One in five new childhood asthma cases in the UK could be linked to traffic pollution, new research suggests.
Exposure to nitrogen dioxide, which is mainly emitted from road transport, appears to be a “substantial” risk factor for the condition, according to a study in The Lancet Planetary Health journal.
Researchers estimate that four million new cases of childhood asthma globally – 13% of those diagnosed – could be attributable to nitrogen dioxide pollution every year. In the UK, they suggest 19% of new childhood asthma cases every year are attributable to nitrogen dioxide pollution.
This figure rises to 23% in Manchester and 29% in London.
“Our study indicates that policy initiatives to alleviate traffic-related air pollution can lead to improvements in children’s health and also reduce greenhouse gas emissions,” said lead author Dr Ploy Achakulwisut, from George Washington University, in the US.
“Recent examples include Shenzhen’s electrification of its entire bus fleet and London’s Ultra-Low Emission Zone congestion charges.”
It is thought that pollution from traffic may damage airways, leading to inflammation and the development of asthma in children who are genetically predisposed to the condition.
While it is not clear which pollutant in traffic air pollution is responsible, previous research has suggested exposure to nitrogen dioxide is key.
Traffic emissions can contribute up to 80% of ambient nitrogen dioxide in cities.
The researchers used global data on nitrogen dioxide concentration and asthma incidence to estimate the number of new cases in children aged one to 18 years old which could be related to traffic pollution.
Out of the 194 countries studied, the UK had the 24th highest proportion of new childhood asthma cases which could be attributable to traffic pollution. South Korea topped the list, with nearly one third (31%) of new diagnoses linked to nitrogen dioxide exposure.
Dr Samantha Walker, Director of Policy and Research at Asthma UK, told HuffPost UK polluted air is affecting an estimated half a million children with asthma in the UK and putting them at risk of having a potentially life-threatening asthma attack.
“Worryingly, this study confirms existing research which shows that children who are breathing in toxic air from traffic fumes have stunted lung growth and are at risk of developing asthma,” she said.
The charity is calling on the Government to commit to targets that reduce toxic air across the UK to the legal levels recommended by the World Health Organisation, “so that future generations can breathe clean air.”