Background The city of Istanbul, with more than 12 million inhabitants, suffers from serious urban air pollution. The situation has improved as a result of a number of pollution prevention activities, including fuel switching (from coal to natural gas heating), improvement of burning devices, and abatement of industrial emissions. However, air pollution is still one of the main environmental challenges facing the city. The municipality only operates a small network of air quality monitoring stations. Istanbul has neither a proper air quality information system nor a good understanding of the emissions-air quality linkages. Objectives The project aimed to strengthen the capacity of Istanbul municipal staff in monitoring and managing air quality and eventually to improve the quality of urban air in Istanbul. Specifically, the project would develop an advanced GIS-based decision-support system, including a detailed assessment and mapping of the ambient air quality in Istanbul, a comprehensive emission inventory and mapping of air pollution sources, and an air quality model. The Municipality would use the GIS-based decision support system to develop and implement relevant environmental and urban policies for the City of Istanbul. Results In the framework of the project, the beneficiary developed a detailed database, covering industrial pollution sources as well as traffic and heating related pollution parameters. With the support of project partner Dokuz Eylül University, the beneficiary elaborated detailed air quality and meteorological models, which are the basis for the calculation of pollution dispersion scenarios. Training sessions in three different countries (France, Sweden and Russia), allowed the beneficiary to assess different models and approaches used in other countries and to select the approach most appropriate for Istanbul's needs. During the last months of the project, the beneficiary elaborated an air quality management strategy, defining the priorities for future research and investments, and linking the air quality monitoring and modelling system to the municipality's decision-making structure. The beneficiary proved to be very committed during the project, and devoted significant resources from its own budget to the database collection. The beneficiary also confirmed that it intends to cover more parameters than only the five key pollutants currently included into the system. It may, for example, also be possible to monitor greenhouse gas emissions and thus contribute to a better reliability of the Turkish national communications to UNFCCC and to make targeted efforts to decrease climate change related emissions accordingly. Further information on the project can be found in the project's layman report (see "Read more" section).