London — A court ruling could lead to a 9-year-old London girl becoming the first person to have "air pollution" listed as a cause of death in the United Kingdom, her legal team says.

Ella Kissi-Debrah died in 2013 after three years of having severe asthma attacks, her mother Rosamund Kissi-Debrah told CBS News Friday. When Ella died, the cause of her death was determined to be a severe asthma attack that led to respiratory failure. New evidence, her legal team claims, shows her death was caused by pollution in the air she breathed.

"When she was alive, we couldn't get to the bottom of what was triggering her asthma, so I thought I would give it my best shot (to find out), as her mother, although she's no longer here," Kissi-Debrah told CBS News. "I didn't have any plans or any ideas what I was going to find out, all I knew was it was to do with something in the air."

Ella Kissi-Debrah The Ella Roberta Family Foundation

A report put together for Kissi-Debrah by Stephen Holgate, the former chair of the U.K. government's advisory committee on air pollution and a professor at Britain's University of Southampton, found that Ella's asthma attacks coincided with years of air pollution levels near her home that were above the legal limit. On the basis of that report, on Thursday, the High Court allowed Ella's previous cause of death to be scrapped and a new inquest to be opened.

Get Breaking News Delivered to Your Inbox

"There is a real prospect that without unlawful levels of air pollution Ella would not have died," the report was cited as saying in a memorandum provided by Kissi-Debrah's legal team. If a new cause of death is linked to air pollution, Ella's lawyers argue the British government could have failed to comply with its duties under the European Convention on Human Rights.

The World Health Organization estimates that around 4.2 million premature deaths a year are the result of air pollution, much of which comes from cars and trucks. In the U.K., regulations came into effect in 2010 requiring the government to keep this pollution below certain levels, but limits have been consistently breached, despite some efforts by authorities.

Air pollution is widely acknowledged to be a trigger for asthma attacks, and "the dramatic worsening of (Ella's) asthma in relation to air pollution episodes would go a long way to explain the timing of her exacerbations across her last 4 years," Holgate's report is cited as saying.

"Whilst we are debating, there will be a child who is being rushed to hospital somewhere in the United Kingdom or in the United States or somewhere in the world," Kissi-Debrah told CBS News. "Now that one truly understands the impact of air pollution, and especially on children's lungs, the picture seems to be so very clear."

Ella lived near a busy street where pollution levels were consistently recorded at above the legal limit between 2010 and her death in 2013. A new inquest into her death means "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," her lawyers said in a statement.

"There is now momentum for change and it is fundamental that air pollution is brought down to within lawful limits," the statement continued.

Kissi-Debrah noted to CBS News that her daughter would be 15 years old if she were alive today, roughly the same age as teenage climate activist Greta Thunberg.

"What Greta is saying, my daughter is proving it," she said.