It may have been his toughest meeting yet. A delegation of mothers from all over the world, all of whom had seen their own children suffer health damage from air pollution, met the Cop26 president, Alok Sharma, on Friday morning to demand an end to fossil fuel financing.

The delegation was led by Rosamund Adoo-Kissi-Debrah, who lost her nine-year-old daughter, Ella, to severe asthma that was officially linked to air pollution in London. She was joined by Dr Maria Neira, the director of public health at the World Health Organization (WHO), and other mothers from India, Brazil, South Africa, Poland and Nigeria, to present a letter to Sharma.

“Lots of words and no action – and toxic pollution on our streets – is fuelling a public health crisis that is making our kids sick and threatening their futures,” said Kissi-Debrah. “We need urgent action now.”

“We put Alok Sharma on the spot and played him a soundscape of children fighting to breathe,” she said. “He genuinely looked moved – we think he shed a tear or two.” Sharma was joined by his wife and daughter at the meeting.

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The delegation represented almost 500 parent groups from 44 countries and may be the biggest parent mobilisation on any issue in history.

More than 90% of children around the world breathe toxic air today, with fossil-fuel burning largely responsible. Coal, oil and gas are responsible for 8.7 million premature deaths a year, one in five of all deaths.

The parents’ letter said: “There are already more than enough fossil fuels to dangerously heat our planet beyond 1.5C and keep poisoning our children’s air.” It calls on the world’s leaders to listen to the International Energy Agency, which warned in May that there should be no new oil or gas exploration or coal-fired power stations.

“We make decisions every day for our children’s long-term future, and here at Cop26, so do you,” the letter said. “You have a unique responsibility and opportunity to protect all children, present and future.”

The women in the delegation have all seen their own children suffer as a result of air pollution caused by fossil fuels. Bhavreen Khandhari, from Warrior Moms, a group of mothers fighting air pollution in India, lives in Delhi, which has some of the dirtiest air in the world. “For children to have the lungs of a smoker by their teens, through no fault of their own, just by breathing air is absolutely unacceptable,” she said.

Xoli Fuyani, from Our Kids’ Climate in South Africa, said: “I implore Cop delegates to think of a child they know, and act in their interests. Children in the global south are already feeling the brunt of the climate crisis. Why are governments still subsidising the search for more fossil fuels with public money every year?”

Kamila Kadzidlowska, from Rodzice Dla Klimatu in Poland, said: “My children cough and suffer respiratory diseases because of toxic coal pollution. I can’t stop them getting sick unless our leaders make bold choices. This Cop26 needs to consign new fossil fuels to history.”

Maria Neira of the WHO said: “The day I joined the movement of mothers for clean air, I knew we would be able to turn the tide on climate change, as there is nothing stronger than the love of a mother for her children. Air pollution from the burning of fossil fuels is killing our children, and there is nothing, and I mean nothing, we won’t do to protect our children. So join us, or get out of our way, as we end the era of fossil fuels.”

More than 40 nations at Cop26 have pledged to end the burning of coal, though campaigners said the timescales for the phase out were too long and some of the world’s biggest coal-dependent economies were missing from the deal, including Australia, China, India and the US.

A group of 20 nations also pledged to stop all funding of fossil fuel projects abroad and divert about $8bn of spending to green energy instead from next year. However, China and Japan, two big funders of fossil fuel development around the world, shunned the initiative.

After handing over the letter, the group joined the Fridays for Future demonstration through the centre of Glasgow. Thousands of young people were expected to attend, with activists including Vanessa Nakate and Greta Thunberg due to speak during the afternoon.

About 10,000 protesters walked through the city to coincide with Youth and Public Empowerment Day at Cop26. Children were on the streets with their parents, classmates and teachers, demanding world leaders do more to stop polluters and save the planet from catastrophic rising temperatures.

A larger crowd is expected on Saturday for the global day of action for climate justice, with protests expected in about 200 cities around the world.