The Supreme Court rules Britain must plan immediately to reduce nitrogen dioxide levels to meet EU targets..

The Government has been ordered to act immediately to comply with European air pollution limits.

The decision by the Supreme Court relates to nitrogen dioxide, largely produced by diesel engines, and it could lead to tight controls on diesel vehicles in Britain’s largest cities.

The case was brought against the Environment Secretary by campaign group ClientEarth who argued that cities including London, Birmingham and Leeds would not meet EU pollution limits until 2030 – 20 years after the 2010 deadline.

The panel of five judges unanimously ruled the Government must submit a new air quality plan to the European Commission by the end of the year.

ClientEarth had argued that only enforcement action would remedy “the ongoing breach by the UK of EU law on nitrogen dioxide limits”. The group claimed air pollution in the UK causes 29,000 early deaths a year; more than obesity and alcohol combined.

Representing ClientEarth, Ben Jaffey told the court: “The UK had more than 10 years notice of the implementation of these limits. The UK has now been continuously in breach of those limits since January 2010.

“A maximum of five years time extension was available, expiring by 1 January, 2015 at the latest. This period has also now expired, but the UK never applied for an extension in many areas. The UK therefore remains in breach.”

Speaking after the verdict, ClientEarth’s environment lawyer Alan Andrews told Sky News: “We are delighted with the verdict that the Supreme Court has made which will save thousands of lives in the UK.

Mr Andrews said he was “baffled” the issue had not been mentioned by political parties during the election campaign and that a comprehensive plan was required to tackle diesel pollution.

“We think a national network of low emission zones which keep the most polluted diesel vehicles out of our towns and cities is the best and most effective option,” he said.