Ambient air pollution, lung function and COPD: Cross-sectional analysis from the WHO Study of AGEing and adult health wave 1

Background Long-term exposure to ambient air pollution leads to respiratory morbidity and mortality; however, the evidence of the effect on lung function and chronic obstructive pulmonary disease (COPD) in older adult populations is inconsistent. Objective To address this knowledge gap, we investigated the associations between particulate matter (PM), nitrogen dioxide (NO 2) exposure and lung function, as well as COPD prevalence, in older Chinese adults. Methods We used data from the WHO Study on global AGEing and adult health (SAGE) China Wave 1, which includes 111 693 participants from 64 townships in China. A cross-sectional analysis explored the association between satellite-based air pollution exposure estimates (PM with an aerodynamic diameter of ≤10 μm [PM 10], ≤2.5 μm [PM 2.5] and NO 2) and forced expiratory volume in one second (FEV 1), forced vital capacity (FVC), the FEV 1/FVC ratio and COPD (defined as post-bronchodilator FEV 1/FVC <70%). Data on lung function changes were further stratified by COPD status. Results Higher exposure to each pollutant was associated with lower lung function. An IQR (26.1 μg/m 3) increase in PM 2.5 was associated with lower FEV 1 (-71.88 mL, 95% CI-92.13 to-51.64) and FEV 1/FVC (-2.81 mL, 95% CI-3.37 to-2.25). For NO 2, an IQR increment of 26.8 μg/m 3 was associated with decreases in FEV 1 (-60.12 mL, 95% CI-84.00 to-36.23) and FVC (-32.33 mL, 95% CI-56.35 to-8.32). A 31.2 μg/m 3 IQR increase in PM 10 was linked to reduced FEV 1 (-8.86 mL, 95% CI-5.40 to 23.11) and FEV 1/FVC (-1.85 mL, 95% CI-2.24 to-1.46). These associations were stronger for participants with COPD. Also, COPD prevalence was linked to higher levels of PM 2.5 (POR 1.35, 95% CI 1.26 to 1.43), PM 10 (POR 1.24, 95% CI 1.18 to 1.29) and NO 2 (POR 1.04, 95% CI 0.98 to 1.11). Conclusion Ambient air pollution was associated with lower lung function, especially in individuals with COPD, and increased COPD prevalence in older Chinese adults.