1.The Commission shall, by 1 April 2020 and every four years thereafter, report to the European Parliament and the Council on the progress made in the implementation of this Directive, including an assessment of its contribution to the achievement of the objectives referred to in Article 1, including:
(a)progress towards:
the indicative emission levels and emission reduction commitments referred to in Article 4 and, where applicable, the reasons for any non-achievement;
ambient air quality levels in line with the air quality guidelines published by the World Health Organisation;
the Union's biodiversity and ecosystem objectives in line with the 7th Environment Action Programme;
(b)identification of further measures required at Union and Member State level to achieve the objectives referred to in point (a);
(c)the uptake of Union funds to support the measures taken with a view to comply with the objectives of this Directive;
(d)the results of the Commission examination of the national air pollution control programmes and their updates pursuant to the third subparagraph of Article 10(1);
(e)an evaluation of the health, environmental and socioeconomic impacts of this Directive.
2.Where the report indicates that the non-achievement of the indicative emission levels and emission reduction commitments referred to in Article 4 could be the result of ineffective Union source-based air pollution control legislation, including its implementation at Member State level, the Commission shall, where appropriate, investigate the need for further action also considering the sectoral impacts of implementation. Where appropriate, the Commission shall present legislative proposals, including new source-based air control pollution legislation, in order to ensure compliance with the commitments of this Directive.