The Government does not expect legal limits for nitrogen dioxide air pollution to be met in London, Birmingham and Leeds until 2030.

This is largely due to the failure of the European vehicle emission standards for diesel cars to deliver the expected emission reductions of NOx, according to the Department for Environment Food and Rural Affairs (DEFRA).

Friends of the Earth has raised concerns about the impact on health of the failure to meet EU targets earlier.

Jenny Bates, air pollution campaigner at Friends of the Earth, said: "Failure to meet air pollution limits in three of our major cities for another sixteen years would have serious impacts on the health of thousands of people.

"These air quality rules should already have been met. Government, councils and the London Mayor must make this issue an urgent priority, and end this national scandal.

"Rapid steps to ban the dirtiest vehicles and cut traffic levels must be taken, and road-building plans that will simply add to the problem should be abandoned."