Assessing Public Health And Economic Losses Associated With Black Carbon Exposure Levels In China

Coal takes up a large proportion of the energy consumption structure in China.Particles emitted during the combustion process of coal may cause atmospheric pollution.Black carbon（BC）is generated during the incomplete combustion of fossil fuels and biomass.BC has impacts on climate,air quality and public health due to its specific physical and chemical properties.Published findings have simulated BC exposure levels on various scales based on multiple data and methods.Monitoring data is mainly used to asses exposure levels on monitoring sites and personal exposure levels.Satellite remote sensing data can be used for retrieving BC concentrations both on regional and national scales.In addition,models can be used to simulate BC exposure levels both on regional and national scales.However,these methods may have some shortcomings.Due to lack of monitoring data on massive monitoring sites,estimated BC exposure levels in several studies lacked validation.Moreover,most estimated results of BC exposure levels in published findings have low spatio-temporal resolutions.BC pollution in China is relatively severe.Simulating BC short-and long-term exposure levels can provide data base for epidemiological studies and scientific basis for environmental protection administration to enact measures of BC emission reduction.This study simulated short-（1 day）and long-term（1 year）BC exposure levels based on BC monitoring data on 48 monitoring sites and the second Modern-Era Retrospective analysis for Research and Applications（MERRA-2）by using Bayesian Maximum Entropy（BME）from November 2016 to October 2017 in 31 provinces in China.The simulation results were evaluated by Leave-One-Out Cross-Validation（LOOCV）.Based on the simulated BC exposure levels,localized concentration-response coefficients,exposed population and baseline mortality rates,the premature mortalities due to exposure to BC were estimated.Economic losses were estimated based on willingness to pay（WTP）and amended human capital（AHC）.The main conclusions are as follows:（1）BC short-（1 day）and long-term（1 year）exposure levels were simulated during November 2016 to October 2017,with the spatial resolution of 10 km×10 km.BME performed well for estimations of short-（R~2=0.74,RMSE=1.76μg/m~3）and long-term（R~2=0.76,RMSE=1.3μg/m~3）exposure levels.BC annual mean concentration was 1.3μg/m~3（standard deviation:1.3μg/m~3）.The highest BC concentration was presented in Sichuan Basin,with annual mean concentration exceeding 3μg/m~3 in this area.Higher BC concentrations were also presented in the south Beijing-Tianjin-Hebei（BTH）region,central China and northeast China,including southern Hebei,Beijing,Tianjin,Shanxi,western Shandong,Henan,northern Anhui,Hubei,Hunan,and Liaoning Provinces.Low BC concentrations were presented in northwest China and north China,including Xinjiang,Qinghai,Tibet,Inner Mongolia,Gansu and Ningxia Provinces,as well as southeastern coastal areas.BC seasonal mean concentrations ranged by winter（1.8μg/m~3）,autumn（1.3μg/m~3）,spring（1.2μg/m~3）and summer（1.0μg/m~3）.（2）By short-term exposure to BC,premature mortalities due to all-cause diseases,cardiovascular diseases and respiratory diseases were approximately 74,500（95%confidence interval（CI）:23,900–124,500）,37,100（95%CI:8,300–65,400）,and 9,500（95%CI:1,200–17,500）cases,respectively.The corresponding values due to long-term exposure to BC were 538,400（95%CI:495,000–581,300）,257,400（95%CI:229,600–284,800）,and 40,100（95%CI:30,600–49,500）cases,respectively.Premature mortalities were mostly concentrated in the Sichuan Basin,southern part of the BTH region,central China,Jiangsu,Shanghai,and Guangdong Provinces.（3）For short-term exposure to BC,the estimated economic losses caused by all-cause diseases were 90.7 and 51.6 billion RMB based on WTP and AHC,accounted for0.11%and 0.06%of China’s total GDP in 2017（8.27×10~4 billion RMB）,respectively.And the corresponding values due to long-term exposure to BC were 639.2 and 363.7billion RMB,accounted for 0.77%and 0.44%of China’s total GDP.Guangdong and Sichuan Provinces produced the most economic losses due to short-and long-term exposure to BC,respectively.