The UK government has failed in its legal duty to protect people from the harmful effects of air pollution, the supreme court ruled on Wednesday.

The ruling by five judges – the first time a UK court has recognised that the government has failed in efforts to meet European air pollution limits – delighted air pollution campaigners.

It means the government faces stiff European fines and British cities may have to ban cars and limit the entry of heavy good vehicles to dramatically reduce air pollution.

But because the court also ruled that the European court of justice will have to step in to clarify some legal issues, the government may be able to delay acting for up to a year.

“This landmark decision … paves the way for the European commission to take legal action against the UK,” said James Thornton, ClientEarth chief executive. “The ruling marks a turning point in the fight for clean air and will pile the pressure on the environment secretary, Owen Paterson. He must now come up with an ambitious plan to protect people from carcinogenic diesel fumes. Until now, his only policy has been lobbying in Europe to try and weaken air pollution laws.”

The group’s case concerned 16 cities and regions, including London, Manchester, Birmingham and Glasgow, which government plans show will suffer from illegal levels of NO2, nitrogen dioxide – until as late as 2020 or 2025.

The supreme court confirmed that because the government is in breach of the EU air quality directive, “the way is open to immediate enforcement action at national or European level”. However, before deciding whether to take further action to enforce the law, it has referred a number of legal questions to the court of justice of the European Union.

The way is now open for the European commission to take infringement action against Britain without waiting for any ruling by the European court of justice. This could theoretically lead to heavy fines.

continue reading UK government failing legal duty on air pollution, supreme court rules | Environment | guardian.co.uk.