Ultra low emission zones should be introduced across the whole country after new research linked London's scheme to improved lung growth in children, a leading health charity has said.

Scientists led by Queen Mary University of London monitored the lung health of more than 3,400 children aged between six and nine during annual school visits from 2018 to 2022.

Children from 84 primary schools in London and Luton took part in the research, with Luton used as a comparison because it has a similar mix of traffic pollution but did not have a clean air zone.

Researchers examined how changes in air quality affected children's lung development after ULEZ was introduced by the mayor of London back in 2019.

Before the scheme came into force, initial measurements showed children in London had significantly smaller lung capacity than those in Luton.

But over the five-year study, researchers found lung growth among children in London accelerated, with their lung size and health becoming comparable with children in Luton.

The researchers said the improvement in children's lung growth was strongly linked to improvements in air quality following the introduction of ULEZ.

The findings were published on Tuesday in The Lancet Public Health.

ULEZ has been controversial since it was introduced by Sadiq Khan in 2019, with supporters saying it has helped cut air pollution and critics opposing charges for drivers of non-compliant vehicles.

But Sarah Sleet, chief executive of Asthma + Lung UK, said the research, published on Tuesday, provided “hard evidence” that low emission zones can help reverse the damage caused by air pollution to children’s lungs.

“ULEZ can spark fierce political debate, but this study replaces the polarised opinions with hard evidence,” she said.

“Air pollution damages kids’ lungs, and low emission zones can reverse the harm.”

The scheme was designed to improve air quality by reducing pollution from older, more polluting vehicles, including levels of nitrogen dioxide.

Drivers of vehicles that do not meet minimum emissions standards must pay a £12.50 daily charge to enter the zone.

Critics argue that the £12.50 daily charge acts as a "tax on the poor”, heavily impacting low-income workers, small business owners and tradespeople who rely on older vans and cars for work, while others questioned the effectiveness of the scheme in improving air quality.

But, Ms Sleet said the new evidence gives a “real cause for hope” that children with already damaged lungs can recover.

“Children’s lungs are still developing, making them especially vulnerable to the harmful effects of air pollution. They breathe faster than adults and often breathe in air closer to sources of pollution in their everyday lives, such as vehicle exhausts often being at pram height,” she added.

“Reducing their exposure to toxic air, lowers their risk of developing life-limiting lung conditions like asthma, Chronic Obstructive Pulmonary Disease (COPD) and lung cancer.

“The ULEZ has been a world-leading public health success and should be replicated in urban areas across the country. There is no good justification for children living in other UK cities to suffer stunted lung development when we know clean air zones work.

“The study authors have provided the evidence, now it’s up to local and national leaders to take action. Seventy years on from the first Clean Air Act, politicians can – and should – take steps to protect countless children from the suffocating grip of air pollution.”