City mayors representing more than 17 million people across the UK are urging Boris Johnson to commit to tougher air pollution targets after the inquest into the death of nine-year-old Ella Kissi-Debrah. The cross-party group, including the Labour mayor of London, Sadiq Khan, and the Conservative mayor of the West of England combined authority, Tim Bowles, have signed a joint letter along with city leaders from Liverpool, Manchester, Sheffield and the North of Tyne to urge Boris Johnson to enshrine in law a commitment to achieve World Health Organization air pollution guidelines by 2030. Ella’s mother, Rosamund Kissi-Debrah, signed the letter after a coroner ruled that illegal levels of air pollution had caused the death of her daughter in 2013. She called on the prime minister to act immediately to protect the lives and wellbeing of other young people across the country. “We need to take action now which will have long-term benefits,” she said. “People act as though we have time – we don’t have time because children are continuing to actually die.” The letter, which has also been signed by a range of business leaders, is calling for a £1.5bn boost to government spending on measures to improve air quality across the UK and for WHO targets to be included in the delayed environment bill. According to research by UK100, a group of more than 100 local authorities that coordinated the letter, the money could fund the removal of nearly half a million of the most polluting cars and vans from the road and incentivise people into cleaner vehicles, public transport, cycling and walking. Polly Billington, Director of UK100, said: “We cannot wait any longer to prevent more tragic deaths like Ella’s. Forty-thousand people die prematurely in the UK every year from air pollution. We need to act with the fierce urgency of now, not just to serve Ella’s memory, but to prevent more needless loss of life.” A growing body of research underlines the devastating impact air pollution – both indoors and outdoors – is having on the nation’s health. Recent studies suggest it may be damaging every organ in the body, with effects including heart and lung disease, diabetes, dementia, reduced intelligence and increased depression. Children and unborn babies may suffer the most. Earlier this week it was revealed that small increases in air pollution are linked to an increased risk of irreversible sight loss from age-related macular degeneration. Another recent report revealed that home wood burners triple the level of harmful particulates inside the home as well as creating dangerous levels of pollution in the surrounding neighbourhood. More than a third of local authorities in the UK have areas where the level of PM2.5 – one of the most dangerous toxic particles – exceeds World Health Organization limits. Research from 2017 showed that every borough in London exceeded WHO limits. In the letter the city leaders call for a clear post-Brexit commitment to WHO air pollution targets in the delayed environment bill. Campaigners and regional leaders fear that, without a cast-iron guarantee from government, environmental protections may be watered down now that Britain has left the EU and that progress on tackling air pollution could be jeopardised. Khan said Ella’s death must be a turning point in a national effort to clean up the UK’s air. The mayor of London said: “Including WHO recommended limits in the environment bill will be one of the most effective ways of ensuring other families do not have to suffer the same heartbreak as Ella’s have … Ministers must now learn the lessons from the coroner’s conclusion in Ella’s case and do more to tackle the deadly scourge of air pollution in London and across the country.” Andy Burnham, the mayor of Greater Manchester, said air pollution was an injustice that hit the poorest hardest, contributing to at least 1,200 deaths a year in his region. Burnham said Greater Manchester had a comprehensive package of measures including the largest clean air zone outside London to tackle the issues, but added: “We need concrete commitment from national government to provide sufficient funds to support those vehicle owners, many of whom live in the communities most affected, who have made previous vehicle choices in good faith.”