Study: ozone reduces exercise lung gains

James Scales and colleagues presented data on May 20 at the American Thoracic Society’s 2026 conference showing that ozone pollution can cut into the lung-growth gains children get from vigorous exercise. The research was based on 3,414 children ages 6 to 9 in the Children’s Health in London and Luton, or CHILL, study, a long-running project led by Queen Mary University of London. Researchers said vigorous activity was associated with better annual growth in lung function, but that benefit was reduced in children exposed to higher ozone levels. The findings were presented in Orlando during ATS 2026 and described in conference materials released May 20. ### What exactly did the researchers measure? James Scales, a senior research fellow at Queen Mary University of London, said the team combined annual activity and lung-function data with modeled air-pollution exposure. According to the conference materials and Healio’s report from the meeting, the children wore Actigraph accelerometers to measure physical activity, and researchers used spirometry to track forced expiratory volume in one second, or FEV1, and forced vital capacity, or FVC, over four years. (eurekalert.org) They also estimated annual residential exposure to ozone, particulate matter and nitrogen dioxide using high-resolution atmospheric models. The CHILL study itself follows more than 3,000 primary school-aged children in London and Luton to examine how traffic-related air pollution affects health and development, according to Queen Mary University of London. The cohort was set up to study children’s lung growth and respiratory health over time. ### How large was the exercise benefit before ozone entered the picture? (eurekalert.org) Healio reported that vigorous physical activity was significantly associated with greater annual growth in both FEV1 and FVC. Scales said every additional 10 minutes of daily vigorous activity was linked to roughly 10 mL greater annual growth in both measures, which could add up to about 40 mL over four years. He said that magnitude could be clinically meaningful because lower peak lung function has been linked to later respiratory risk. (qmul.ac.uk) ATS said moderate activity did not show the same clear association with lung growth. The conference release said the benefit appeared with vigorous activity, not with moderate activity alone, suggesting exercise intensity mattered in this dataset. ### Where does ozone fit into the result? ATS said ozone was the pollutant most clearly tied to reduced exercise-related lung gains. (healio.com) The conference release said particulate pollution did not show the same limiting effect, and Healio reported the effects of particulate matter were neutral or slightly positive in this analysis. Scales said the finding fits with what is already known about ozone’s airway effects during exercise, when faster breathing can deliver more ozone deeper into the lungs. (eurekalert.org) A 2023 primer in *Pediatric Pulmonology* described ground-level ozone as a “potent respiratory toxicant” for children and said exposure is linked to respiratory harms in both healthy children and those with underlying disease. The American Lung Association separately says ground-level ozone can damage lung tissue and trigger breathing problems. Those sources do not evaluate this ATS study, but they are consistent with the biological explanation Scales gave for why ozone may blunt exercise-related gains. (eurekalert.org) ### What did the study say about WHO-style activity targets? ATS said the findings suggest the benefits of exercising at levels recommended by the World Health Organization may be limited by environmental conditions. Healio reported that Scales said there were no associations between lung growth and moderate physical activity or with time-based WHO guidelines for physical activity in this analysis. That means the issue in this dataset was not simply whether children were active, but whether they were doing enough vigorous activity and what air they were breathing while doing it. (pmc.ncbi.nlm.nih.gov) Scales told Healio the team was studying what he called a “planetary health paradox” — the possibility that a behavior promoted as healthy may also raise exposure to harmful pollutants. That interpretation was his description of the research question, not a policy conclusion from the study alone. (eurekalert.org) ### How should readers treat these findings right now? ATS identified the work as a conference presentation, not a full peer-reviewed journal paper. Conference abstracts can change before journal publication, and the public materials available so far are summary-level accounts rather than a full methods paper. The abstract was presented on May 20 in Orlando during ATS 2026, and ATS says conference content from this year’s meeting will remain available on its platform through Dec. 31, 2026. (healio.com) For now, the named next steps are limited: the study has been presented, the abstract has been listed in the ATS meeting record, and CHILL continues as an active research cohort run through Queen Mary University of London. (healio.com) (eurekalert.org)