Research On Spatio-temporal Characteristics Of Urban Air Pollution In China And Its Socio-economic Influencing Factors

Four decades had passed since the reform and opening up policy started.China has witnessed rapid economic growth and urbanization.As a consequence of rapid large-scale urbanization,China suffers from the serious issues of environmental pollution.Notably air pollution has frequently occurred in recent years,which not only causes economic losses,but also poses a great threat to people's health.Hence,air pollution prevention and control are urgently needed in China.Based on the existing literature,the main aims of this thesis are to analyze spatio-temporal characteristics of urban air pollution and discover its socio-economic influencing factors.Specifically,it used a dataset of air quality index of 329 cities and employed multi-disciplinary methods to analyze the spatiotemporal characteristics of urban air pollution.In addition,it had a discussion of the influencing factors of air pollution based on a dataset of 289 cities in 2016.From the above analysis,a series of policy handles are proposed to prevent and control air pollution.The main structure of the thesis is as follows.Firstly,before going to the discussions of the spatio-temporal characteristics of urban air pollution and its socio-economic influencing factors,one task is to determine the research sample.Through extensive and in-depth literature review,it is found that most of the existing studies used a single indicator pollutant to reflect air pollution,or constructed a comprehensive indicator.However,a comprehensive,authoritative and objective air quality indicator is needed.Therefore,the air pollution index and air quality index(AQI)issued by the Ministry of Ecology and Environment of China filled the gap.Compared the air pollution index,the air quality index is more accurate since it includes more individual pollutant indicators.Hence,the air quality index is a better indicator to describe air pollution in China.By means of thorough literature review,few studies on this air quality index were found.Hence,this thesis used a dataset of air quality index during the period of 2015-2017 to analyze the spatio-temporal characteristics of air pollution and its socio-economic influencing factors.Secondly,the global spatial autocorrelation method,empirical orthogonal function and spatial descriptive statistical analysis were applied to analyze the spatio-temporal variation of urban air pollution.The findings are the following.During the sample period,it could be found that air quality increased year by year and the polluted area became smaller.From the seasonly time scale,it presented a regular pattern with high AQI values in winter and low AQI values in summer.Besides,the polluted areas widened in winter and narrowed in summer.From the monthly time scale,AQI values showed a U-shaped curve with the lowest values from June to August.What's more,AQI values had stronger spatial clusters in January,June and December.From the perspective of the daily time scale,AQI values fluctuated wildly in winter and slightly in summer.In addition,the excellence rate of air quality in China presented a distinct spatial distribution with low values in north and high values in south.Thirdly,from the perspectives of spatial dependence and spatial heterogeneity,it continued to apply the spatial lag model and geographically weighted regression model to analyze the socio-economic influencing factors of AQI.It took into account seven factors,namely,population,affluence,technological levels,industrial structure,urban built-up area,urban transportation and PM2.5.The findings are the following.Economic growth,the expansion of built-up area,and the increase of PM2.5 concentration increased air pollution while environmental awareness and the increase in technological levels lower urban air pollution.Besides,it could be found that air pollution spread to neighboring cities due to atmospheric circulation from the results of the spatial lag model,indicating a significant and positive spatial spillover effects of air pollution in geography.In addition,there are huge differences in influencing factors from city to city,implying remarkable spatial heterogeneity.From the impact of the economic growth factor on air pollution,the coefficients of the cities in the Hu Line westward were bigger than those in the Hu Line eastward while the coefficients of the cities in the north of the Yangtze River were bigger than those in the south.Finally,from the above discussions,a series of policies to prevent and control urban air pollution in China are proposed.They are summarized as follows.(1)The next stage of China's air pollution control priority is to prevent seasonal mutations in air pollution.(2)A new way of win-win and shared pollution control measurement for the whole people should be highly encouraged.(3)Joint prevention and control of air pollution and enhancement of regional coordinated green development are also urgently needed.