Negative and Nonlinear Association Between Particulate Matter and Cardiorespiratory Fitness Among Children and Adolescents: The Mediating Effect of Adiposity

Background Cardiorespiratory fitness (CRF) has been investigated as a broad, holistic health indicator for children and adolescents. The adverse effects of particulate matter on lung function and cardiovascular health have been widely reported, whereas the association between particulate matter and CRF and its potential pathways remains unclear. The study aims to estimate the association between particulate matter and CRF in children and adolescents and the mediating effect of adiposity on this association. Methods A multistage random cluster sampling method was used to obtain a nationwide sample of 99 995 children and adolescents in China. Daily exposure to particulate matter with aerodynamic diameter ≤2.5 and <10 μm surrounding schools was extracted from the China High Air Pollutants data sets. As surrogates of long‐term exposures, we used 3‐year average (2013–2015) concentrations before the study for analyses. CRF was estimated by a 20‐m shuttle run test. Results Per 10‐μg/m 3 increase in particulate matter with aerodynamic diameter ≤2.5 and <10 μm was associated with −0.12 (95% CI, −0.13 to −0.10) and −0.09 (95% CI, −0.10 to −0.08) mL/kg per min lower CRF levels. Exposure‐response curves suggested a nonlinear association of particulate matter with CRF (all P nonlinear <0.001). Waist/height ratio mediated 15.97% (95% CI, 13.99%–18.27%) and 16.15% (95% CI, 13.92%–18.75%) of the association between particulate matter with aerodynamic diameter ≤2.5 and <10 μm, respectively, and CRF among children and adolescents (all P <0.001). Conclusions There is a negative and nonlinear association between long‐term exposure to particulate matter and CRF among children and adolescents, and this association may be partially explained by adiposity. Cohort studies are needed to further validate the findings.