ICARUS will develop innovative tools for urban impact assessment in support of air quality and climate change governance in the EU. This will lead to designing and implementing win-win strategies to improve the air quality and reduce the carbon footprint in European cities. An integrated approach will be used for air pollution monitoring and assessment combining ground-based measurements, atmospheric transport and chemical transformation modelling and air pollution indicators derived from satellite, airborne and personal remote sensing. The ICARUS methodology and toolkit will be applied in nine EU cities of variable size, socio-economic condition and history (Basel-Stadt is a case-study city). Technological and non-technological measures and policy options will be analyzed and proposed to the responsible authorities for air pollution and/or climate change at the city level. Based on the advanced monitoring and assessment tools outlined above, a cloud-based solution will be developed to inform citizens of environment-conscious alternatives that may have a positive impact on air quality and carbon footprint and finally on their health and motivate them to adopt alternative behaviours. Agent-based modelling will be used to capture the interactions of population subgroups, industries and service providers in response to the policies considered in the project. Thus, social and cultural factors, socio-economic status (SES) and societal dynamics will be explicitly taken into account to assess overall policy impact. Our findings will be translated into a web-based guidebook for sustainable air pollution and climate change governance in all EU cities. ICARUS will develop a vision of a future green city: a visionary model that will seek to minimize environmental and health impacts. Transition pathways will be drawn that will demonstrate how current cities could be transformed towards cities with close to zero or negative carbon footprint and maximal wellbeing within the next 50 years.