| Surface ozone(O3)is the third important greenhouse gas,and it has negative impacts on human health and vegetation.In recent decades,China has become one of the global hot spots of O3 pollution.The major air pollutions have been declined in China since 2013,but O3 pollution is becoming more severe.For example,O3 is the primary air pollutant in the Pearl River Delta during 2015-2018.However,many studies focus on O3 pollution in local regions or single city,the works on O3 pollution in all China and meteorological drivers of O3 changes in different seasons are very limited.The negative health impacts caused by O3 pollution are also more and more significant,and the O3 concentrations and the extreme O3 pollution events in China increase.As we know,O3 is mainly generated by photochemical reactions,and meteorology can directly affect the efficiency of generation and accumulation of O3.It is all-important to quantify severity of O3 pollution of all the cities in China and identify of the dominant meteorological mechanisms of O3 changes for knowing the status of O3 pollution and controlling effectively the O3 pollution of each city.The purpose of this paper is to analyze O3 pollution level and quantify the health impacts of O3 pollution by respiratory deaths and calculate the dominant meteorological model and driver of O3 changes for each city from 2015 to 2018,and then assess the he contribution of the global warming to O3 pollution in China in the future.Based on the daily maximum 8-hour moving average(MAD8)dataset of O3 in China during 2015-2018 and the related observed and reanalyzed meteorological data,we build a multiple linear model of MAD8 and meteorology to find the dominant meteorological model and driver of MAD8 changes in each city.At the same times,we use the meteorological model and the model meteorological data of the Coupled Model Intercomparison Project Phase 5(CMIP5)to predict O3 pollution changes in China in the future.The main work and conclusions are as follows:(1)This paper analyzes the distribution of O3 pollution days(MDA8≥160μg/m3)of each city.During 2015-2018,annual O3 pollution days of 71%of the cities have an increased trend,which shows that the O3 pollution in China is becoming more severe.The Beijing-Tianjin-Hebei urban agglomeration in northern China has the most severe O3 pollution among the six study areas,which regional O3 pollution days are 231 days,and the average MDA8 of pollution days is 195.49 μg/m3.(2)Based on the constant assumptions of the same demographic data,baseline daily respiratory mortality,we quantify respiratory deaths attributable to O3 pollution in 358 cities.During 2015-2018,O3 pollution causes 208,070 respiratory deaths in China,and the regional deaths caused by O3 pollution are very prominent.The result shows that increasing O3 pollution in China causes significant health influences.(3)This paper uses Bayesian Information Criterion to build the optimal multiple linear model of MDA8 and meteorological variables to find the dominant model and driver of the each city.We find the model including temperature(daily maximum 2meter air temperature,daily sunshine duration(SD)and daily specific humidity(SH)is the dominant meteorological model of MDA8 in spring,summer and fall,while the dominant model in summer includes temperature,SH and daily 10-meter meridional wind(V10M).Moreover,temperature and SD are the main meteorological drivers of MDA8 in four seasons in China.The dominant influence of temperature expands from the northern China to the southern China in spring and summer,which influence peaks in summer and falls back to northern China in fall.The influence of temperature is the smallest in winter,while the dominant influence changes of SD are the opposite.Temperature is the dominant meteorological driver of MDA8 the most of cities in China,and the heat wave plays an all-important role of O3 pollution.(4)In order to assess the impact of global warming on O3 pollution,we use the meteorological model and the simulated meteorological data from CMIP5 to predict O3 pollution in China during 2019-February 2100.In high emission scenario(RCP8.5 scenario)with no climate policy,the annual O3 pollution days of 85%of the cities have a statistically significant increased trend,and the regional O3 pollution will be more severe.Due to increasing heat waves since 2015,O3 pollution in China is becoming worst,and health impacts of O3 pollution is also more and more prominent.In RCP8.5 scenario,the much higher O3 pollution by 2099 indicates that climate penalty can dramatically exacerbate O3 pollution in China.Overall,these results suggest that climate penalty can exacerbate O3 pollution in China in recent years.When formulating effective policy to control O3 pollution,the government needs to pay an attention to the contribution of meteorology to O3 pollution. |
