Correlation between NDVI and PM2.5 Concentrations in a Small-Scale Urban Area

Abstract

Abstract Urban green space plays a significant role in protecting the environment and purifying the air. In a city, green infrastructures are interconnected in a large system, which can play a positive role in the ecological protection of the city; meanwhile, in the main urban areas of large cities with complex land use types, the distribution of green infrastructure is disorderly, and how to effectively determine the actual effect of green space on PM2.5 at an urban small scale is still a challenge. Smog in southern Chinese cities primarily occurs in spring and winter, so we chose Nanjing, one of the largest megacities in southern China, as a case study, and chose spring and winter as the research time series. We took 11 air monitoring points as the core and delimited a radius of 500 meters as the research area, tracked and monitored the changes in PM2.5 values at 11 stations for 2 months, and then conducted a correlation analysis between this change and the NDVI (Normalized Difference Vegetation Index) values of the 11 regions. The analysis shows that in the main urban area, green space can have an obvious influence on the ambient air state within 500 m. In addition, when the NDVI value was high, the PM2.5 concentration in the corresponding area was low, and the correlation reached 0.89 on average (1 is a perfect correlation); the mean regression equation was y = 56.3–0.088x. In addition, the correlation was stronger when the PM2.5 concentration was higher, indicating that green space in the main urban area can play an obvious ecological efficiency role in the extremely polluted atmospheric environment. These research results reveal for the first time the impact of green space on air particles in small-scale urban space, which is conducive to better optimization of green space layout to better give full play to the ecological function of green space in response to public health events.