Consumption Based Source Apportionment Indicates Different Regional Contributions to O3 Concentrations and Health Effects

China is confronting aggravated ozone(O_(3))pollution,leading to adverse health impacts.This study quantifies the regional contributions to O_(3)in China using two approaches;estimating(1)where goods are produced(the production method),and(2)where goods are consumed(the consumption method).The production method predicts higher local source contribution than the consumption method;this difference can be attributed to exports.Occurrence of high-O_(3)episodes suggests a major contribution to O_(3)concentration as a result of trade activities.Based on the consumption method,9219 out of 18532 daily premature mortalities were caused by local sources in north China,while it increased to 14471 of the production method when neglecting contributions due to export and consumption in other regions.This study suggests that O_(3)control should consider both where goods are consumed and emissions are emitted,especially taking account of international trade activities.

The 2022 report of synergetic roadmap on carbon neutrality and clean air for China:Accelerating transition in key sectors

China is now confronting the intertwined challenges of air pollution and climate change.Given the high synergies between air pollution abatement and climate change mitigation,the Chinese government is actively promoting synergetic control of these two issues.The Synergetic Roadmap project was launched in 2021 to track and analyze the progress of synergetic control in China by developing and monitoring key indicators.The Synergetic Roadmap 2022 report is the first annual update,featuring 20 indicators across five aspects:synergetic governance system and practices,progress in structural transition,air pollution and associated weather-climate interactions,sources,sinks,and mitigation pathway of atmospheric composition,and health impacts and benefits of coordinated control.Compared to the comprehensive review presented in the 2021 report,the Synergetic Roadmap 2022 report places particular emphasis on progress in 2021 with highlights on actions in key sectors and the relevant milestones.These milestones include the proportion of non-fossil power generation capacity surpassing coal-fired capacity for the first time,a decline in the production of crude steel and cement after years of growth,and the surging penetration of electric vehicles.Additionally,in 2022,China issued the first national policy that synergizes abatements of pollution and carbon emissions,marking a new era for China's pollution-carbon co-control.These changes highlight China's efforts to reshape its energy,economic,and transportation structures to meet the demand for synergetic control and sustainable development.Consequently,the country has witnessed a slowdown in carbon emission growth,improved air quality,and increased health benefits in recent years.

MEIC-global-CO_(2):A new global CO_(2)emission inventory with highly-resolved source category and sub-country information

CO_(2)emission inventory provides fundamental data for climate research and emission mitigation.Currently,most global CO_(2)emission inventories were developed with energy statistics from International Energy Agency(IEA)and were available at country level with limited source categories.Here,as the first step toward a high-resolution and dynamic updated global CO_(2)emission database,we developed a data-driven approach to construct seamless and highly-resolved energy consumption data cubes for 208 countries/territories,797 sub-country administrative divisions in 29 countries,42 fuel types,and 52 sectors,with the fusion of activity data from 24 international statistics and 65 regional/local statistics.Global CO_(2)emissions from fossil fuel combustion and cement production in 1970–2021 were then estimated with highly-resolved source category(1,484 of total)and sub-country information(797 of total).Specifically,73%of global CO_(2)emissions in 2021 were estimated with sub-country information,providing considerably improved spatial resolution for global CO_(2)emission accounting.With the support of detailed information,the dynamics of global CO_(2)emissions across sectors and fuel types were presented,representing the evolution of global economy and progress of climate mitigation.Remarkable differences of sectoral contribution were found across sub-country administrative divisions within a given country,revealing the uneven distribution of energy and economic structure among different regions.Our estimates were generally consistent with existing databases at aggregated level for global total or large emitters,while large discrepancies were observed for middle and small emitters.Our database,named the Multiresolution Emission Inventory model for Climate and air pollution research(MEIC)is publicly available through http://meicmodel.org.cn with highly-resolved information and timely update,which provides an independent carbon emission accounting data source for climate research.

