Air quality is a matter of rights. A substantive right to clean air for individuals has emerged from European Union legislation, the corollary of duties made ever tighter by the Court of Justice of the European Union (CJEU). In delivering on these developments, reliance on two factors was and remains of crucial importance: litigation and citizen science. The present article focuses on the CJEU’s interpretation of European Union law on ambient air quality and on how that interpretation impacts domestic jurisdictions. The article explores the apparent absence of rights talk in such legislation, while showing in parallel how air quality, health and rights constantly intersect and form an undeniable backdrop, or context, that favours – and even requires – a stricter protection of individuals against air quality degradation.