The COMPAIR innovation project is designed to bolster citizens' capacity to monitor, understand, and change their environmental impact, both at a behavioural and policy level. It unlocks the power of the wider public, including people from lower-socio economic groups, to provide broad granular data around a central theme of air quality, complementing and improving the quality of official datasets and making new information useful for helping to meet environmental aims. The project will achieve its aim by empowering people using a Citizen Science Lab - with a special focus on women, young people, and hard-to-reach groups ? to provide the skills to co-design and undertake environmental scientific experiments around needs and challenges in their locality. By providing innovative, self-assembly, low-cost sensors, dynamic dashboards, and augmented reality tools for collecting, visualising and extracting actionable intelligence from data, anyone regardless of their background, can understand their impact on the environment and explore immediate actions to improve it. Beyond helping to mitigate bad environmental habits at an individual and community level, CS (Citizen Science) data will also be used to mutually enrich other public and private data sources in official city decision making platforms. Thereby helping to increase civic engagement and influence more effective long-term environmental policy. Piloted in the Region of Flanders and the major cities of Athens, Berlin and Sofia, communities, businesses, researchers and public administrations will, for the first time, adopt and benefit from a technology-enabled, collective approach to evidence gathering that fills gaps in existing data sources, and provides new routes to innovation. COMPAIR will raise awareness of, and provide a CS Lab Toolkit, to ensure CS is a trusted approach to tackling complex, systemic and environmental problems that require different perspectives.