London’s ultra-low emission zone will be expanded across the entire capital from next August, a move that the mayor said would bring cleaner air to 5 million more residents.

Drivers of older, polluting cars will have to pay £12.50 a day to use their vehicle across Greater London from 29 August 2023.

An improved £110m scrappage scheme will be introduced to help vulnerable people and small businesses, and there will be more buses in the suburbs.

The mayor, Sadiq Khan, announced the start date after a summer consultation on the scheme. It has been welcomed by green groups, clean air campaigners and some businesses, although Conservatives have opposed the charge and said most people in outer boroughs do not want it.

Khan said the capital’s toxic air, and the climate emergency, made it a public health imperative, and that revenue raised would go into public transport.

New ultra-low emission zone map

Announcing the decision at Bonus Pastor school in Lewisham, an area with dangerously poor air quality, Khan said: “The latest evidence shows that air pollution is making us sick from cradle to the grave. Londoners are developing life-changing illnesses such as cancer, lung disease, dementia and asthma. And it’s especially dangerous for children.”

He said the zone, which was expanded from the heart of the city to boroughs within the north and south circular roads last October, had been “transformational”, reducing harmful pollution levels by almost a half in central London. “Expanding the Ulez London-wide will mean 5 million more people will be able to breathe cleaner air and live healthier lives,” he said.

Khan said the rising cost of living was a major consideration and that the £110m scrappage scheme would help people who most needed it to scrap or retrofit non-compliant vehicles.

Alex Williams, Transport for London’s chief customer and strategy officer, said the scheme would offer “unparalleled support”, extending the grace period for some types of vehicles and groups, including disabled people, and offering more free bus passes.

He said it would be “complemented by significant improvements to the outer London bus network, making public transport a more attractive alternative to the car”.

While London has struggled financially, TfL and the mayor say the Ulez expansion is designed to get the most polluting vehicles off the road rather than to raise revenue, with compliance now at 94%.

About 15% of vehicles driving in outer London boroughs would currently be liable for the charge – 160,000 cars and 42,000 vans entering the zone daily, according to TfL estimates.

However, it expects tens of thousands of drivers to switch to compliant vehicles or other modes before the zone is extended. Most petrol cars registered after 2006 or diesel cars from 2016 are exempt.

Rosamund Adoo-Kissi-Debrah, a clean air campaigner whose daughter Ella died of respiratory diseases partly caused by pollution, said it was a “step in the right direction”. She said: “When we had the inquest, we got the experts in Ella’s case to give some recommendations and all of them agreed Ulez expansion was something that needed to be done to clean up the air in London. Clean air should be a human right.”

Muniya Barua, the deputy chief executive at BusinessLDN, welcomed the move but said the mayor and TfL’s next step should be to accelerate plans for a smarter road pricing scheme. “With congestion costing the economy over £5bn a year and a 27% reduction in car miles required to hit our net zero targets, this has to be a priority.”

Conservatives in the Greater London Assembly condemned the move and warned it could still be stopped by a legal challenge, with about 60% of respondents to the consultation opposed to the expansion.

Nick Rogers, the GLA Conservatives’ transport spokesperson, said: “Now is not the time to hammer Londoners with a £12.50 daily cost of living charge. Residents have made their views very clear to the mayor: they do not want the Ulez expansion.”