Impact Of The Implementation Of The “Air Pollution Prevention And Control Action Plan” On Hong Kong And Evaluation Of Health Benefits

Inhalable particulate matter(PM₁₀)pollution is a major air pollution problem in Hong Kong Special Administrative Region（hereinafter referred to as"Hong Kong Region"）,which seriously harms human health and ecological environment.Previous studies have shown that air quality in Hong Kong has been greatly affected by air quality in the mainland.The“Air Pollution Prevention and Control Action Plan”（hereinafter referred to as the"Plan"）issued by the Chinese government in 2013 has significantly improved the air quality in many parts of China,and its main target PM₁₀ decreased by more than 30%in 2017.Considering the regional transport mechanism of PM₁₀ and the sources of air pollution in Hong Kong,it is an important direction to study the indirect impact of regional transport of PM₁₀ on Hong Kong after the implementation of the"Plan"in the mainland,compared with the study of PM₁₀ pollution in a region alone.Taking the atmospheric PM₁₀ and its chemical components in Hong Kong before and after the implementation of the"Plan"as the starting point,this thesis studies the indirect impact of mainland air quality on Hong Kong and qualifies the benefits of indirect impacts,which will help to deepen the regional transmission of air pollution and the understanding of the implementation of benefits of the"Plan",and provides scientific basis for the evaluation and formulation of air pollution prevention and control policies.The aim of this study is to study the concentrations of PM₁₀ and the chemical composition of PM₁₀ samples taken weekly from eight sites in Tsuen Wan,Kwai Chung,Kwun Tong,Central and Western Districts,Mongkok,Yuen Long,Sham Shui Po and Tung Chung in Hong Kong from January 1,2009 to December 31,2017.In this thesis,the backward trajectory model（HYSPLIT）and de-trended cross-correlation analysis（DCCA）were organically integrated to study the complex relationship of PM₁₀ between in the mainland and Hong Kong from two aspects of regional transport causality and correlation.Based on this analysis,using the proportional risk model and human capital method to quantify the health benefits of air quality improvement in the Mainland for Hong Kong after the implementation of the"Plan".The main results of the study are as follows:Firstly,by comparing and analyzing the change trend of PM₁₀ and its chemical components in Hong Kong from 2009 to 2013 and 2013 to 2017,it is found that the concentration of PM₁₀ and the average mass of chemical components of PM₁₀（sulfate,nitrate,ammonium,organic carbon,mineral dust,heavy metal elements and elemental carbon）of in Hong Kong decreased significantly from 2013 to 2017,and the air quality improved significantly.From 2013 to 2017,compared with 2009 to 2013,the average PM₁₀ concentration in Hong Kong,roadside stations,general stations and port stations decreased by 15%,16.5%,13.6%and 17%,respectively.The average value of PM₁₀concentration at all stations in Hong Kong decreased the most in the autumn and winter,and less in summer.In connection with the implementation effect of the"Plan"in the mainland,it is considered that the decrease in the concentration of PM₁₀ and its chemical components in Hong Kong may be due to the reduction of PM₁₀ transport after the improvement of air quality in the Mainland.Secondly,using HYSPLIT,trajectory clustering and CWT methods to trace the source of atmospheric PM₁₀ in Hong Kong from 2013 to 2017.The results show that PM₁₀transport from the mainland is the main source of PM₁₀ in Hong Kong,and air pollution transport from the mainland is the main cause of PM₁₀ pollution in Hong Kong.The variation of air pollution in Hong Kong in spring,autumn and winter is mainly controlled by air flow from the mainland,while in summer it is influenced by air flow from the South China Sea.The weighted concentration of PM₁₀ from the mainland in Hong Kong was higher in winter and lower in summer.Further,through DCCA method and Kriging interpolation,the relationship between mainland PM₁₀ and Hong Kong PM₁₀ is analyzed.The correlation is the weakest in summer and stronger in the other three seasons.The correlation of this impact model has the characteristics of long-term persistence.Specifically,the change of the correlation between PM₁₀ pollution in the mainland and Hong Kong with time does not follow the classical Markov process,that is,it does not decay exponentially with time,but slowly weaken over time.This indicates that PM₁₀from the Mainland will continue to accumulate after reaching Hong Kong through regional transport,and there is a certain long-term persistence regardless of the length of time scale,which proves that the implementation of the"Plan"plays an important indirect role in the atmospheric environment of Hong Kong.Combined with causality and correlation,the transport mode and response mode of PM₁₀ in Hong Kong and the mainland were analyzed,and the results showed that the reduction of PM₁₀ concentration in Hong Kong was mainly due to the influence of the"Plan".Third,based on the proportional hazards model and the human capital method,the indirect benefits brought by the"Plan"to Hong Kong were quantified.Compared with2013,the estimated health benefits of PM₁₀ concentration reduction in 2017 were about7.39 billion yuan,and about 1.5 billion yuan of health benefits were generated every year from 2013 to 2017.Indirectly,the"Plan"prevented 1,629 premature deaths,3,759 fewer cases of chronic bronchitis and asthma due to PM₁₀ pollution,and 1,550 hospital admissions for cardiovascular and respiratory diseases due to PM₁₀ pollution.Finally,this thesis effectively integrates the change of PM₁₀ in Hong Kong with the regional transport of air pollution in the mainland,and extracts key change information from the changes of PM₁₀and its chemical components in Hong Kong before and after the implementation of the"Plan".On this basis,based on HYSPLIT to explore the potential sources of PM₁₀ in Hong Kong,and using DCCA analysis method to clarify the long range correlation of PM₁₀ in the process of atmospheric transport between the mainland and Hong Kong The results shows that the implementation of the"Plan"has a significant indrect impact on the air environment of Hong Kong,mainly because the"Plan"reduces the air pollution in east,south and part of central China,and then improves the air quality of Hong Kong through regional transport.The last step is a quantitative analysis of the impact of the reduction of PM₁₀ concentration on human health.The implementation of the"Plan"has greatly reduced the concentration of PM₁₀ in Hong Kong,bringing 7.39 billion yuan of health benefits to Hong Kong.In order to avoid PM₁₀pollution aggravating with economic growth,regional joint prevention and control with Guangdong should be strengthened.Starting from the change of PM₁₀ concentration in Hong Kong,this thesis has deepened the understanding of the influence strength and actual effect of the"Plan".Under the major background of the current ecological civilization construction in China,based on the results,it has very important practical significance for the formulation and appropriate adjustment of air pollution control strategies in China.