The high court has granted a new inquest into the death of a schoolgirl who died of an asthma attack thought to be linked to illegal levels of air pollution near her south London home.

The family of Ella Kissi-Debrah believe air pollution should be cited as a cause of the nine-year-old’s death, in what would be a legal first that could pile pressure on the government to tackle the problem.

In January the attorney general granted the family leave to apply for a new hearing after receiving fresh evidence that for the first time linked Ella’s death to air pollution.

On Thursday the high court said a new hearing should take place. Ruling with two other judges that the conclusions of the original inquest in 2014 should be quashed, Mark Lucraft QC said: “In our judgment, the discovery of new evidence makes it necessary in the interests of justice that a fresh inquest be held.”

He said the family’s lawyers had argued the new evidence demonstrated there was an “arguable failure” by the state to comply with its duties under the European convention on human rights, which protects the right to life.

If air pollution is now cited as a contributory cause of death, it could open the door to more cases against the authorities for failing to clean up the UK’s air.

Ella lived 25 metres from the South Circular road in Lewisham. She died in February 2013 after three years of seizures and 27 visits to hospital for asthma attacks.

Ella’s mother, Rosamund Kissi-Debrah, said she was delighted by the court’s ruling. “[I] look forward to finally getting the truth about Ella’s death,” she said. “The past six years of not knowing why my beautiful, bright and bubbly daughter died has been difficult for me and my family, but I hope the new inquest will answer whether air pollution took her away from us.

“If it is proved that pollution killed Ella then the government will be forced to sit up and take notice that this hidden but deadly killer is cutting short our children’s lives.”

Air pollution is thought to cause or contribute to as many as 40,000 deaths a year in the UK, especially among people with respiratory problems.

Nearly 40 million people in the UK live in areas with illegal levels of air pollution, and judges have repeatedly condemned the government for failing to tackle levels of nitrogen dioxide from diesel vehicles. Air pollution has been measured at illegal levels in 37 out of 43 zones across the country.

Ella’s family believe the government’s repeated failure to reduce air pollution breached Ella’s right to life under article 2 of the European convention on human rights. Levels of nitrogen dioxide and particulate pollution around the South Circular breached legal limits for much of the time Ella was ill.

Jocelyn Cockburn, a partner at the law firm Hodge Jones & Allen who represents Kissi-Debrah, said: “A new inquest will … mean the government and other public bodies will have to answer difficult questions about why they have ignored the overwhelming evidence about the detrimental health impact of air pollution and allowed illegal levels to persist for more than a decade. There is now momentum for change and it is fundamental that air pollution is brought down to within lawful limits.”

In a report for the family that was presented to the attorney general last year, Prof Stephen Holgate, an expert on air pollution, suggested Ella might have survived if the air pollution around her home had not been so high.

“The dramatic worsening of her asthma in relation to air pollution episodes would go a long way to explain the timing of her exacerbations across her last four years,” he said. “There is a real prospect that without unlawful levels of air pollution Ella would not have died.”

Caroline Russell, a Green party member of the London assembly, said of the new inquest: “This is welcome news for Ella’s family who watched her health suffer during high-pollution episodes. They saw for themselves the horrifying link between bad air and severe childhood asthma. This is about Ella and all the other children living with life-threatening asthma.

“This could have huge implications for the public bodies who will no longer be able to escape the consequences of their inaction and it could open them to financial and legal risks.”