Effects of green spaces on alleviating mortality attributable to PM_2.5 in China

Increasing research suggested that green spaces are associated with many health benefits, but evidence for the quantitative relationship between green spaces and mortality attributable to particulate matter with an aerodynamic diameter of 2.5 μm or less (PM_2.5) is limited. We collected disease-specific mortality and PM_2.5 data for a period of 4 years (2015-2018) along with green space data for an 8-year duration (2010-2017) in 31 provincial-level administrative regions of China. First, this study used the Integrated Exposure-Response model to estimate the mortality of four diseases attributable to PM_2.5, including chronic obstructive pulmonary diseases (COPD), lung cancer (LC), ischemic heart disease (IHD), and cerebrovascular disease (CBVD). Then we performed linear regression and mixed-effects model to investigate the counteracting effect of green spaces on death caused by PM_2.5 exposure. The differences in impacts among the Eastern, Central, and Western regions were explored using stratified analysis. The most significant results from linear regression analysis indicated that per 100 km² of green spaces increase, there was a decreased total mortality (10^-5) (COPD, LC, IHD, and CBVD) attributable to PM_2.5 by - 4.012 [95% confidence interval (CI): - 5.535, - 2.488], while the reduction by mixed-linear regression analysis was - 2.702/10⁵ (95% CI =  - 3.645, - 1.759). Of all hysteresis analyses, the effect estimates (β) at lag3 and lag4 were the largest. The effect of green spaces was more advantageous when targeting CBVD and the Eastern region. We found a negative correlation between green space exposure and mortality attributable to PM_2.5, which can provide further support for city planners, government personnel, and others to build a healthier city and achieve national health goals.