全球变暖导致易诱发臭氧污染的强地面太阳辐射频率增加

世界卫生组织2021年提出了新的臭氧标准,不仅加严了原有的短期暴露标准,还增加了暖季峰值的长期暴露指标.2019年秋季我国发生了大范围臭氧污染事件,特别是珠三角地区臭氧浓度异常增加最为突出,导致其暖季峰值超标,并且2019年长时间臭氧污染事件增幅更大.本文发现地面太阳辐射与臭氧年际变化相关性远高于其他气象因子,即使在温度较低时,较强的太阳辐射依然可促进高臭氧浓度累积.数值模式显示强太阳辐射驱动天然源大幅增加,不仅促进臭氧浓度升高,更重要的是,对于长时间臭氧污染事件频率增加大于短期污染事件,从而大大促进臭氧超标天数的增加.结合高分辨率地球系统模式和多模式比较计划,一致揭示在全球变暖下中国东部、美国东南部、欧洲各国,未来地面太阳辐射显著增加.通过将秋季地面太阳辐射日异常标准化,构建了臭氧气象指数,可有效揭示高臭氧浓度,阐明在北半球多个易发生臭氧污染区域,高臭氧气象指数天气发生频率显著增加,即利于高臭氧污染发生的气象条件在全球变暖下可能会更加频繁地发生.

Synergetic roadmap of carbon neutrality and clean air for China

It is well recognized that carbon dioxide and air pollutants share similar emission sources so that synergetic policies on climate change mitigation and air pollution control can lead to remarkable co-benefits on greenhouse gas reduction,air quality improvement,and improved health.In the context of carbon peak,carbon neutrality,and clean air policies,this perspective tracks and analyzes the process of the synergetic governance of air pollution and climate change in China by developing and monitoring 18 indicators.The 18 indicators cover the following five aspects:air pollution and associated weather-climate conditions,progress in structural transition,sources,inks,and mitigation pathway of atmospheric composition,health impacts and benefits of coordinated control,and synergetic governance system and practices.By tracking the progress in each indicator,this perspective presents the major accomplishment of coordinated control,identifies the emerging challenges toward the synergetic governance,and provides policy recommendations for designing a synergetic roadmap of Carbon Neutrality and Clean Air for China.

Air pollution health burden embodied in China's supply chains

Product trade plays an increasing role in relocating production and the associated air pollution impact among sectors and regions.While a comprehensive depiction of atmospheric pollution redistribution through trade chains is missing,which may hinder targeted clean air cooperation among sectors and regions.Here,we combined five state-of-the-art models from physics,economy,and epidemiology to track the anthropogenic fine particle matters(PM_(2.5))related premature mortality along the supply chains within China in 2017.Our results highlight the key sectors that affect PM_(2.5)-related mortality from both production and consumption perspectives.The consumption-based effects from food,light industry,equipment,construction,and services sectors,caused 2e22 times higher deaths than those from a production perspective and totally contributed 63%of the national total.From a cross-boundary perspective,25.7%of China's PM_(2.5)-related deaths were caused by interprovincial trade,with the largest transfer occurring from the central and northern regions to well-developed east coast provinces.Capital investment dominated the cross-boundary effect(56%of the total)by involving substantial equipment and construction products,which greatly rely on product exports from regions with specific resources.This supply chain-based analysis provides a comprehensive quantification and may inform more effective joint-control efforts among associated regions and sectors from a health risk perspective.

Air pollution characteristics and their relationship with emissions and meteorology in the Yangtze River Delta region during 2014–2016

With rapid economic growth and urbanization, the Yangtze River Delta(YRD) region in China has experienced serious air pollution challenges. In this study, we analyzed the air pollution characteristics and their relationship with emissions and meteorology in the YRD region during 2014–2016. In recent years, the concentrations of all air pollutants, except O3,decreased. Spatially, the PM2.5, PM10, SO2, and CO concentrations were higher in the northern YRD region, and NO2 and O3 were higher in the central YRD region. Based on the number of non-attainment days(i.e., days with air quality index greater than 100), PM2.5 was the largest contributor to air pollution in the YRD region, followed by O3, PM10, and NO2.However, particulate matter pollution has declined gradually, while O3 pollution worsened.Meteorological conditions mainly influenced day-to-day variations in pollutant concentrations. PM2.5 concentration was inversely related to wind speed, while O3 concentration was positively correlated with temperature and negatively correlated with relative humidity.The air quality improvement in recent years was mainly attributed to emission reductions.During 2014–2016, PM2.5, PM10, SO2, NOx, CO, NH3, and volatile organic compound(VOC)emissions in the YRD region were reduced by 26.3%, 29.2%, 32.4%, 8.1%, 15.9%, 4.5%, and0.3%, respectively. Regional transport also contributed to the air pollution. During regional haze periods, pollutants from North China and East China aggravated the pollution in the YRD region. Our findings suggest that emission reduction and regional joint prevention and control helped to improve the air quality in the YRD region.

