Fine particulate matter in Chinese cities : patterns, regional transport, and mitigation

Abstract

China is facing severe PM2.5 pollution, particularly in Beijing and its surrounding municipalities. PM2.5 pollution not only undermines the reputation of China as a liveable and economically prosperous nation but also poses critical challenges for Chinese citizens and governments in terms of sustainable development and public health. This dissertation aims to provide knowledge on the patterns of variation and regional transport of PM2.5 pollution, and propose a zoning framework that can aid in the formulation of pollution mitigation policies and measures in China. This dissertation asks three individual yet connected research questions: 1) How do the PM2.5 concentrations in Beijing vary across time?; 2) Is the regional transport of PM2.5 significant and must Beijing blame the other cities for emitting pollution?; and 3) What are the exact boundaries of the area responsible for the PM2.5 pollution in Beijing, and can we use a decision support tool to determine the area within the necessary policies must be enforced? Chapter Three addresses the first research question to understand the temporal variation patterns of the PM2.5 pollution in Beijing. This study visualizes the full-year PM2.5 data in Beijing in 2014 on a daily basis by applying time-series cluster analysis and an innovative calendar visualization technique. The results on the temporal variation of PM2.5 concentrations reveal three diurnal patterns and no weekly patterns. Seasonal patterns have also been observed, but they do not follow a strict temporal division. Chapter Four addresses the second research question to explore the regional transport patterns of PM2.5 in the Beijing–Tianjin–Hebei area. This study initially assumes that regional transport is significant and then examines what the PM2.5 concentrations would be under such assumption. As expected, the time-delay estimation analysis using the PM2.5 data reveals an interesting and significant time-lagged inter-city correlation of PM2.5 concentrations, which can be explained by regional transport of PM2.5. Further visualization analysis reveals that the PM2.5 pollution in Beijing between April and June may be influenced by southern cities (e.g., Cangzhou), while the PM2.5 pollution in southern cities in other months may be attributed to Beijing. Chapter Five addresses the third research question to determine the exact boundaries of the area responsible for the PM2.5 pollution in Beijing and the size of area within the necessary measures and regulations must be enforced. By proposing a zoning framework that delineates the PM2.5 boundaries for air pollution control in China using a time-series cluster analysis technique, this study provides a decision support tool for developing region-specific measures, such as the natural gas heating program in north China for mitigating air pollution. The answers to these questions improve the current understanding of PM2.5 pollution in China as well as offer different perspectives toward the temporal variation of PM2.5 pollution through calendar visualization. The findings on the regional transport of PM2.5 and the zoning framework offer significant policy, social, and research implications, and will be of great value to policy makers, practitioners, and researchers in the field of environmental management and urban planning.