Rishi Sunak has “put decades of progress on clean air into reverse” and now risks “stunting the lungs” of London’s children by failing to support the expansion of the capital’s ultra-low emissions zone, Sadiq Khan has said. Ahead of the clean air scheme’s rollout to all boroughs in the capital on Tuesday, the London mayor issued a stark warning to Sunak who he said risked going down in history as the prime minister who “had the chance to save lives but refused to take it”. Khan, who has accused the government of weaponising air pollution and climate change to win votes, has urged ministers to provide financial support for his policy, and the accompanying scrappage scheme, as it does for some other cities in England. The government has given financial assistance to Birmingham, Bristol and Portsmouth to help fund their clean air zones but has refused to support London’s scheme, arguing that powers over transport and air quality are devolved to the capital. Nearly 700,000 car drivers in Greater London face paying the £12.50-a-day Ulez charge from Tuesday when it is applied to all roads in the capital for the first time, according to figures obtained by the RAC, despite criticism that the move heaps financial pressure on struggling households. After opposition to the Ulez expansion was credited by the Tories for their narrow byelection victory in Boris Johnson’s former west London seat of Uxbridge and South Ruislip last month, Sunak delayed and, in some cases, abandoned green policies that impose a direct cost on consumers. However, Khan has argued that air quality in the capital is a health emergency – with about 4,000 Londoners dying prematurely due to causes linked to pollution in 2019, with the greatest number of premature deaths in outer London, according to Imperial College research. More than 500,000 Londoners live with asthma and are more vulnerable to the impacts of toxic air, with over 50% living in outer London boroughs, every one of which exceeds World Health Organization’s recommended guidelines for NO2 and PM2.5 pollution. Khan told the Guardian that he visited children’s hospitals after the death of nine-year-old Ella Kissi-Debrah, the first person to have air pollution listed as a cause of death at an inquest in the UK, and met ill children struggling to breathe as a result of air pollution. “Rishi Sunak has been shown to have been irresponsible and hypocritical,” he said. “What does he have to say to the parents of all those children with asthma who can’t breathe? Why is it OK to give financial support to clean air zones around the country but not London? “He could be the prime minister who puts a decade of progress on clean air in London into reverse. If he does, he will go down in history as the polluting PM who had the chance to save lives but refused to take it, stunting our children’s lungs in the process.” Khan added: “I’m not saying clean air zones are right for every part of Britain. But I know what the scientists, health practitioners and other experts tell me about our city and London has such toxic air, nothing else will fix it as fast or effectively. “I trust in Londoners and that they will understand how difficult this decision was but also how necessary it was. There are lives on the line – lives in my hands. I don’t want future generations to ask why we knew we what we did, had the opportunity to act and didn’t.” The government considered using legal powers to block the expansion, but ministers were said to have dropped the plan after receiving legal advice it would probably fail if challenged in court. The Labour leader, Keir Starmer, has previously said Khan “had to take action” due to the legal requirement on him to improve London’s air quality, and that the mayor was “between a rock and a hard place on this”. A £160m scheme which is run by Transport for London (TfL) enables the capital’s residents, small businesses, sole traders and charities scrapping non-compliant cars to claim grants to help cover the cost. After facing criticism for not doing enough to help Londoners affected by the transition, TfL expanded the eligibility for the scheme earlier this month from those on benefits to all households. It offers a £2,000 cash payment to persuade people to take their old polluting car to a scrapyard. To comply with Ulez standards, petrol cars must generally have been first registered after 2005, while most diesel cars registered after September 2015 are also exempt from the charge. Those riding motorbikes that do not meet the standards must also pay to enter the zone. The new London-wide zone also includes Heathrow airport for the first time, meaning drivers of older, more polluting cars making a one-off visit to the capital to fly or collect arriving passengers will also be hit by the scheme. A Tory party spokesperson said: “The Labour mayor of London is going out of his way to raise taxes on hardworking people by pressing ahead with his crippling Ulez tax – with full backing from Keir Starmer and his frontbench. “The Ulez expansion is not necessary. Sadiq Khan and the Labour party should listen to Londoners and scrap the expansion immediately.”