Vigorous physical activity promotes lung growth in children, but these benefits are reduced by ozone pollution, according to new research presented at the ATS 2026 International Conference. The findings suggest that the health benefits of exercising at levels recommended by the World Health Organization may be limited by environmental conditions.
The study is among the first to examine how intense exercise and long-term ozone exposure interact to influence lung development in children. The findings suggest that, if environmental factors aren't addressed, children in more polluted areas may not be able to gain the same developmental health benefits from physical activity as their peers in cleaner environments, the study's authors said.
The main message is that physical activity and environmental health are closely connected. Encouraging children to be active is essential, but ensuring they grow up in clean, healthy environments is equally important."
James Scales, PhD, first author, senior research fellow, Queen Mary University of London
Supporting lung development in children is important because lung function in childhood is strongly linked to respiratory health later in life.
For the study, researchers analyzed data gathered on more than 3,400 children age 6 to 9 over four years as part of the Children's Health in London and Luton (CHILL) study. They compared data on the children's activity levels and lung growth with residential exposures to different types of air pollution.
A key finding was that, while vigorous physical activity showed a clear association with lung function, moderate activity did not. This suggests that the intensity of exercise matters for children's respiratory health. The team also found that ozone, a reactive gas that can irritate airways, was more important than particulate pollution in limiting the benefits of exercise.
"This fits with what we know about ozone's biological effects during exercise, that it has an irritant effect on the airways when breathing rates increase and more ozone reaches the lungs," Dr. Scales explained.
The findings could help support policies aimed at reducing ozone-forming emissions, he noted. They also suggest that environmental conditions should be considered when developing physical activity guidelines.
Next, researchers are planning follow-up studies to investigate whether there are specific thresholds for ozone exposure that trigger increased risk. They also hope to explore the short-term effects of ozone exposure on children's respiratory health.
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