The mayor of London, Sadiq Khan, has promised to press ahead with a city-wide ultra-low emission zone to stop people “breathing poison” as he launched a £110m scrappage scheme to help replace polluting vehicles.

Ulez will be expanded to the Greater London boundary in August despite widespread opposition from borough councils, four of whom have threatened legal action.

Drivers of some older petrol vehicles and most diesels more than seven years old have to pay £12.50 a day to drive in London’s Ulez, which was launched in 2019 and expanded to cover the inner boroughs in October 2021.

About 15% of vehicles in outer London would be liable for the charge.

London’s expanded ultra-low emission zone

The owners of about 30,000 vehicles are expected to access payouts from the scrappage scheme, which opened on Monday on a first-come, first-served basis. Eligible drivers, including Londoners who have a disability or are on lower incomes, can get up to £2,000 cash, while charities, sole traders and small businesses can receive up to £9,500 to replace or retrofit their old, polluting vehicles.

Transport for London will also offer bigger inducements for people to switch from vehicle ownership entirely, including discounted rental for cars or bikes and cheaper public transport.

Khan launched the scrappage scheme at the Enfield distribution hub of the Felix Project, a charity that delivers surplus food from suppliers to hundreds of food banks and small community projects.

Speaking at the site, on an industrial estate beside the six-lane section of the A10, the mayor said: “It’s really important that we don’t dither or delay and take action to clean up the air.

“We’ve seen the benefits in central and inner London. Thousands made the transition to not using vehicles or going to cleaner vehicles.

“Here in Enfield, this borough, there are 150 premature deaths a year, 150 bereaved families a year, because of this deadly air. I don’t want anyone to come to our city and breathe in poison.”

About 94% of vehicles driving in the Ulez zone are now compliant, and do not pay a charge, compared with just 35% in 2017, when the scheme was announced.

The Felix Project had submitted concerns about widening Ulez in TfL’s consultation, with volunteers potentially deterred and van drivers charged while working.

Khan said the charity did “brilliant work” and had also “been on a journey” to ensure all but three of their 45-strong fleet were Ulez-compliant. “That means their drivers are breathing clean stuff, but also when they go around the city they’re not putting out poison. That’s good for their drivers, their volunteers and good for London.”

However, a number of boroughs have expressed concerns about the plans, while a majority of respondents to TfL’s consultation oppose the scheme. Four London boroughs – Bexley, Bromley, Hillingdon and Harrow – have announced plans to take legal action to force a possible judicial review, while others have threatened to block the installation of cameras to enforce the the extend Ulez.

Khan urged the four Conservative boroughs, which were “using taxpayers funds” for legal action, to lobby the government instead, and said he was confident of defending any court case. “It’s unacceptable that there are 4,000 deaths a year. The easy thing to do would be to kick the can down the road – but I’m not willing to delay,” said the mayor.

He said polling showed the policy was “representing the silent majority” and likened it to the controversy over banning smoking in public buildings 15 years ago. “In a few years time we’ll be looking back, thinking it’s ridiculous that you could have vehicles driving around our city churning out poison,” Khan said.