Although outdoor air quality in France is improving for most regulated pollutants, the perception of the French continues to deteriorate. In addition to regulated pollutants, impacting health and ecosystems, new pollutants are emerging. Little observed and measured in ambient air, they raise questions and concerns about their effects. Despite this concern, acting for better air is not always easy and understood. The AQAH project: "Better knowledge to better act on air quality" in Hauts-de-France is anchored on the concerns and challenges of the representative partner territories of Hauts-de-France. Registered in a tryptic "better know, better understand to better act", it involves the actors of the territory (families, young people, associations, elected officials, economic actors, ...). The AQAH project has multiple ambitions: - Understand how air quality has evolved since 1990. Know which emerging pollutants (PUF, PFAS, Pesticides and Microplastics) we are exposed to. - Sharing knowledge as close as possible to the inhabitants. - Involve the actors of the territory to identify and experiment with innovative, challenging solutions to facilitate awareness and encourage the transition to action individually and collectively - Initiate innovative, acceptable and duplicable actions by the actors of the territories in favor of a better air