Up to 11 percent of new childhood asthma cases could be prevented each year if European countries complied with current World Health Organization (WHO) air quality guidelines, according to a study of 18 European countries co-led by Texas A&M Transportation Institute Associate Research Scientist Haneen Khreis, who is also on the Center for Advancing Research in Transportation Emissions, Energy, and Health (CARTEEH) research team.

Overall, 33 percent of new asthma cases in the 18 European countries studied can be attributed to air pollution levels. The study, led by Khreis and including researchers from the Barcelona Institute for Global Health (ISGlobal), was published recently in the European Respiratory Journal.

Asthma is the most common chronic disease in children. Emerging evidence suggests that exposure to air pollution increases the risk of developing this respiratory disease during childhood. The new study estimates the burden of new childhood asthma amongst 63.4 million children. The study focuses on three key pollutants: PM2.5 (33%), NO2 (23%) and black carbon (15%).

The study used census population data from the 18 European countries and the incidence rates of asthma in children obtained from the Global Burden of Disease study database. Exposure to the different pollutants was calculated using a harmonized European statistical model (land use regression) based on multiple measurements in Europe.

Two different scenarios were used to estimate the burden of childhood asthma: one based on the maximum air pollution levels recommended by WHO air quality guidelines and a second using a reference to the lowest air pollution levels recorded among 41 previous studies.

The analysis for the first scenario indicates that 66,600 childhood asthma cases, 11% of the total cases recorded, could be prevented each year if the 18 countries studied complied with the WHO air quality guideline for PM2.5. Compliance with the NO2 guideline was estimated to prevent 2,400 asthma cases each year.

According to the results of the second scenario, 33% of new childhood asthma cases – more than 190,000 annual cases – could be prevented were the 18 countries to meet the lowest levels of PM2.5 recorded by previous studies.

The estimates of this study are in line with two previous studies conducted in the United Kingdom and a Global analysis published earlier this year.

“Our findings reinforce the case that air pollution is contributing substantially to the burden of pediatric asthma,” Khreis noted. “This new analysis is a call for urgent action. These impacts are preventable. We can and should do something about it.”

The 18 European countries studied are Austria, Belgium, Denmark, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Lithuania, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Countries from Eastern Europe were not included due to the lack of air pollution exposure data in the region.

Reference

Haneen Khreis, Marta Cirach, Natalie Mueller, Kees de Hoogh, Gerard Hoek, Mark J Nieuwenhuijsen and David Rojas-Rueda. Outdoor Air Pollution and the Burden of Childhood Asthma across Europe. Eur Respir J 2019; in press https://doi.org/10.1183/13993003.02194-2018