MANY people may not realise because of its invisibility, but London's dirty and polluted air is a massive threat to our health. The air in our city is among the most polluted in Europe.

Tiny airborne particles are emitted by lorries and boilers, particularly from diesel fuel. These cause respiratory problems, asthma, lung cancer and heart disease and contribute to the 8,000 premature deaths a year in greater London due to bad air.

London is in breach of strict European clean air standards - ones the then government signed up to - that came into force in 2005. Legal action was looming to enforce a clean-up, but last week the EU granted the UK more time to improve London's air quality. This was strictly on condition that the mayor and the government take urgent action to tackle this dangerous pollution.

Of course, it shouldn't even have come to this. It's a disgrace that the EU has to intervene to protect Londoners' health because of years of inaction. But I'm glad the EU takes the coalition government's pledge to fully comply with European air quality standards as one made in good faith, whereas the Labour government's pleas for postponement were rejected because of the lack of reliable promises.

There must now be serious work to get the most polluting diesel vehicles off London's streets, replace the dirtiest boilers and finally make London a safe place to live and breathe. I will play my part in keeping up the pressure.

BARONESS SARAH LUDFORD Liberal Democrat MEP for London

Liberal Democrat European justice and human rights spokeswoman

St Peter's Street London