Abstract
Climate change and air pollution pose multiple health threats to humans through complex and interacting pathways, whereas urban vegetation can improve air quality by influencing pollutant deposition and dispersion. This study estimated the amount of PM2.5 removal by the urban forest in the city of Shanghai by using remote sensing data of vegetation and a model approach. We also identified its potential contribution of urban forest presence in relation to human population and particulate matter concentration. Results show that the urban forest in Shanghai reached 46,161 ha in 2017, and could capture 874 t of PM2.5 with an average of 18.94 kg/ha. There are significant spatial heterogeneities in the role of different forest communities and administrative districts in removing PM2.5. Although PM2.5 removal was relatively harmonized with the human population distribution in terms of space, approximately 57.41% of the urban forest presented low coupling between removal capacity and PM2.5 concentration. Therefore, we propose to plant more trees with high removal capacity of PM2.5 in the western areas of Shanghai, and increase vertical planting in bridge pillars and building walls to compensate the insufficient amount of urban forest in the center area.
Highlights
The world’s urban population has rapidly increased from 751 million in 1950 to4.2 billion in 2018 [1]
Our estimated results show that the daily amount of PM2.5 removal ranged from 0 to 11.57 t, and urban forests performed a larger amount of pollutant removal in summer and autumn (Figure 4)
The removal capacity of urban forests decreased to 1.95 t/day in winter because of the fall of leaves
Summary
The world’s urban population has rapidly increased from 751 million in 1950 to4.2 billion in 2018 [1]. Climate change and air pollution have posed multiple health threats to humans through complex and interacting pathways [2], and urban air pollution has become a global environmental issue [3]. Particulate matter (PM) refers to the solid and liquid particles in the atmosphere; it is usually a key air pollutant that increases the occurrence probability of air pollution and haze events [4]. Air pollution adversely causes an increase in respiratory and cardiovascular diseases [5,6], excess mortality, and a decrease in life expectancy [7,8]. It is projected that climate change will continue to affect air quality, including ozone and fine particles [2]. Urban vegetation has been highlighted to offer a mitigation potential against atmospheric particulate pollution [9].
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