A campaign led by medical professionals is calling for all diesel cars to be banned from London.
Doctors Against Diesel claim 9,400 Londoners a year die prematurely from breathing in toxic fumes from diesel engines.
Paris, Madrid, Mexico City and Athens have committed to a ban on diesel vehicles by 2025.
Opponents to the campaign have called the proposals "impractical" and warned a blanket ban could "backfire".
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