Asthma is estimated to affect 334 million people worldwide and numerous studies show that the prevalence of childhood asthma has increased significantly since the 1950s.
The reason for this increase is largely unknown, but experts believe it is due to changes in environmental exposures including air pollution.
This study, published in Environment International, is the largest and most up-to-date synthesis of scientific evidence on the relationship between air pollution caused by road traffic and the development of childhood asthma.
The authors reviewed more than 4,000 epidemiological studies published between 1999 and September 2016, and analyzed data from 41 of these epidemiological studies (many of them published in the last two years) that met the inclusion criteria for the meta-analysis.
Haneen Khreis, a researcher at the University of Leeds and the first author of the publication, concludes that “thanks to the analysis carried out in this study, in which data from multiple studies are combined, we can affirm that there is an association between exposure to air pollution and the development of childhood asthma ”.
World health problem
Specifically, the review includes exposure to nitrogen dioxide (NO2), black carbon or soot, and PM2.5 and PM10 airborne particles emitted by traffic during childhood and subsequent development of asthma.
"Our analysis shows that the strongest effects are associated with exposures to black carbon, a specific marker in vehicle tailpipes, and a diesel-related pollutant, but more research is needed to draw definitive conclusions, including exploration from pollutants that go beyond the tailpipes, "according to Khreis.
Today, many cities in Europe are dominated by diesel and there is an urgent need to reduce their emissions.
"Air pollution has a great impact on the health of children," says Mark Nieuwenhuijsen, coordinator of the study and director of the Urban Planning, Environment and Health Initiative at ISGlobal.
"Exposure to air pollution is a world-class problem and we must act now," he concludes.