Sadiq Khan: government must pay drivers £3,500 to scrap diesel cars

London mayor says 500m plan could help tackle growing crisis over poor air quality in the capital

London's air is so polluted that motorists should be given up to 3,500 to persuade them to scrap their old diesel cars and vans and replace them with cleaner vehicles, according to the capital's mayor, Sadiq Khan.

The nitrogen dioxide emitted by diesel cars is a key contributor to London's poor air quality, which is so bad that City Hall now advises the public to avoid going out unnecessarily on the worst-affected days.