Rapid improvement of PM2.5 pollution and associated health benefits in China during 2013–2017

Exposure to fine particulate matter(PM2.5)is known to harm public health.In China,after implementation of aggressive emissions control measures under the Action Plan of Air Pollution Prevention and Control(2013-2017),air quality has significantly improved.In this work,we investigated changes in PM2.5 exposure and the associated health impacts in China for the period 2013-2017.We used an optimal estimator of PM2.5 combining in-situ observations,satellite measurements,and simulations from a chemical transport model to derive the spatial and temporal variations in PM2.5 exposure,and then used welldeveloped exposure-response functions to estimate the premature deaths attributable to PM2.5 exposure.We found that national population-weighed annual mean PM2.5 concentrations decreased from 67.4μgm-3 in 2013 to 45.5μgm-3 in 2017(32%reduction).This rapid decrease in PM2.5 pollution led to a 14%reduction in premature deaths due to long-term exposure.We estimated that,during 2013-2017,the premature deaths attributable to long-term PM2.5 exposure decreased from 1.2 million(95%CI:1.0,1.3;fraction of total mortality:13%)in 2013 to 1.0 million(95%CI:0.9,1.2;10%)in 2017.Despite the rapid decrease in annual mean PM2.5 concentrations,health benefits associated with reduced long-term exposure were limited,because for many cities,the PM2.5 levels remain at the portion where the exposure-response function is less steeper than that at the lowconcentration end.We also found that the deaths associated with acute exposure decreased by 61%during 2013-2017 due to rapid reduction in the number of heavily polluted days.Our results confirm that clean air policies in China have mitigated the air pollution crisis;however,continuous emissions reduction efforts are required to protect citizens from air pollution.

Impact of China’s Air Pollution Prevention and Control Action Plan on PM2.5 chemical composition over eastern China

China promulgated the Air Pollution Prevention and Control Action Plan(the Action Plan)in 2013 and developed stringent control measures to mitigate fine particulate matter(PM2.5) pollution.Here,we investigated the PM2.5 chemical composition changes over eastern China associated with the Action Plan during 2013-2017 using satellite-based PM2.5 chemical composition data derived using CMAQ simulations and satellite inputs.The PM2.5 concentrations decreased considerably during this time as a result of the reductions in all chemical species in PM2.5.The population-weighted mean concentrations over eastern China decreased from 11.1 to 6.7μgm-3 for SO42-,13.8-13.1μgm-3 for NO3-,7.4-5.8μgm-3 for NH4+,9.9-8.4μgm-3 for OM,4.6-3.8μg m-3 for BC and 12.9-9.6μg m-3 for other species in PM2.5.SO42-had the largest reduction of 40%,while NO3-had the lowest reduction of 5%,resulting in a greater fraction of NO3-and a smaller fraction of SO42-in PM2.5.Among the three key regions,Beijing-Tianjin-Hebei had the largest reduction in PM2.5 and its chemical compositions.The decrease in SO42-concentrations was in line with the reduction of SO2 emissions,and the major driver of the SO2 emission reductions was the industrial sector.The decrease in NO3 concentrations was limited because the decrease in SO2 emissions and the stable NH3 emissions facilitated the formation of NO3-from HNO3,which partially offset the reduction in NOx emissions driven by the power sector.To mitigate PM2.5 pollution more effectively,future efforts are needed to reduce NH3 emissions.

