The high court has dismissed a legal challenge by five Conservative-led councils against the expansion of London’s ultra-low emission zone (Ulez). The zone, which the mayor of London, Sadiq Khan, said was vital to tackle toxic air, is due to be extended throughout the whole of Greater London at the end of August, making owners of the most polluting cars pay to drive. The outer London boroughs of Bexley, Bromley, Harrow and Hillingdon, along with Surrey county council, launched legal action in February. At the high court earlier this month, barristers argued that Khan had failed to adequately consult, overstepped his powers, and had provided a flawed £110m scrappage scheme. In his verdict today, Mr Justice Swift found that the legal basis on which Khan made the decision to expand the Ulez was sound and in line with previous decisions on charging within the capital. In a summary of his ruling, the judge said he was “satisfied that the mayor’s decision … was within his powers”, and that enough information was given for people who wished to respond to provide “informed responses”. The consultation on the scrappage scheme was “not in depth” but was “lawful”, he said. Khan immediately confirmed he would expand the zone as planned on 29 August, and extend the remit of the scrappage scheme to help more affected Londoners – including all those in receipt of child benefit payments. He said the current zone had already reduced nitrogen dioxide air pollution by almost half in central London. The mayor said: “The decision to expand the Ulez was very difficult and not something I took lightly, and I continue to do everything possible to address any concerns Londoners may have. “The coming expansion will see 5 million more Londoners being able to breathe cleaner air. “I’ve been listening to Londoners throughout the Ulez rollout, which is why from next week I am expanding the scrappage scheme to nearly a million families who receive child benefit and all small businesses with up to 50 employees. “Nine out of 10 cars seen driving in outer London on an average day are already compliant, so won’t pay a penny – yet will still see the benefits of cleaner air. Air pollution is an urgent public health crisis – our children are growing up with stunted lungs, and it is linked to a host of serious conditions, from heart disease to cancer and dementia.” Drivers of vehicles that do not meet the Ulez standards – typically petrol cars from before 2006 and diesels registered before 2015 – have to pay £12.50 a day when they enter the zone. Originally drawn up under the previous mayor, Boris Johnson, the Ulez launched in central London in 2019, and was expanded to draw about 4 million people into the zone, up to the North and South Circular roads, in October 2021. The planned expansion throughout Greater London has become a significant political issue, and was seen as the key factor in the Conservatives narrowly winning the Uxbridge and South Ruislip byelection last week. Conservatives in London said that they would continue campaigning to get the Ulez expansion scrapped. According to Transport for London, only about 6% of vehicles now entering the zone pay a fee.