Do We Need More Urban Green Space to Alleviate PM_2.5 Pollution? A Case Study in Wuhan, China

Urban green space can help to reduce PM_2.5 concentration by absorption and deposition processes. However, few studies have focused on the historical influence of green space on PM_2.5 at a fine grid scale. Taking the central city of Wuhan as an example, this study has analyzed the spatiotemporal trend and the relationship between green space and PM_2.5 in the last two decades. The results have shown that: (1) PM_2.5 concentration reached a maximum value (139 µg/m³ ) in 2010 and decreased thereafter. Moran’s I index values of PM_2.5 were in a downward trend, which indicates a sparser distribution; (2) from 2000 to 2019, the total area of green space decreased by 25.83%. The reduction in larger patches, increment in land cover diversity, and less connectivity led to fragmented spatial patterns of green space; and (3) the regression results showed that large patches of green space significantly correlated with PM_2.5 concentration. The land use/cover diversity negatively correlated with the PM_2.5 concentration in the ordinary linear regression. In conclusion, preserving large native natural habitats can be a supplemental measure to enlarge the air purification function of the green space. For cities in the process of PM_2.5 reduction, enhancing the landscape patterns of green space provides a win-win solution to handle air pollution and raise human well-being.