Motorists driving older and dirtier vehicles will be charged an extra £12.50 to enter central London from today as a new ultra-low emission zone (ULEZ) came into force.

Petrol cars older than 13 years and diesels older than four years will be hit by the levy.

Sadiq Khan, the Labour mayor of London, said the charge was being introduced to help prevent thousands of deaths from air pollution, adding that the city’s “toxic air is damaging people’s health”.

For the first two and a half years the ULEZ will cover the same area as London’s existing congestion charge, but in October 2021 will be expanded to the entirety of the inner city, out to the north and south circular roads.

But unlike the congestion charge, which costs drivers £11.50 between 7am and 6pm on weekdays, the ULEZ levy is in force 24 hours a day.

The most polluted towns and cities in the UK Show all 25 1 /25 The most polluted towns and cities in the UK The most polluted towns and cities in the UK 25. Middlesbrough 11 micrograms per cubic metre. A report from the World Health Organisation has given figures for fine-particle air pollution across the world. Here follow the 25 most polluted towns and cities in the UK The most polluted towns and cities in the UK 24. Derry 11 micrograms per cubic metre Getty The most polluted towns and cities in the UK 23. Hull 11 micrograms per cubic metre (estimate) Getty The most polluted towns and cities in the UK 22. Coventry 11 micrograms per cubic metre Getty The most polluted towns and cities in the UK 21. London 11 micrograms per cubic metre PA The most polluted towns and cities in the UK 20. Stoke-On-Trent 12 micrograms per cubic metre Getty The most polluted towns and cities in the UK 19. Sheffield 12 micrograms per cubic metre (estimate) Getty The most polluted towns and cities in the UK 18. Sandy, Bedfordshire 12 micrograms per cubic metre Google The most polluted towns and cities in the UK 17. Royal Leamington Spa 12 micrograms per cubic metre Getty The most polluted towns and cities in the UK 16. Prestonpans 12 micrograms per cubic metre Richard Webb The most polluted towns and cities in the UK 15. York 12 micrograms per cubic metre Getty The most polluted towns and cities in the UK 14. Plymouth 12 micrograms per cubic metre Getty The most polluted towns and cities in the UK 13. Nottingham 12 micrograms per cubic metre Getty The most polluted towns and cities in the UK 12. Eccles 12 micrograms per cubic metre (estimate) Rept0n1x The most polluted towns and cities in the UK 11. Grays 12 micrograms per cubic metre (estimate) Getty The most polluted towns and cities in the UK 10. Liverpool 12 micrograms per cubic metre Getty The most polluted towns and cities in the UK 9. Leicester 12 micrograms per cubic metre Getty The most polluted towns and cities in the UK 8. Leeds 12 micrograms per cubic metre Getty The most polluted towns and cities in the UK 7. Chepstow 12 micrograms per cubic metre Getty The most polluted towns and cities in the UK 6. Carlisle 12 micrograms per cubic metre The most polluted towns and cities in the UK 5. Gilllingham 13 micrograms per cubic metre Philip Halling The most polluted towns and cities in the UK 4. Swansea A view of Swansea centre taken from Kilvey Hill January 2016 Getty The most polluted towns and cities in the UK 3. Manchester Manchester, UK - November 24, 2016: View of Manchester city center. Tall buildings an be seen on either side of the road and a tram can be seen passing. People can be seen walking on the pavements. Getty The most polluted towns and cities in the UK 2. Gibraltar Wide view of the rocks of gibraltar from the observation deck Getty The most polluted towns and cities in the UK 1. Scunthorpe Scunthorpe, UK - October 19, 2015. TATA steels' Scunthorpe plant in England which has recently been saved from closure after being bought by the investment firm Greybull Capitla for Â£1. Getty

All vehicle types apart from black taxis are liable for the Ulez charge unless they meet certain emissions standards or exemptions. Non-compliant lorries, buses and coaches face a £100 daily fee.

It is estimated that 100,000 cars, 35,000 vans and 3,000 lorries may be affected every day once the zone is expanded.

The ULEZ was announced by former mayor Boris Johnson, but his successor Mr Khan brought forward the start date and decided to extend it for 2021.

There has been concern that poorer motorists, small businesses and charities will be unfairly stung by the charge as they are less able to afford to upgrade their vehicles.

Eddie Curzon, the London director of business organisation the CBI, described the ULEZ as a “really positive step” but warned that “smaller firms can struggle to afford the switch to low-emission vehicles”.

City Hall said Transport for London is running a scrappage scheme to help the smallest businesses and charities switch to cleaner vehicles.

It also noted that people in London’s most deprived areas are more likely to suffer from poor air quality and are least likely to own a car.

The charge’s debut comes after two-thirds of teachers said they would support a ban on cars near school gates.

Support free-thinking journalism and attend Independent events

Their stance followed a Unicef report which claimed that some 4.5 million children – or one in three – were growing up in towns and cities in the UK with unsafe levels of particulate pollution.