A new survey for The Independent has found the majority of the public is now in favour of banning the most-polluting vehicles from city centres.
Some 51 per cent of respondents agreed with this suggestion, with only 15 per cent against and the remainder not expressing a view, pollsters ORB said.
Commenting on the reports which shows the public back the Liberal Democrat policy of banning the most-polluting cars from city centres, Liberal Democrat Shadow Transport Secretary Jenny Randerson said: "The air we allow our children to breathe is toxic and is leading to a national health crisis.
"If our water was as contaminated as the air we breathe the Tories would have been forced to take this seriously. Instead they are plying more dirt into the air and pushing through Heathrow expansion with no serious attempts to address the illegal emissions that are endangering people.
"Only the Liberal Democrats are committed to phasing out diesel vehicles and compensating drivers. We want to give all our children a brighter future in a fairer Britain, cleaning up our air will be a move in the right direction."