A landmark ruling on air pollution in London by the Supreme Court could have implications for proposals for a third runway at Heathrow.

Five judges unanimously ordered Secretary of State for Environment Elizabeth Truss to consult on strict new air pollution plans, which must be submitted to the European Commission by the end of the year.

The plans require a Government crackdown on the UK’s high nitrogen dioxide (NO2) pollution levels.

Supreme Court judge Lord Carnwath said the court was “in no doubt about the seriousness” of the UK’s breach of EU law by failing to meet legal pollution limits and the country could risk fines from the European Commission which total £300m.

The EU Air Quality Directive demanded the UK brought pollution down to legal limits by 2010 or apply for an extension by 2015.

In 2011, the Government said a number of areas, including London, would be unable to comply by 2015 and said the law allowed it to comply “as soon as possible”.

Hacan campaigner John Stewart, who opposes a third runway being built at Heathrow, believes the ruling could put a stop to expansion plans.

He said: “This is a potential show-stopper as far as a third runway is concerned. “It is difficult to see how any Government will get away with backing a new runway at Heathrow when the plans it is now required to draw up urgently to present to the EU say it must come up with a coherent plan to cut air pollution.”

London Assembly member Stephen Knight, chairman of the London Assembly environment committee, said the decision should act as a “wake-up call to politicians of all parties”.

He said: “Londoners have suffered too long from the dangerous health effects of air pollution and will welcome this judgement.

“Without more decisive action, a child born today might be able to vote before they gain the right to breathe clean air.”