Associations between Size-Specific Particulate Matter and Lung Function: Results from the China Pulmonary Health Study.

Emerging evidence suggests that the respiratory health effects of particulate matter (PM) may vary by aerodynamic diameter. However, comprehensive investigations comparing the effects of size-specific PM on lung function indicators remain limited. We analyzed lung function data from the China Pulmonary Health (CPH) Study to assess the associations between long-term exposure to PM1, PM1-2.5, PM2.5, PM2.5-10, and PM10 and indicators of large and small airway function using multivariable linear models. This study included 50,991 adults aged 20 years and above. For large airway function, each interquartile range (IQR) increase in PM1, PM1-2.5, PM2.5, and PM10 was significantly associated with a decrease in FEV1, FVC, and FEV1/FVC. The associations between FEV1 and FVC strengthened as the particle size decreased. PM1 showed the strongest association, with the lowest FEV1 (-36.84 mL, 95% confidence interval (CI): -45.91, -27.76 mL) and FVC (-34.63 mL, 95% CI: -45.48, -23.79 mL) values. For small airway function, all size-specific particles were significantly associated with decreases in FEF75 and FEF25-75. Specifically, each IQR increase in PM2.5-10 exposure was associated with the largest reduction in the airway function indicators. Furthermore, stratified analyses showed stronger adverse associations in vulnerable subpopulations, including females, older adults, former smokers, biomass nonusers, and participants with chronic obstructive pulmonary disease (COPD). Size-specific PM exposure has differential health effects on both large and small airway lung function indicators. Therefore, it is essential to account for particle size in health risk assessments and the regulation of PM.