If the new European Commission president hails from the Greens, he or she would appoint a single commissioner responsible for both air quality and the sectors causing air pollution.

"The Greens would make sure that air quality and the polluting causes are a combined responsibility of one commissioner," Marjolein Meijer, a Greens campaign advisor, told EUobserver.

Student or retired? Then this plan is for you.

Bas Eickhout is one of two Green candidates to become president of the European Commission (Photo: euranet_plus)

Other political parties were more reluctant to echo the Greens' pledge.

The current and previous commissions have had one commissioner responsible for environment (and thus air quality), and another responsible for setting standards for industry and enterprises.

This gap in the institutional set-up helped allow the 'Dieselgate' emissions scandal to go undetected until German carmaker Volkswagen admitted to US authorities in September 2015 it had been cheating with emissions tests for years.

The EU commission's environment department had already noticed that emissions in real life were not going down in line with what should be expected as EU limits were being tightened.

However, the commission's industry department ignored requests by their environment colleagues to investigate.

Giving evidence in front of MEPs conducting an inquiry committee into the Dieselgate scandal in 2016, former environment commissioner Janez Potocnik (2010-2014) said that he had "not [been in] the most comfortable position" as environment commissioner.

Because while he was in charge of tackling air pollution, he was not in charge of car emission standards.

"You are deemed responsible for many important challenges and negative issues, but the majority of the solutions are not in your own hands," Potocnik complained.

Following the inquiry committee, the European parliament adopted a set of recommendations, two years ago.

MEPs called on the EU commission "to change its internal structure in such a way that, under the principle of collective responsibility, the portfolio of one single commissioner (and directorate-general) includes at the same time the responsibility for air quality legislation and for policies addressing the sources of pollutant emissions".

EUobserver has now asked the European political parties whether they would carry out this recommendation, if their lead candidate to succeed Jean-Claude Juncker managed to muster support from a majority in the European Parliament after next month's elections.

The Greens were the only group to wholeheartedly do so.

"This would make sure that emissions and air pollution are tackled from one policy perspective," said Meijer, campaign advisor to MEP Bas Eickhout.

Dutchman Eickhout and German MEP Ska Keller are the Greens' two candidates - known as Spitzenkandidaten in the Brussels' bubble - to succeed Juncker.

However, the group currently has only 52 of 751 MEPs.

Juncker's current right-hand man, Frans Timmermans, was less eager to commit to the idea.

The first vice-president of the EU commission, in charge of sustainability and better regulation, runs as the Spitzenkandidat for the Party of European Socialists (PES).

A PES campaign spokesman said "we are fully concentrated on the election campaign for now and it would be premature to talk in detail about how he [Timmermans] would organise the next commission".

But he added that it was "clear that air pollution is an issue of high importance and he [Timmermans] would look carefully at the EP's recommendations and would make sure that there is not a siloed approach to this issue".

The socialists are currently the second-largest force in the EU parliament, followed by the anti-federalist European Conservatives and Reformists (ECR), which is affiliated with the Alliance of Conservatives and Reformists in Europe party (ACRE).

Conservatives reject it

Jan Zahradil is ACRE's spitzenkandidat.

"Given that my campaign is centred around streamlining the work of the European commission I will not commit to the establishment of a single commissioner and DG responsible for air quality legislation and for policies addressing the sources of pollutant emissions," he said in a written statement sent by his campaign advisor.

"That said, it is important to stress that in accordance with the treaties, the European commission works as a college and acts by a majority of its members. Individual commissioners and DGs do not work in a departmental silo," Zahradil said.

He also added that the commission is due to have new powers in the area of car testing, and stressed that it was an MEP from his ECR group that steered the relevant legislative file through parliament.

A spokesman for the European liberals in the ALDE party said he was unable to give a specific answer, but noted that ALDE member parties "do place emphasis on such environmental matters in addition to a desire to reducing emissions and improving air quality so I would trust, if elected, they would make the necessary steps to ensure that effective steps can be taken to this end with the EU assuming a greater leadership role".

The centre-right European People's Party - the largest group in the EU parliament - told EUobserver after publication of this article that it was currently focusing on its promises to European voters.

"The institutional structure of the European Commission will be an important topic for after the elections," a spokesman said.

The European Left did not reply to EUobserver's request.

391,000 premature deaths

Air pollution is one of Europe's biggest environmental and health challenges.

According to the most recent estimates of the European Environment Agency, the lives of 391,000 citizens of the EU were cut short because of air pollution in 2015 alone.

"Air pollution is a major cause of premature death and disease and is the single largest environmental health risk in Europe," the EEA said.

EU parliament elections are on 23-26 May. The mandate of the Juncker commission runs out on 31 October.

This article was updated on Monday 29 April to include a comment from the European People's Party.