While air quality monitoring is a European obligation to improve human health and environmental quality under Directive 2008/50/EC, Member States are free to choose the tools for implementing actions on their territories designed to inform the public. In the cross-border area concerned, each of the regions (Flanders, Hauts de France and Wallonia) suffers the same type of air pollution but adopts its own methodologies and tools for air quality management. Faced with this inconsistency, the transfAIR project aims to bring together the knowledge and know-how of air quality operators in the three regions so that they can work in a complementary way and disseminate harmonised, clear and consistent information and communication to the population. The project also aims to promote citizen mobilisation and generate awareness among the population, enabling them to assume the status of responsible citizens, become stakeholders of sustainable development in the cross-border territory concerned.