Banning diesel buses from city centres would have a 'devastating impact on local communities', a leading transport expert has warned.
David Begg, visiting professor at Plymouth University and former chairman of the Government's Commission for Integrated Transport, said a blanket ban would lead to the loss of eight in 10 services, increased social deprivation and higher unemployment.
Local authorities with roads breaching legal pollution levels have been given until March next year to publish draft plans to tackle the problem in their areas.
Diesel vehicles are widely expected to be targeted in new clean air zones with new restrictions or fines.
But Prof Begg said such bans would 'demonise and penalise' the latest generation of clean British diesel buses which can deliver 95% reduction in harmful emissions.
He called on local authorities to halt blanket bans and instead target older diesel cars which are the biggest contributors to air pollution.
Prof Begg said: 'While local government rightly try to take dirty diesel vehicles off the streets, there is a danger they will demonise and penalise a new generation of independently-tested clean diesel buses that are in fact part of the solution, not the problem, to excessive air pollution.'