The combination of air pollution, dense urban development and limited green spaces increases the risk of asthma both in children and adults. This is demonstrated by a new study conducted as part of an important collaboration of the EU led by researchers from the Karolinska Institute.
The study covers almost 350,000 people of different ages, 14 cohorts in seven European countries. The information on the housing addresses of each individual made it possible to link data on various environmental risks in the urban environment with individual people. The environmental exhibitions included were air pollution, outdoor temperatures and the level of urban density. The evaluation was based partly on satellite images that show gray, green or blue areas, that is, where there were buildings, green spaces or water.
“Previous studies have generally calculated the risk of an environmental factor at the same time. We have combined several environmental factors and describe how together they affect the risk of developing asthma. This provides a better image of environmental risk, since life in a city generally implies exposure to several environmental risk factors at the same time,” says the first author Zhebin Yu, a researcher and assistant professor at the Institute of Environmental Medicine in Karolinska Institute.
During the study period, almost 7,500 of the study participants developed asthma as children or adults. The researchers found that 11.6 percent of asthma cases could be explained by the combination of environmental factors. Or, to put it in another way, in a favorable environment, approximately one in ten people with asthma would not have developed the disease. The combination of air pollution, lack of green spaces and dense urban development was more relevant to the development of asthma.
“This is useful for politicians and others involved in urban planning. The method allows you to identify risk areas in existing urban areas, but can also be used by planning future urban environments,” says Erik Melén, professor of the Department of Research and Clinical Education, Södersjukhuset, and the last author of the study.
The next step for researchers is to examine the blood samples of some of the study participants. The objective is to identify its metaboloma, that is, a composite image of metabolism and body decomposition products. The purpose is to understand how external environmental factors affect the body, which could provide a better understanding of how asthma develops.
The study was carried out in the collaboration between several research groups within the framework of the expansion of the EU project. The researchers involved in the project are also investigating how the risk of other diseases such as stroke, heart attack, COPD and diabetes, is affected by individual exhibitions, that is, total exposure to many environmental factors.
The study was financed by the EU Horizon 2020 program (Exponse, no 874627), the Sweden Research Council, Forte (the Swedish Research Council for Health, Working Life and Welfare), the Swedish Heart-Lung Foundation and the Stockholm region, among others.