London’s Ultra Low Emission Zone (Ulez) will be expanded to cover the entire city under plans announced by mayor Sadiq Khan to cut pollution and congestion.

Mr Khan has asked Transport for London (TfL) to consult on extending the scheme’s boundary from the North and South Circular Roads to the whole of Greater London by the end of next year.

Drivers of vehicles which do not comply with minimum emissions standards are charged a daily fee of £12.50 for entering the Ulez area.

Analysis by the PA news agency found that more than 3.5 million more people will live within the Ulez if it is expanded as planned.

The mayor’s office estimated that an additional 135,000 vehicles would be affected per day.

Whether or not a vehicle is liable for the charge depends on how much nitrogen dioxide (NO2) it emits.

(PA Graphics)(PA Graphics)

NO2 damages lungs and can exacerbate existing conditions such as asthma and lung and heart disease.

For diesel cars to avoid the charge they must generally have been registered after September 2015, while most petrol models registered from 2005 are also exempt.

Mr Khan has ruled out introducing a Clean Air Charge, which would have affected drivers of all but the cleanest vehicles.

He will also not go ahead with a proposal to charge drivers of vehicles registered outside London for entering the capital.

Mr Khan, who announced his plan to expand the Ulez on a visit to Forest Hill School in south-east London, said: “In weighing up the different options, the rising cost of living was a key consideration for me.

“Because at a time when people’s budgets are under pressure, I’m not willing to ask people to pay more unless I’m absolutely convinced it’s justified to save lives and protect the health of Londoners.

Air pollution in LondonSmog over London (Nicholas T Ansell/PA)

“I believe the proposal to extend the Ulez London-wide will have the biggest effect on emissions and congestion relative to the potential financial impact on Londoners as a whole.

“We are also proposing to introduce the biggest scrappage scheme feasible to help Londoners on low incomes, disabled Londoners and businesses.”

The Ulez was only expanded from the Congestion Charge area to the North and South Circular roads in October 2021.

But Mr Khan said there is “still far too much toxic air pollution permanently damaging the lungs of young Londoners and leading to thousands of deaths every year”.

The mayor has also asked TfL to explore how motorists can be charged on a per mile basis depending on how polluting their vehicles are, the level of congestion in the area and access to public transport.

Sadiq Khan Mayor of London Sadiq Khan (Victoria Jones/PA)

But a City Hall document notes the required technology for such a scheme is “still years away from being ready”.

RAC head of roads policy Nicholas Lyes said expanding the Ulez is “preferable to the other charges that the mayor previously mooted”.

But he warned it is “vital” that Londoners have “enough time to upgrade to compliant vehicles”.

Michael Lloyd, of the Federation of Small Businesses, said there is “great cause for concern”.

He insisted that companies “want to do the right thing by the environment” but many “simply cannot afford” to replace their vehicles with Ulez-compliant models.

He called for the proposed scrappage scheme to be “all-encompassing” to support small businesses.

Nick Bowes, chief executive of think tank Centre for London, said: “Today’s announcement is another step forward for cleaner air in the city.

“To make it fair for all Londoners, it needs to be accompanied by measures to improve public transport in outer London and help the least well-off who’ll be hit the hardest.”