Case C-488/15: Judgment of the Court (Third Chamber) of 5 April 2017 — European Commission v Republic of Bulgaria (Failure of a Member State to fulfil obligations — Environment — Directive 2008/50/EC — Ambient air quality — Article 13(1) — Annex XI — Daily and annual limit values for PM10 concentrations — Systematic and continuous exceedance of the limit values — Article 22 — Postponement of the deadlines set to attain certain limit values — Conditions under which applicable — Article 23(1) — Air quality plans — ‘Shortest possible’ exceedance period — Appropriate measures — Information needed for an assessment)