Quantifying the Potential Contribution of Urban Forest to PM2.5 Removal in the City of Shanghai, China

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.

Breathing Fresh Air in the City: Implementing Avenue Trees as a Sustainable Solution to Reduce Particulate Pollution in Urban Agglomerations

“…In contrast, Brooklyn Industrial Precinct in Perth, Australia’s western suburbs had a yearly pollutant removal of 294 t [ 133 ]. In Shanghai, China, the annual PM 2.5 reduction can reach 442.4 t per year [ 151 ]. There may be a connection between trees’ ability to purify the air and the following factors: an increase in vegetation cover lowers the sources of PM 2.5 ; various tree organs can absorb PM; a decrease in wind speed may cause PM fallout; and a change in wind direction may stop PM 2.5 from being transported into specific areas [ 152 ].…”

Impact of Urban Forest and Park on Air Quality and the Microclimate in Jinan, Northern China

“…Previous studies on the impact of urban vegetation on PM 2.5 and O 3 have mainly focused on the removal capacity of vegetation, with few studies investigating the concentration differences inside and outside of urban forests or parks, which is not conducive to guiding residents to carry out leisure activities [22,27]. In addition, most studies in China have focused on megacities such as Beijing, Shanghai, and Shenzhen [27,30,31], while cities in the heavily polluted North China Plain region have not received sufficient attention. As such, we cannot yet quantify the impact of trees in urban forest and urban park areas on air quality and the microclimate for these cities.…”