Health Risk Assessment Of PM_2.5 And O₃ In China

Air pollution in China has been very serious during recent decades.Epidemiological studies have shown that fine particulate matter(PM_2.5)and ozone（O₃）have adverse effects on human health.However,rare studies have investigated the effects of short-term exposure to PM_2.5 and O₃ on daily outpatient visits for respiratory diseases or mortality in Shanghai.For PM_2.5,the most harmful PM_2.5 components and their sources are still unclear,and it is impossible to accurately quantify the health hazards of fine particles.Quantifying the future health burden attributed to PM_2.5 and O₃ in China is challenging when jointly accounting for emissions,climate and population changes.The purpose of this study was to analyze the relationship between short-term exposure to PM_2.5 and O₃ and daily outpatient/daily death in Shanghai.To assess the relationship between short-term exposure to PM_2.5 components(organic carbon（OC）,elemental carbon（EC）,nitrate（NO₃^-）,ammonium（NH₄⁺）and sulfate(SO₄^2-)and daily death in Shanghai.To calculate the disease burden of the most toxic component EC in PM_2.5 and of EC from six different sources（residential sources,industrial sources,transportation sources,open-air biomass burning,electricity sources and other sources）,and determine the largest contributing source of EC.Forecast the disease burden and year of lost（YLL）caused by PM_2.5 and O₃ from 2010 to 2050 in the future.The generalized linear model（GLM）was applied to analyze the exposure-response relationship between air pollutants(daily average PM_2.5 and daily maximum 8-h average O₃),and daily outpatient visits of respiratory diseases.The sensitivities of male and female at the ages of 15-60 yr-old and 60+yr-old to the pollutants were also studied for the whole year and for the cold and warm months,respectively.Finally,the results of the single-day lagged model were compared with that of the moving average lagged model.Similarly,the generalized linear model（GLM）was used to study the impact of pollutants in Shanghai from January 1,2013 to December 31,2015 on the number of deaths from different causes.The PM_2.5 components(OC,EC,NO₃^-,NH₄⁺and SO₄^2-)concentrations simulated by the community multi-scale air quality model（CMAQ）were used to analyze the relationship between short-term exposure to PM_2.5components and daily deaths in Shanghai.We estimated premature mortality attributed to EC in China in 2013 using a health impact model combined with predicted annual average EC concentrations from the Community Multi-Scale Air Quality（CMAQ）model.Source contributions to EC from six different source sectors were also estimated with the source-oriented technique,includingresidential,industrial,transportation,open burning,power,and other sources.The sensitivity of premature mortality to EC was quantified to determine the sources which could effectively reduce the EC associated premature mortality in different regions of China.we used the Goddard Earth Observing System chemical transport model（GEOS-Chem）to project PM_2.5 and O₃ concentrations from 2010 to 2050 under four Representative Concentration Pathway scenarios（RCPs）,then projected the PM_2.5 and O₃-related premature mortality and years of life lost（YLL）in this period.The RR of respiratory outpatients increased by 0.37%with a 10μg/m³ increase in PM_2.5.Exposure to PM_2.5（RR,1.005,95%CI,1.003-1.006）was more sensitive for females than for male（RR,1.003,95%CI,1.001-1.004）,and was more sensitive for the 15-60 yr-old（RR,1.004,95%CI,1.002-1.006）than the 60+yr-old age group（RR,1.003,95%CI,1.001-1.005）.O₃ was not significantly associated with respiratory outpatient visits during the warm periods,but was negatively associated during the cold periods.PM_2.5 was more significantly in the cold periods than that in the warm periods.PM_2.5 had a significant effect on all-cause mortality,and a 10μg/m³ increase leads to 0.7%increase in all-cause mortality（RR,1.007,95%CI,1.001-1.012）.For PM_2.5,for every 10μg/m³increase,the mortality rate of respiratory diseases increases by 1.9%（RR,1.019,95%CI:1.003-1.035）.For O₃,every increase of 10μg/m³ resulted in a 0.8%increase in all-cause mortality（RR:1.008,95%CI:1.001-1.015）.The mortality rate of circulatory diseases increased by 1.1%（RR:1.011,95%CI:0.999-1.021）.The total all-cause premature mortality caused by EC was about 1 436 957（95%CI:998746-2 029 210）in China in 2013.Henan had the largest number of deaths of 161 252（95%CI:113 067-224 682）.Residential and industrial sources were the two main sources of EC-induced premature mortality,resulting in 915 031（95%CI:627 254-1 317 654）（60.0%）and 326 765（95%CI:220 012-482 996）（19.6%）deaths,respectively.Compared to the targeted year 2050,we found that PM_2.5concentrations changed between-31.5%to 14.5%since 2010,resulted in-13.5%to 9.4%change in PM_2.5-related mortality and-25.7%to 0.6%change in YLL across all the RCPs scenarios.For O_3,the concentrations varied-13.3%to 3.7%by 2050,contributing to-26.9%to 13.1%change in O₃-related mortality and-48.8%to 4.0%change in YLL.The lowest health impacts occurred in the RCP4.5 scenario by2050 for both pollutants.Conclusions:PM_2.5 and O₃ have varying degrees of risk to outpatients and deaths.China needs to take more active mitigation measures for PM_2.5 and O₃ pollution.Although there were uncertainties in the estimation,it was suggested that the reduction of EC in China will bring significant health benefits,and the control of industrial and transportation sources will effectively reduce the premature deaths caused by EC in China.In addition,RCP4.5 was the scenario with the lowest death toll related to PM_2.5 and O₃ in the future.Controlling pollutant emissions under future climate change will has huge health benefits.