Case C-635/18: Judgment of the Court (Seventh Chamber) of 3 June 2021 — European Commission v Federal Republic of Germany (Failure of a Member State to fulfil obligations — Environment — Directive 2008/50/EC — Ambient air quality — Article 13(1) and Annex XI — Systematic and constant exceedance of the limit values for nitrogen dioxide (NO2) in certain zones and agglomerations of Germany — Article 23(1) — Annex XV — Exceedance period to be ‘as short as possible’ — Appropriate measures)