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

Per 10-µg/m³ increase in PM2.5 was associated with lower CRF levels in children and adolescents.

• Each 10-µg/m³ increase in PM2.5 was associated with -0.12 (95% CI, -0.13 to -0.10) mL/kg per min lower CRF levels.
• CRF was estimated using a 20-m shuttle run test.
• Long-term exposure was defined as 3-year average (2013–2015) concentrations before the study.
• The sample consisted of 99,995 children and adolescents in China obtained via multistage random cluster sampling.

Per 10-µg/m³ increase in PM10 was associated with lower CRF levels in children and adolescents.

• Each 10-µg/m³ increase in PM10 was associated with -0.09 (95% CI, -0.10 to -0.08) mL/kg per min lower CRF levels.
• Daily exposure to PM10 surrounding schools was extracted from the China High Air Pollutants datasets.
• The association was statistically significant based on the confidence intervals not crossing zero.

The association between particulate matter and CRF was nonlinear.

• Exposure-response curves suggested a nonlinear association of both PM2.5 and PM10 with CRF.
• All P nonlinear <0.001 for both PM2.5 and PM10.
• CRF was estimated by a 20-m shuttle run test as the outcome measure.

Waist-to-height ratio (adiposity) mediated a significant portion of the association between PM2.5 and CRF.

• Waist/height ratio mediated 15.97% (95% CI, 13.99%–18.27%) of the association between PM2.5 and CRF.
• The mediation was statistically significant (P<0.001).
• Adiposity was assessed using waist/height ratio as a surrogate measure.

Waist-to-height ratio (adiposity) mediated a significant portion of the association between PM10 and CRF.

• Waist/height ratio mediated 16.15% (95% CI, 13.92%–18.75%) of the association between PM10 and CRF.
• The mediation was statistically significant (P<0.001).
• These findings suggest adiposity only partially explains the particulate matter–CRF association.

A nationwide sample of children and adolescents in China was used, with particulate matter exposure data derived from the China High Air Pollutants datasets.

• A multistage random cluster sampling method was used to obtain 99,995 children and adolescents.
• Daily exposure to PM2.5 and PM10 surrounding schools was extracted from the China High Air Pollutants datasets.
• Three-year average concentrations (2013–2015) were used as surrogates of long-term exposures.
• PM2.5 refers to particulate matter with aerodynamic diameter ≤2.5 µm and PM10 refers to aerodynamic diameter <10 µm.