Bulgaria, Hungary, Poland, Romania, Slovakia, Spain, and the Netherlands "have not taken sufficient action to improve air quality", said the report, a joint effort by the European Court of Auditors, 14 national audit offices from Europe, and the Israeli national audit office. The report also covered non-EU countries Albania, Georgia, Israel, Kosovo, Macedonia, Moldova, and Switzerland.

"The national governments in question have not given sufficient priority to the problem of air pollution, with all the attendant consequences for human health," the report stated. Estonia was the only audited EU country which did not break EU air pollution limits."While the situation is improving and air quality has benefited from cuts in emissions, the EU member states included in this audit (except for Estonia) still do not comply with the EU's air quality standards," it went on. The European Court of Auditors has previously called air pollution "the biggest environmental risk to health in the European Union". The European Environment Agency (EEA) said last year that around 391,000 people in the EU died prematurely in 2015 because of air pollution. EEA director Hans Bruyninckx called air pollution an "invisible killer".

Despite some progress, EU countries have been failing for years now to clean up their air. The European Commission is in charge of making sure that national governments do what they had promised at EU-level in the directive on ambient air quality, adopted in May 2008.The only legal tool the commission has is the so-called infringement procedure, which is a series of escalating steps involving sending stern letters, and culminating in a referral to the EU's highest court in Luxembourg. Last May, the Brussels-based EU executive referred six EU states to the European Court of Justice.However, of the seven audited EU countries for which the report concluded their respective governments took insufficient action, only Hungary and Romania were among the six taken to court by the commission.

The other four were Germany, France, United Kingdom, and Italy.But Slovakia and Spain, which are scolded in the audit offices' report, with the Czech Republic, escaped court referral in May 2018. EU environment commissioner Karmenu Vella said that was because these three countries had announced measures that would improve air quality "in a reasonable time frame".But according to the Slovakian supreme audit institution "a comprehensive strategy for air protection is missing [in Slovakia] and there is no national emission reduction programme". The report noted that the Slovak ministry of environment was "preparing a new strategy for air protection which is expected to be adopted in 2019".On Spain, the report noted that while Madrid had established a National Air Quality and Atmosphere Protection Plan, "only some of the relevant measures have been implemented".

The Spanish audit office said that 62 percent of the measures had either been implemented only partly or not yet. The report also said there were several examples of improvements across Europe. However, it was not enough.LettersThe audit results raise questions over the effectiveness of the commission's infringement procedure in forcing member states to stick to EU rules on air pollution.In November, the commission sent so-called letters of formal notice to the Czech Republic and Bulgaria, telling them "to bring national legislation into line with the Air Quality Directive".

It sent a similar letter to Belgium on poor air quality. Also in November, the commission reminded Bulgaria that the Court of Justice of the EU had already ruled in 2017 it was breaking EU law by not cleaning up the air, and threatened with sending Bulgaria back to the court – which could ultimately lead to fines.This was eight months after EU commissioner Vella told press Bulgaria's air quality had been improving since the court ruling. Earlier in January, the commission sent France, Greece, and Sweden letters of formal notice to fight air pollution.