Air pollution could be the cause of up to a third of new cases of childhood asthma in Europe, according to a new study.
The Barcelona Institute for Global Health says more than 66,000 cases could be prevented every year if countries adhered to the maximum pollution levels recommended by the World Health Organisation.
The study involved more than 60m children in 18 European countries including the UK where about 1.1 million youngsters are believed to suffer from the condition.
Haneen Khreis, lead author of the study and a researcher at the Texas A&M Transportation Institute in the US, said: 'In the past two years several analyses on air pollution and onset of childhood asthma have emerged, strengthening the case from different research teams that air pollution is contributing substantially to the burden of paediatric asthma.
'Largely, these impacts are preventable and there are numerous policy measures which can reduce the ambient levels of, and children's exposures to, outdoor air pollution.
'We can and should do something about it.'