Nearly 11% of new childhood asthma cases could be prevented each year if only European countries complied with WHO air quality guidelines. But an even more shocking number, 33%, of all new asthma diagnoses in children are due to poor air quality, says a new study.
The study, conducted by the Barcelona Institute of Global Health, is the latest in focusing on asthma diagnoses among children. Asthma is currently the most common chronic disease in children.
According to the study, poor air quality could be the causes of nearly one-third of the 63.4 million cases of childhood asthma in 18 European countries. Researchers use population data and national-level figures for childhood asthma and the levels of pollution children are exposed to depending on where they live.
“A considerable proportion of childhood asthma is actually caused by air pollution, particularly PM2.5,” said Dr. Mark Nieuwenhuijsen, a co-author of the research.
WHO guidelines state that levels of PM2.5 should not exceed an annual average of 10 μg/m3, and levels of NO2should not exceed an annual average of 40 μg/m3.
The study concludes that if countries were to stay within these limits they could avoid 66,600 new cases of childhood asthma – or 11% of all cases. If air pollution levels were able to be lowered to the lowest ever recorded in studies – a level recorded in Germany for PM2.5 and in Norway for NO2 – then 33% of all new childhood asthma cases could be avoided.
“The analysis showed that, while meeting the WHO recommendations for PM2.5 would imply a significant reduction in the percentage of annual childhood asthma cases, that is not the case with NO2, where 0.4% of the cases would be prevented,” says David Rojas-Rueda, one of the lead scientists on the study. “Therefore, our estimations show that the current NO2 WHO air quality guideline value seems to provide much less protection than the PM2.5 guideline. We suggest that these values require update and lowering to be better suited in protecting children’s health.”
Previous studies of childhood asthma in relation to air pollution in the UK had similar findings. One study found that the percentage of annual childhood asthma cases attributable to NO2 was 22%. Another study estimated an annual 4 million new childhood asthma cases could be attributed to NO2 pollution.
“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 pediatric asthma”, said Haneen Khreis, lead author on the study. “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.”