Air pollution causes a third of childhood asthma cases

Around 1.1 million children are believed to suffer from asthma in the UK. It is thought that pollution from traffic can damage airways, leading to inflammation and the development of asthma in children who are genetically predisposed to the condition.

The study, led by the Barcelona Institute for Global Health (ISGlobal), looked at asthma in 63,442,419 children across 18 European countries, including the UK, in 2016.

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They compared asthma incidence rates with estimations of levels of exposure to pollutants in more than 1.5 million square km areas in 2010, which are often traffic-related in urban areas. Finally, they estimated how rates could be affected if levels were reduced in two different scenarios.

They found that 11.4 per cent of the total cases of asthma (66,567) could be prevented each year if countries adhered to the maximum air pollution levels recommended by the World Health Organisation (WHO) for the tiny particles known as PM2.5. This equates to more than 10,000 cases in the UK being prevented each year.

But only 0.4% (2,434 cases) across the 18 countries would be prevented with the reduction of another pollutant, nitrogen dioxide (NO2), which is a better marker of traffic sources.

The researchers said they believe the guidelines are outdated and need to be lowered. If the 18 European countries went further, tens of thousands more cases of childhood asthma could be avoided, the researchers predict.

In the UK for instance, 44,895 cases (29% of the UK total) could be avoided if the country reduced air pollution to the lowest levels recorded in 41 previous studies. Similarly, 191,883 cases (33%) could be avoided each year across the 18 European countries in the study.

For the N02 pollutant, 135,257 (23%) cases could be stopped if the countries adhered to the lowest levels – 40,000 of which were in the UK (26% of the UK total).

If a third pollutant, black carbon, was reduced to the lowest level, 19,139 cases in the UK and 89,191 cases across the 18 countries could be avoided annually.

Professor Mark Nieuwenhuijsen, an author of the study from the Barcelona Institute for Global Health, said “major lifestyle changes” in the UK would be needed to reach the lowest levels, as recorded in Scandinavian countries.

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He said: “A lot of the air pollution we have comes from cars, residential cooking and heating, industry and ports, so what you need to get rid of is the fossil fuels that produce all this pollution.

“And, besides that, what you also might want to look at is a reduction of cars in cities because, even if you get electric cars, if they run on renewable energy you still have particulate matter coming from the brakes, tyres and the wear and tear of the car.

“It will reduce NO2 levels, but only 50% or so of the PM2.5 levels.

“So you are also looking towards a reduction of cars and a move towards public transportation, cycling or walking.”

The study, published in the European Respiratory Journal, concluded: “Our estimates are larger than previous documentation and underline the urgent need to reduce children’s air pollution exposure across Europe.”

Lead author Haneen Khreis, lead author of the study and a researcher at the Texas A&M Transportation Institute, said: “Only 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.”