Impact of improved air quality on lung function and blood pressure of middle-aged and older population in China.

Long-term exposure to fine particulate matters (PM) has been associated with respiratory and cardiovascular diseases and the burden are potentially higher in China experiencing heavy air pollution. In this study, we established the exposure-response association between long-term exposures to PM and lung function and blood pressure in Chinese middle-aged and older adults using linear mixed-effects and generalized additive mixed models based on 3 waves longitudinal health outcomes data by enrolling 19,988 participants from 121 cities across the mainland of China. We also assessed the effect of Clean Air Policy (CAP) based on a quasi-experimental difference-in-differences (DID) design. A 10 µg/m increase in PM concentration was associated with a 7.18 (95 % confidence interval [CI]: -8.35, -6.02) L/min decrease in PEF (peak expiratory flow) and a 0.72 (95 % [CI]: 0.53, 0.90) and a 0.30 (95 % [CI]: 0.18, 0.42) mmHg increase in systolic and diastolic blood pressure, respectively. The associations were more pronounced in males and rural areas for PEF, but similar across subgroups for blood pressure. DID results suggested that the effect of CAP on health outcomes were sensitive to magnitudes of reduction in PM. A 5 µg/m reduction in PM or more generally led to 18.70 (95 % [CI]: 0.79, 36.61) higher PEF and -2.05 (95 % [CI]: -3.87, -0.23) lower diastolic blood pressure, respectively, compared to no reduction or increase in exposure. However, the effects were significant only in rural areas. Our analysis support CAP aiming to benefit public health and provides insights to inform future control policy for efficiently decreasing air pollution exposure burden.