methods that allow local authorities to identify and apply the most effective – and economical viable – abatement measures (in line with the national and international frameworks).These would also take into account possible synergies with greenhouse gases (GHG) emissions reduction measures. Specifically, the project aimed to: Develop a methodology to help local authorities (i) prepare, implement and monitor air quality plans to reduce population exposure to PM10, NOx and O3 pollution and ecosystems exposure to NOx and O3, (ii) integrate regional air quality plans within national and European plans, and (iii) assess the synergy between actions to reduce poor air quality and actions to limit climate change impacts; Create an integrated assessment software tool (RIAT+) to support the proposed methodology, thus maximising environmental benefits at fixed costs, and minimising costs at fixed environmental benefits; Apply this integrated tool in the Emilia-Romagna and Alsace regions, while setting up a register of existing and new emission reduction measures (technical and non-technical) in the two regions; Devise a standard set of quantitative indicators to monitor the effectiveness of action plans, and define guidelines for regional authorities to apply the methodology and tool; Draw up guidelines and create a tool for local administrations, technical organisations and environmental agencies to integrate local planning for compliance with national and European air quality policies; and Disseminate product and results at European level. Results The OPERA project developed a methodology and a tool, RIAT+, that functions as a Decisional Support System (DSS) for local/regional authorities in designing and assessing efficient air quality action plans. The RIAT+ tool helps regional decision makers operating on limited budgets to carry out efficient measures for tackling several pollutants in different ways in order achieve EU air quality standards. RIAT+ is a regional, integrated, assessment, stand-alone software that complies with EU standards on data exchange (Directive 2007/2/EC establishing an Infrastructure for Spatial Information in the European Community - INSPIRE DIRECTIVE). It is an open source software that is released to end-users under a public license. The RIAT+ system acts both as regional assessment software and as an integrated modelling environment through which air quality simulations on a regional scale can be produced. As a modelling system, RIAT+ uses air quality indicators to assess potential pollution abatement measures in light of EU limits and future concentration reduction deadlines. It incorporates Artificial Neural Networks (ANNs), to capture non-linear relationships between pollutant emissions and concentrations. The tool's ability to determine the cost of measures in advance, particularly structural measures, makes it especially useful to public administrations. RIAT+ supports decision-makers in the definition of air quality plans by suggesting optimal emissions reduction measures to improve air quality, given a pre-defined budget. Users may introduce their own source of information/data (e.g. emissions inventories, air quality models, abatement technologies) on top of default assigned values. This allows a more precise assessment of the impact of user-defined abatement measures on regional/local air quality. This tool was tested in the Emilia Romagna and Alsace Regions, drawing up and assessing related air quality action plans. In Emilia Romagna the application of the RIAT+ tool led to the setting of emissions reduction targets in the Air Quality Plan PAIR 2020. A preliminary document was approved by the regional government in July 2013. It defines the emissions reduction targets at regional level for the main pollutants responsible for PM and ozone pollution (NOx, PM10, VOCs, NH3 and SOx) and the main intervention sectors. The plan will be implemented through an integrated approach involving all the relevant sectors, such as the transport, energy, agriculture and industrial sectors. Special attention will be paid to the sustainable management of urban areas, reducing greenhouse gas emissions and improving air quality. In Alsace, the application of the RIAT+ has led to the definition of a list of potential measures to be possibly included in the next revision of the Regional Scheme on Air, Energy and Climate Alsace (SRCAE). It is also enabling policy makers to highlight potential new actions. The project also set up a register for recording existing and new emission reduction measures, technical and non-technical, in the two project areas. Each measure is defined by its abatement efficiency and cost, and linked to site-specific implementation strategies. Full documentation helps support new users. Furthermore, the project established and applied a standardised set of quantitative indicators for monitoring the effectiveness of air quality action plans. It also drew up guidelines for local administrations and environmental agencies (national priority for Italy) to integrate local planning into national and European air quality policies, thus helping to develop capacity building. The results of the project were disseminated to a targeted audience of technical and political actors/stakeholders involved in air quality management and policies on a regional/local level. An after-LIFE communication strategy foresees further promotion of RIAT+ among new users and the steering of future developments through courses, workshops and publications. Moreover, the Joint Research Centre is contributing to the continuation of the project by initiating networking for regional/local applications of the RIAT+ tool. Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).