Cities Contribute To Asthma, Researchers Argue

FRIDAY, May 23, 2025 (HealthDay News) — Dirty, crowded urban environments can significantly increase a person’s risk of developing asthma, a new study says.

Cleaner, better-thought-out cities could ward off 1 of every 10 asthma cases, researchers reported recently in The Lancet Regional Health – Europe.

Asthma risk in both kids and adults is increased due to urban air pollution, dense development and limited green spaces, results show.

Cities built or altered to address these risks can help prevent asthma, researchers said.

“We have combined several environmental factors and described how they together affect the risk of developing asthma,” lead researcher Zhebin Yu, an assistant professor of environmental medicine at the Karolinska Institute in Sweden, said in a news release.

“This provides a better picture of environmental risks, as life in a city usually involves exposure to several environmental risk factors at the same time,” Yu continued.

For the study, researchers pooled data from 14 previous studies involving nearly 350,000 people living in seven European countries.

The data contained home addresses of each person, allowing the team to tie different environmental risks to specific cases of asthma. These risks included air pollution, outdoor temperatures and the level of urban density.

Nearly 7,500 people included in the study developed asthma as children or adults, and nearly 12% of asthma cases could be explained by environmental factors, results show.

That means that in a more favorable environment, about 1 in 10 people with asthma wouldn’t have developed the breathing disorder, researchers said.

“This is useful for politicians and others involved in urban planning. The method makes it possible to identify risk areas in existing urban areas, but it can also be used when planning future urban environments,” senior researcher Erik Melén, a professor of pediatrics at the Karolinska Institute, said in a news release.

Researchers next plan to examine blood samples from study participants to try and suss out how these environmental factors specifically affect asthma risk.

More information

The American Lung Association has more on asthma risk factors.

SOURCE: Karolinska Institute, news release, May 15, 2025