Quantifying the effect of air particle pollution mitigation by dry deposition in Chinese residential areas

Air pollution has increased in the last decade all around the world, especially in developing countries, such as in China. A series of control polices, laws, and regulations were enacted by the Chinese government. However, particulate matters are still the main type air pollution in northern China. Air pollution, such as PM2.5 and PM10, impacts human health and well-being, ecosystem health, and the climate. Urban green infrastructure is pointed out as a nature-based method to improve air quality. Air pollution can be reduced by urban green infrastructure in many ways. For instance, urban tree can act as vegetation barriers to prevent the penetration of pollutants into certain areas. They can also removal pollutants from the atmosphere by dry deposition process on the tree canopy. However, most dry deposition studies focus on a city scale. Therefore, this study aims to explore optimization of urban green plans for air quality improvement in the mid-scale residential area. Based on a literature review of the development of dry deposition studies and the application in urban planning and design, the commonly used models of green spaces effect have limited consideration of the impact of wind speed and tree species and lack focus on mid-scale areas. So, this study develops a green planning model to estimate the effect of urban vegetations on particulate matter pollution mitigation by dry deposition. This model contains two parts, which are a CFD model (ENVI-met) and a SD model (Vensim PLE). The model setup and boundary conditions are described in three steps, which are 1) identification of land types by local microclimate zones; 2) collection of meteorological and air quality data; 3) calculation of air pollution removal. This model is validated by a comparison that is made between monitored particle pollutant concentration data and simulated concentration rustles of the model in the study area in Taiyuan, China. Then, this green planning model is applied in a mid-scale residential area to explore optimum green plans of this area. The results are analyzed and discussed to propose an optimum green plan, which is to have 14% - 25% green cover with evergreen leaf trees that are planted in the locations with higher wind speeds. Finally, this thesis summarizes the contributions of the urban planning model and the findings of the simulation results, as well as the direction of future study