A consultation is now under way on proposals to expand London's Ultra Low Emission Zone (ULEZ) across the entire capital by next summer.

Mayor of London, Sadiq Khan, is proposing to extend the scheme’s boundary from the North and South Circular Roads to the whole of Greater London from August 29 next year.

The ULEZ was initially launched in central London in April 2019, it then expanded to form its current incarnation on October 25 last year.

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

The consultation is being conducted by Transport for London.

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.

It warned that the capital is suffering a “toxic air crisis”, with around 4,000 premature deaths in 2019 attributed to filthy air.

The boroughs of Barnet, Bromley, Croydon and Havering had the most deaths, demonstrating that poor air quality “is not just a central London problem”, according to Mr Khan’s office.

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

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 exempt.

Boroughs not already or partially covered by the scheme include Brent, Redbridge, Newham, Barking and Dagenham and Havering.

Havering politicians across the political divide have largely condemned the proposals.

Local authorities such as Islington, Hackney, Camden, Haringey and Tower Hamlets have been included in the zone since last year.

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

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