The Influence Mechanism Of Social And Economic Factors On Composite Air Pollution

A good ecological environment is an important support for high-quality development,and the atmospheric environment is an important part of the ecological environment,therefore,a good battle against air pollution is an effective way to promote the high-quality development of China’s economy.The report of the 20th CPC National Congress points out the new idea of continuously promoting the prevention and control of air pollution:strengthening the management of urban air quality standards,strengthening the synergistic control of pollutants,vigorously promoting the synergistic emission reduction of volatile organic compounds（VOCs）and nitrogen oxides（NOx）,and at the same time,continuing to promote the synergistic control of PM and O₃,and effectively curbing the trend of growth in the concentration of O₃.China’s atmospheric pollution is undergoing a process of unravelling from local to wide-area transformation,and atmospheric pollution embodies composite characteristics.Therefore,the study of the current situation of China’s composite atmospheric pollution and its influence mechanism,and the targeted policy recommendations for the synergistic emission reduction of pollutants is an important topic for the realization of ecological civilisation.This paper will focus on four aspects of research:first,the construction and measurement of China’s Composite Air Pollution Index,second,the characterisation of the spatial and temporal evolution of China’s Composite Air Pollution Index,third,the study of the mechanism of influence of socio-economic factors on the evolution of the level of China’s Composite Air Pollution Index,and fourth,the study of the mechanism of influence of socio-economic factors on the evolution of the structure of China’s Composite Air Pollution Index.Firstly,this paper measures China’s composite atmospheric pollution by constructing a multi-pollutant weighted air quality comprehensive evaluation model,the Composite Air Pollution Index（CAPI）,by combining the information of the main atmospheric pollutants(CO,NO₂,O₃,PM₁₀,PM_2.5and SO₂).The index measures China’s composite air pollution from both horizontal and structural aspects,reflecting the primary and secondary relationships of each pollutant in air pollution.On this basis,the Composite Air Pollution Index CAPI was calculated for 337 prefecture-level cities in China from 2015 to 2020,incorporating both CAPI level and CAPI structure.Then,the spatio-temporal evolution characteristics of the Composite Air Pollution Index CAPI of 337 prefecture-level cities in China from 2015 to 2020 were investigated,using Bayesian spatio-temporal hierarchical segmented regression model to study the spatio-temporal evolution characteristics of the CAPI levels,and later describing the spatio-temporal evolution characteristics of the CAPI structure.The study found that（1）CAPI levels possessed distinctive spatial and temporal evolution characteristics.In terms of spatial distribution,the CAPI level is higher in Beijing-Tianjin-Hebei-Shanxi-Henan-Shandong and Northwest China,lower in Southeast,Southwest and Northeast China.In terms of temporal change,the overall change shows that the CAPI of China’s urban atmospheric composite pollution index declined year by year during the study period,and the local changes can be divided into two phases:in the first phase,the trend of local changes in the CAPI in the northwestern,southwestern and southeastern regions is faster,while the trend of local changes in the CAPI in the Beijing-Tianjin-Hebei-Shanxi-Henan-Shandong and northeastern regions is slower;and in the second phase,the trend of local increases in the CAPI in the northeastern region is faster,and the trend of local increases in the CAPI in the northwestern and southwestern regions is slower.（2）The CAPI structure also has significant spatial and temporal evolution characteristics.In terms of spatial distribution,the proportion of CO in the CAPI is higher in the south than in the north;the proportion of NO₂in the CAPI is higher in the east and centre than in the west;the proportion of O₃in the CAPI is larger in the north,west and south of China than in the centre and east;the proportion of PM_2.5in the CAPI is larger in the centre and east of China than in the north,west and south;except for part of the western region,most of the regions of China have an important role in PM₁₀in atmospheric pollution;the proportion of SO₂in CAPI is at a low level in the whole country.In terms of temporal change,the share of CO in the CAPI was relatively stable,the share of NO₂in the CAPI increased and then stabilised,the importance of O₃in the CAPI weakened and then increased year by year in 2018,PM₁₀accounted for the largest share in the CAPI,and the importance of PM_2.5and SO₂in the CAPI decreased gradually.Then,a Bayesian spatial model（INLA-SPDE）was used to study the influence mechanism of socio-economic factors on the CAPI level of urban air pollution.The results of the model show that the effects of economic development and environmental regulation on CAPI levels show an inverted"U"trend,and the increase of population density,industrial scale,energy intensity and traffic intensity will aggravate the air pollution and have a decreasing effect on CAPI levels.Urbanisation,financial expenditure and industrial upgrading can effectively improve air quality,and the governance effect on CAPI level decreases in turn.Finally,a Bayesian Dirichlet regression model（Dirinla）was used to investigate the influence mechanism of socio-economic factors on the structure of urban CAPI.The economic development showed an inverted"U"-shaped trend on the proportion of CO,NO₂,O₃,PM₁₀and PM_2.5.Fiscal expenditure effectively reduces the proportion of PM_2.5,PM₁₀and SO₂in CAPI.Industrial intensity has a positive effect on the shares of PM_2.5,PM₁₀,CO,SO₂and NO₂in CAPI.Energy intensity increased the share of carbon and sulphide in CAPI.The level of science and technology has a more significant effect on reducing the share of CO and O₃in CAPI.Population size has a significant positive effect on the share of NO₂and PM_2.5in CAPI.Environmental regulation and the proportion of PM₁₀and NO₂in the CAPI show an"U"curve,and environmental regulation has a significant negative effect on the proportion of PM_2.5in the CAPI.The innovation points of this paper are as follows:（1）From the perspective of research,this paper deeply explores the influence mechanism of socioeconomic factors on the structure of air composite pollution index.Due to the different sources and causes of pollutants,social and economic factors,as the reasons for the promotion/inhibition of pollutants,have positive/negative effects and differences in the impact degree of each component in the air pollution structure.（2）In terms of measurement indicators,this paper constructs a new index CAPI to measure atmospheric composite pollution,which is better than the current international general air pollution index AQI.（3）In terms of research content,the composition data is used to express the structure of air pollution,and the Dirichlet regression model is tried to be introduced into the study of the influence of social and economic factors on air pollution.（4）In terms of research results,this paper attempts to explore the temporal and spatial evolution characteristics of urban air pollution structure in China,and shows the evolution of the types and importance of major pollutants and minor pollutants in the region.