Cars will need to meet EU limits on NOx emissions under real-world driving conditions by September 2022, following a vote by European Parliament.

Previously, data on car emissions such as NOx were obtained through laboratory tests but following the shift to real driving emissions (RDE), tests to measure pollutants were carried out on the road.

However, emissions from vehicles in these conditions tended to be much higher, so to address technical uncertainties regarding measurements obtained through portable emission measurement systems, the Commission introduced the ‘conformity factor’ which allows for higher emissions under real driving conditions to take into account a margin of error.

To reduce NOx emissions, the European Parliament wants the conformity factor currently in place to be annually lowered, based on assessment by the Joint Research Centre, until it ceases to apply by September 30, 2022.

After this date only the raw data from tests carried out under real driving conditions would be used to determine compliance with EU emission limits.

Esther De Lange, the European Parliament’s rapporteur on the file, said: “We have to be realistic about the discrepancy between emissions measured in laboratories and those measured in real-driving conditions by taking into account statistical and technical uncertainties linked to these measurements.

“At the same time, it’s important to show ambition by gradually lowering the value for the conformity factor through annual downward revisions, based on the scientific assessments of the Joint Research Centre.”

Parliament is now ready to start negotiations with EU member states to agree on final rules.

Alex Keynes, clean vehicles manager at European sustainable mobility NGO Transport & Environment, added: “Allowing carmakers to pollute more because their cars are polluting is like telling the police to stand down because the robbers are already in the bank.

“The health of thousands of Europeans is at risk because of air pollution. Carmakers have the means to meet nitrogen oxide limits in the real world, so this scandalous exemption must be stopped without further delay.”

He added “Carmakers should invest their time and energy producing zero-emission vehicles, rather than lobbying for exemptions to continue to pollute in our streets.

“Member states must show the way and abolish the conformity factor as soon as possible.”