Abstract Rationale Physical activity is essential for child health, yet the environments where children play are increasingly affected by anthropogenic air pollution. Ozone (O3), a potent oxidant gas that causes epithelial damage in the airways, may negate the respiratory benefits of physical activity by increasing inhaled dose during exertion. The relationship between physical activity intensity and lung growth in children, and how this is modified by long-term air pollution exposure, remains unclear. This study examined whether vigorous physical activity promotes lung growth and whether these effects are modified by chronic exposure to O3 and other pollutants. Methods We analysed longitudinal data from 3,414 children aged 6–9 years enrolled in the Children’s Health in London and Luton (CHILL) study, a prospective cohort followed annually for up to four years. Physical activity was objectively measured each year using Actigraph accelerometers to quantify vigorous (VPA) and moderate-to-vigorous physical activity (MVPA). Post-bronchodilator forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were assessed annually via spirometry. Annual residential exposures to O3, PM2.5, PM10, and NO2 were estimated using high-resolution hybrid atmospheric models (20 m resolution). Mixed-effects linear regression models with random intercepts for child and school were used to assess associations, adjusting for demographic, socioeconomic, environmental, and seasonal covariates. Results Vigorous physical activity was significantly associated with greater annual growth in both FEV1 (β = 0.0011 L·yr−1; 95% CI 0.0001–0.0020; p = 0.028) and FVC (β = 0.0012 L·yr−1; 95% CI 0.0002–0.0023; p = 0.017), equivalent to approximately 10 mL increased lung volume per 10 minutes of daily VPA. No associations were observed for MVPA or adherence to WHO time-based guidelines. O3 exposure attenuated these beneficial associations at all intensities, while PM2.5 and PM10 demonstrated neutral or slightly positive modifying effects. Results were robust to adjustment for confounders and across sensitivity analyses. Conclusions Vigorous physical activity supports healthy lung growth in children, but this benefit is diminished in environments with high ozone levels. Moderate activity and meeting WHO guidelines alone did not enhance lung growth. These findings highlight the need to integrate air-quality considerations into global physical-activity recommendations. Without addressing environmental determinants such as ozone pollution, children in more polluted areas may be unable to achieve the same developmental health benefits from physical activity as their peers in cleaner environments. This abstract is funded by: NIHR UK
Scales et al. (Fri,) studied this question.