The worst areas and causes of air pollution were revealed by the Mayor of London this week. Included on the black list were sections of the M25, M4, Euston Road/ Marylebone Road and the A12 Cambridge Park Road.

The London Atmospheric Emissions Inventory, in which the latest pollution figures were disclosed, is part of the Mayor's Environment Strategy which involves ongoing research into air quality.

The data collected is used to raise awareness among relevant organisations and public bodies such as the London Boroughs.

The air containing the highest emissions of nitrogen oxide were found to be sections of the M25 and M4 motorways, Euston Road/ Marylebone Road and A12 Cambridge Road. The A40 Cumberland Gate, A12 Cambridge Park Road, and Euston Road were also found to be carrying the highest concentrations of fine particulate. Fine particulate (PM10) is microscopic particles formed from most reactions involving combustion.

Traffic made up by lorries, vans and private cars are the leading culprits for NOx and PM10 emissions, accounting for 85%.

As the number of new vehicles complying with higher emission standards come on to the roads, by 2010 it is estimated that nitrogen oxides from road traffic will be reduced by 43 per cent and particulates by 35 per cent.

However the Mayor warned that even by 2010 some area of the city would still have levels of air pollution far higher than the recommended level.

"More needs to be done to improve London's air quality," he said. "which is why Transport for London is trailing hydrogen fuel cell buses and I am introducing higher emissions standards for London's taxi fleet.

"I am committed to introducing a Low Emission Zone for London, making London the only major city in the world to have taken such a radical step to tackle air pollution."