City centre congestion charges do nothing to cut pollution or boost air quality, according to researchers at Kings College, London.
The study has concluded that the congestion zone has made no difference to the levels of smog and noxious gases in the city and that some pollutants actually rose when the charge came in because of the extra buses and taxis on the roads.
Following the study, which analysed air quality two years before and after the Congestion Charge was introduced in London, Professor Frank Kelly, environmental health expert at the College, said congestion charges that covered only small parts of cities did little to cut air pollution.
'The problem was that the central zone was only 1% of the Greater London area,' he said. 'Even though it reduced the traffic by 40,000 vehicles a day, there was a dramatic increase in the number of buses. So the benefit was to some extent offset by the rise in public transport.'
The findings come as councils across the UK are being urged to introduce their own urban road pricing schemes by the Government.
A spokesman for Transport for London said congestion charging had cut emissions of nitrogen oxides by 8% and particulate matter created by diesel engines by 15%.