This analysis considers and reviews the judgment of the Court of Justice of the European Union in Case C-723/17 Lies Craeynest and Others v Brussels Hoofdstedelijk Gewest and Brussels Instituut voor Milieubeheer [2019] ECLI:EU:C:2019:533, which followed a preliminary reference by the Nederlandstalige rechtbank van eerste aanleg Brussel (Dutch-language Court of First Instance of Brussels) concerning the interpretation of Directive 2008/50/EC on ambient air quality and cleaner air for Europe. The Craeynest judgment strengthens the right to clean air in the European Union, offering new tools for citizens to hold authorities accountable before national courts. [---]