The Mayor of London is scrapping the third phase of the Low Emission Zone (LEZ) which had been due to include light goods vehicles and vans up to 3.5 tonnes.
Boris Johnson claims the proposals - set to come into force from October 2010 - would have had a detrimental impact on about 90,000 owners of smaller vans and minibuses using the zone each year as they would have faced bills of up to £2,000 for pollution abatement equipment, or £15,000 for a new vehicle.
Alternatively, they would have faced a £100 daily charge or fine of £500 for entering the zone.
Johnson says he is "100% committed" to the two existing phases of the scheme, which, he believes have "proved effective".
He adds: "Although the LEZ has been successful in tackling the worst polluters, and will continue to play an important role, it is not the right time to press ahead with extending it to include smaller vehicles like vans and minibuses."
Under the LEZ, vehicles are required to meet the Euro-3 emissions standard or above.
The first phase of the LEZ came into effect in February 2008 and covered diesel trucks of more than 12 tonnes, while diesel lorries of more than 3.5 tonnes were covered by the second phase of the scheme, from July 2008.
However, Gordon Telling, the Freight Transport Association's head of policy for London, claims the LEZ's benefits have been "completely overestimated".
"Taxpayers' money has been wasted on publicity, signage and cameras to catch just a handful of older, more polluting trucks," he says.
"The cost of finding this out has been about £50m in set-up costs and a further £10m in annual running costs. At least now the damage has been limited and we can start to look at more intelligent ways of reducing emissions in the capital without more companies being put out of business."