ICARUS project developed a first-of-a-kind transdisciplinary methodology and toolkit for integrated impact assessment so that air quality improvement, climate change mitigation and health promotion can be evaluated efficiently in key sector policies. To this aim ICARUS developed innovative tools for urban impact assessment leading to design and implement win-win strategies to improve the air quality and reduce the carbon footprint in European cities. In the frame of the project, state-of-the-art technologies for fusing the necessary environmental and ancillary information were employed to allow for cost-effective air pollution monitoring and assessment. The tools developed allow the analytical accounting of the main industrial and area emission sources in the area and the creation of precise and updated emission inventories. An integrated approach was used for air pollution monitoring combining ground-based measurements, atmospheric transport and chemical transformation modelling and air pollution indicators derived from satellite, airborne and personal remote sensing. Thus, air quality was readily assessed across different spatial scales in the participating cities. Agent-based modelling was 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 were explicitly taken into account to assess overall policy impact.