The family of a nine-year-old girl whose death was linked to unlawful levels of air pollution have been given permission by the Attorney General to apply for a fresh inquest.
She died in February 2013 after three years of seizures and 27 visits to hospital for asthma attacks.
Lawyers say her original inquest in 2014 did not investigate the potential impact of air pollution, concluding that Ella's cause of death was acute respiratory failure caused by a severe asthma attack.
But an expert report by Professor Stephen Holgate, quoted in a submission to the Attorney General, concluded that it was likely that unlawful levels of air pollution contributed to Ella's fatal asthma attack.
The report, obtained in April 2018, said air pollution levels at the Catford monitoring station one mile from Ella's home "consistently" exceeded lawful EU limits over the three years prior to her death.
Prof Holgate - a leading expert in asthma and air pollution - found a "striking association" between Ella's hospital admissions and air pollution episodes.He concluded there was "a real prospect that without unlawful levels of air pollution Ella would not have died".
After the fresh evidence emerged, more than 170,000 people signed a Change.org petition set up by Ella's mother, calling for a fresh inquest.
Hodge Jones & Allen, who represent Rosamund Kissi-Debrah, said on Friday morning that Geoffrey Cox QC had given her permission to apply to the High Court to quash the first inquest and seek a second.
The Attorney General said: "I have received several representations about Ella's case, and acknowledge the wider interest that has been taken in it.
"However, I must assess the application based only on the facts of the case, and on whether there is enough new evidence available to merit reopening the inquest process.
"I have concluded that there is new evidence which may alter the substantial truth of Ella's death.
"I am therefore able to give my permission for an application to the High Court to request a new inquest, based on the evidential test being met."
An application will now be lodged and a judge will decide if a new inquest will take place.
If the family's request is granted, Ella may become the first person in the UK for whom air pollution is listed as the cause of death.
Ms Kissi-Debrah said: "Words cannot express how happy I am that the Attorney General has taken this decision and I would like to thank him for reaching his conclusion.
"Nothing will bring my beautiful, bright, bubbly child back, but now at least I may get answers about how she died and whether it was air pollution which snatched her away from us.
"Now I hope a new inquest will make those in power realise that our children are dying as a result of the air that they breathe.
"This cannot go on. Why is this not being taken more seriously by the Government?
"What do we need to do to make them prioritise our children's lives over convenience and the rights of people to pollute?"
Jocelyn Cockburn, partner at Hodge Jones & Allen, who represents Ms Kissi-Debrah, said: "This is a major step on the path to getting justice for this family which has been looking for answers into why Ella lost her life five years ago.
"An inquest will provide a better understanding of why she died and whether her death was avoidable.
"It will force the government and other bodies to account for their actions, and in many regards their inaction, on air pollution over this period.
"Air pollution is costing people's lives and those most vulnerable are children.
"There is a for need for more urgency into how air pollution is dealt with in urban areas to bring it within lawful limits as soon as possible."