Urban Air Quality Level Measurement And Population Exposure Risk Assessment In Northeast China

Global climate change and air pollution have become serious problems affecting human production and life.With the rapid development of China’s economy,industrialization and urbanization,people’s living standards have been improved,but at the same time,it has brought serious environmental pollution.Air pollution control is imminent.Northeast China is an important industrial base in China.Air pollution has typical regional characteristics.It has long been dominated by heavy industry development.Seasonal air pollution problems are prominent.Compound air pollution problems not only cause great distress to people’s daily life,but also have serious harm to human health.Therefore,it is of great theoretical and practical significance to evaluate the spatial and temporal distribution characteristics of air pollutants and population exposure risk.It is of great significance to evaluate the spatial and temporal heterogeneity of air quality in prefecture-level cities in Northeast China for the differential prevention and control of urban air pollution.In this study,the air quality index（AQI）and air pollution concentration data of six pollutants(PM_2.5,PM₁₀,SO₂,NO₂,CO,O₃)in 36prefecture-level cities in the three northeastern provinces from 2015 to 2019 were used.Spatial autocorrelation,social network analysis,random forest model and other methods were used to analyze the spatial and temporal distribution differences of air pollutants and their driving factors.The results show that:（1）From the perspective of time scale,the analysis of the annual average concentration of air pollution in the three northeastern provinces from 2015 to 2019shows that the overall air quality in Heilongjiang Province is better than that in Jilin Province and Liaoning Province.Compared with 2015,in 2019,except for O₃,which fluctuated in five years and the annual average concentration value was relatively high,the concentration values of other pollutants showed a downward trend,indicating that the air quality was developing well.From the perspective of pollutant types,the top three pollutants are PM_2.5,PM₁₀and O₃,indicating that the current pollution is mainly compound.The concentrations of PM_2.5,PM₁₀,SO₂,NO₂and CO were higher in winter and lower in summer,while O₃was opposite.Except for O3,the high values of the six pollutants appeared in December,January and February,which were roughly’U’-shaped,and the highest values of O₃appeared in May,June and July,showing an inverted’U’-shaped distribution.From the perspective of spatial scale,the overall aggregation distribution of air quality in Northeast China is obvious.The high-value areas of pollution are mainly distributed in the south and large cities,and the low-value areas are mainly distributed in the north and marginal cities.（2）The social network analysis method is used to analyze the spatial network correlation of air quality index（AQI）in 2019.By establishing the network analysis diagram of 36 node cities of AQI,it is found that there is an obvious’core-periphery’structure between cities,and the spillover relationship is complex.Harbin,Changchun,Siping,Shenyang,Tieling and Anshan are located in the center of the network,which have strong correlation with other cities.The overall network structure is closely related and has good connectivity.There are no isolated nodes in each node city.Each node city has more spillover paths,and the spatial network structure is more complex and stable.From the perspective of spatial clustering characteristics,the first plate cities are mainly located in the southern part of the northeast region,the second plate cities are mainly concentrated in the central part of the northeast region,and the third and fourth plates are mainly concentrated in the north,with less pollution.（3）Among the natural influencing factors,the annual average temperature has the greatest impact on AQI and four pollutants except CO and NO₂,and the annual average wind speed and vegetation index have a greater impact on SO₂.Among the socio-economic influencing factors,the industrial structure（the proportion of added value of secondary industry in GDP）has a greater impact on SO₂,CO and NO₂,and the impact intensity ranks second.The impact of power consumption（electricity consumption of the whole society）is second only to the industrial structure;traffic factors（per capita urban road area）and electricity consumption（total electricity consumption）have the greatest impact on CO and NO₂,respectively.（4）The population exposure risk index model was constructed by using the population grid data and the concentration of atmospheric pollutants,and the population exposure risk of various pollutants was analyzed.The overall situation showed that the northeast plain was the main high-risk area,and the temporal and spatial evolution law of population exposure risk was revealed.The influencing factors of population exposure risk were qualitatively analyzed in combination with the research results of domestic and foreign scholars.