Mapping anthropogenic emissions in China at 1 km spatial resolution and its application in air quality modeling

New challenges are emerging in fine-scale air quality modeling in China due to a lack of high-resolution emission maps.Currently,only a few emission sources have accurate geographic locations(point sources),while a large part of sources,including industrial plants,are estimated as provincial totals(area sources)and spatially disaggregated onto grid cells based on proxies;this approach is reasonable to some extent but is highly questionable at fine spatial resolutions.Here,we compile a new comprehensive point source database that includes nearly 100,000 industrial facilities in China.We couple it with the frame of Multi-resolution Emission Inventory for China(MEIC),estimate point source emissions,combine point and area sources,and finally map China’s anthropogenic emissions of 2013 at the spatial resolution of 30’’*30’’(~1 km).Consequently,the percentages of point source emissions in the total emissions increase from less than 30%in the MEIC up to a maximum of 84%for SO_(2)in 2013.The new point source-based emission maps show the uncoupled distribution of emissions and populations in space at fine spatial scales,however,such a pattern cannot be reproduced by any spatial proxy used in the conventional emissions mapping.This new accurate high-resolution emission mapping approach reduces the modeled biases of air pollutant concentrations in the densely populated areas compared to the raw MEIC inventory,thus improving the assessment of population exposure.

Impact of clean air action on PM2.5 pollution in China

China suffers from severe air pollution in the past decades,characterized by high-levels of fine particulate matter(PM2.5)concentrations.To mitigate PM2.5 pollution,the Chinese government issued the Air Pollution Prevention and Control Action Plan(referred to as the Clean Air Action hereinafter)in 2013,which requires the three key regions,ie..,Beijing-Tianjin-Hebei(BTH),the Yangtze River Delta(YRD)and the Pearl River Delta(PRD),to reduce PM2.5 concentrations by 15-25%from 2013-2017,and all other cities to reduce PM10 concentrations by 10%compared to 2012(State Council of the People's Republic of China,2013).

Attribution of PM_(2.5) exposure in Beijing-Tianjin-Hebei region to emissions:implication to control strategies

The Beijing-Tianjin-Hebei （BTH） region is one of the most heavily polluted regions in China, with both high PM2.5 concentrations and a high population density. A quantitative source-receptor relationship can provide valuable insights that can inform effective emission control strategies. Both source appor- tionment （SA） and source sensitivity （SS） can provide such information from different perspectives. In this study, both methods are applied in northern China to identify the most significant emission cate- gories and source regions for PMz5 exposure in BTH in 2013. Despite their differences, both models show similar distribution patterns for population and simulated PM2.5 concentrations, resulting in overall high PM2.5 exposure values （approximately 110 Ixg/m3） and particularly high exposure values during the win- ter （approximately 200 ktg/m3）. Both methods show that local emissions play a dominant role （70%）, with some contribution from surrounding provinces （e.g., Shandong） via regional transport. The two methods also agree on the priority of local emission controls： both identify industrial, residential, and agricultural emissions as the top three categories that should be controlled locally. In addition, the effect of control- ling agricultural ammonia emissions is approximately doubled when the co-benefits of reducing nitrate are considered. The synthesis of SA and SS for addressing specific categories of emissions provides a quantitative basis for the development of emission control strategies and policies for controlling PM2.5 in China.

Formation of secondary inorganic aerosol in a frigid urban atmosphere

Formation of secondary inorganic aerosol(SIA)was investigated during a six-month long heating season in Harbin,China.Enhanced sulfate formation was observed at high relative humidity(RH),with the same threshold RH(80%)for both colder and warmer measurement periods.Compared to wintertime results from Beijing,the threshold RH was considerably higher in Harbin,whereas the RH-dependent enhancement of sulfur oxidation ratio(SOR)was less significant.In addition,the high RH events were rarely encountered,and for other periods,the SOR were typically as low as~0.1.Therefore,the sulfate formation was considered inefficient in this study.After excluding the several cases with high RH,both SOR and the nitrogen oxidation ratio(NOR)exhibited increasing trends as the temperature increased,with the increase of NOR being sharper.The nitrate to sulfate ratio tended to increase with increasing temperature as well.Based on a semi-quantitative approach,this trend was attributed primarily to the temperature-dependent variations of precursors including SO_(2) and NO_(2).The influence of biomass burning emissions on SIA formation was also evident.With stronger impact of biomass burning,an enhancement in NOR was observed whereas SOR was largely unchanged.The different patterns were identified as the dominant driver of the larger nitrate to sulfate ratios measured at higher concentrations of fine particulate matter.