中国目前的空气污染现状

1 Background1 According to statistics from China’s Ministry of Environmental Protection (MEP), cities in China’s Yangtze River Delta, Pearl River Delta, and Beijing-Tianjin-Hebei region suffer over 100 haze days every year, with PM2.5 (particles with an aerodynamic diameter less than 2.5 μm) concentration two to four times above the World Health Organization guidelines. The effects of PM2.5-related air pollution extend beyond haze days, also leading to systemic damage to the health of the human body. At the end of 2011 heated public discussion and media attention over PM2.5 led to its installation as a new national indicator for air quality monitoring, in an era of incredibly high pollution levels and an ever-increasing area of contamination. However, the exact sources of, control approach, public health risks and economic loss due to PM2.5 had yet to be verified and closely studied . This study is the first of its kind, based on currently available research findings and data in relation to PM2.5 in Shanghai, Guangzhou, Xi’an and Beijing, respectively elected as four major cities in Eastern, Southern, Western, and Northern China. It studies the health risks and economic loss linked to PM2.5 in these four cities, and assesses the potential public health and economic benefits given effective improvement of PM2.5 pollution control under different scenarios. Due to a lack of available data, we were only able to estimate the health and economic loss brought upon by premature death. We did not include hospital admissions numbers, nor lost work and school days, although PM2.5 would have also impacted these numbers. We hope that this study can offer insight into evaluating the economic loss due to China’s PM2.5 pollution, and look forward to seeing more researchers and policy makers join the research into PM2.5 and the discussion of pollution control. PM2.5 concentrat ion levels h a v e e n d a n g e re d p u b l i c health in Beijing, Shanghai, Guangzhou and Xi’an. The PM2.5 concentration levels in all four cities exceed World Heath Organisation (WHO) air quality guidelines (AQG). This means higher health risks to the cardiovascular system, cerebrovascular system and an increase in the probability of cancer and premature death. Supposing if pollution levels remained the same as 2010, 8,572 premature deaths would have been caused by PM2.5 in the four cities in 2012, with a total economic loss of 1.08 billion USD . Supposing if the four cities effectively control led PM2.5 levels and met WHO air quality guidelines in 2012, the number of premature deaths would have decreased by at least 81%, wh i le the economic benef i ts of reducing these premature deaths in the four cities would amount to 875 million USD. Key Points 2 The health risks of PM2.52 PM2.5 is small in particulate size but as pollution can reach a large surface area. Compared to other particulate matter it is more prone to carrying a variety of toxic heavy metals, acid oxides, organic pollutants and other chemicals, as well as microorganisms such as bacteria and viruses in the air. Therefore, compared to PM10 it can be considered more hazardous to human health. Modern toxicology research has proven that the heavy metals and PAHs (polycyclic aromatic hydrocarbons) carried by PM2.5 can enter and deposit in human alveoli, causing inflammation and lung diseases. It can also enter the human blood circulation and affect the normal functioning of the human cardiovascular system. Therefore, exposure to PM2.5 can lead to significantly increased mortality due to cardiovascular, cerebrovascular and respiratory diseases, as well as greater cancer risks. (See table 1. WHO air quality guidelines and interim targets for particulate matter – annual mean concentrations ) Table 1. WHO air quality guideline and interim targets for particulate matter – annual mean concentrations PM10 (µg/m 3) PM2.5(µg/m 3) Basis for selected level Interim target - 1 (IT-1) 70 35 These levels are associated with about a 15% higher long-term mortality risk relative to the AQG level. Interim target - 2 (IT-2) 50 25 In addit ion to other health benef i ts, these levels lower the risk of premature mortality by approximately 6% [2-11%] relative to the IT-1 level Interim target -3 (IT-3) 30 15 In addition to other health benefits, these levels lower the mortality risk by approximately 6% [2- 11%] relative to the IT-2 level Air quality guidel ine (AQG) 20 10 These are the lowest levels at which total, cardiopulmonary and lung cancer mortality have been shown to increase with more than 95% confidence in response to long-term exposure to PM2.5 3 Key findings: the health and economic impacts of PM2.5 on four major Chinese cities3 PM2.5 concentration Changes in health outcomes Assessment of health benefits Exposure-response function Willingness to pay (WTP) Exposed population 3.1 Methodology Step 1: Exposure response relationship modeling Step 2: Health losses modeling The cities of Beijing, Xi’an, Shanghai and Guangzhou have been selected for this study. A mathematical model was developed based on PM2.5 laboratory monitoring values over the past three to four years in these four cities, as well as local CDC (Centers for Disease Control and Prevention) statistics on related deaths and their causes over the same period. From this a PM2.5 exposure relative risk coefficient (RR) was calculated. Total deaths related to PM2.5 pollution in 2010 was also estimated based on population sizes and PM10 concentration statistics published in the National Statistical Yearbook 2010. Finally, the study also calculates mortality caused by PM2.5 in 2012, together with figures based on potential PM2.5 improvement scenarios. Those figures include the projected health benefits to these cities under different air pollution levels, according to national guidelines and the WHO AQG. City Monitoring site Monitored period Average daily PM2.5 concentration during monitored period (µg/m3) (standard deviation) Beijing Peking University campus 2006 - 2008 83.96 (58.28) Shanghai Shanghai Environmental Monitoring Center, Pudong District 2004 - 2005 56.4 (1.34) Guangzhou South China Environmental Sciences Institute, Tianhe District 2006 - 2009 59.91 (32.57) Xi’an Chinese Academy of Sciences 2004 - 2008 176.7 (103.8) Table 2. PM2.5 concentration data used in the exposure response relationship model 4 City Health outcomes RR (95% CI) Sources of data Beijing Non-accidental deaths 1.002709 (1.000982, 1.004438) Data for Beijing, 2006 - 2008: Mortality data from National CDC, PM2.5 data from Peking UniversityDeaths caused by circulatory diseases 1.003465 (1.001034, 1.005903) Guangzhou Non-accidental deaths 1.005648 (1.002182, 1.009125) Data for Guangzhou, 2006-2009 data: Mortality data from National CDC, PM2.5 data from South China Institute of Science Deaths caused by circulatory diseases 1.008009 (1.002098, 1.013955) Deaths caused by respiratory diseases 1.00867 (1.001341, 1.016052) Shanghai Non-accidental deaths 1.0036 (1.0011, 1.0061) Kan Haidong, et al (2007) Deaths caused by circulatory diseases 1.0041 (1.0001, 1.0082) Deaths caused by respiratory diseases 1.0095 (0.0016, 0.0173) Xi’an Non-accidental deaths 1.002 (1.0007, 1.0033) Huang Wei, et al (2012) Deaths caused by circulatory diseases 1.0027 (1.0008, 1.0046) Table 3. Exposure response relationship coefficient in the four cities The data in table 2 shows that the daily average PM2.5 concentration far exceeds the national level two, and goes far beyond WHO guidelines. A look at the monitoring results of Xi’an shows levels five times over the national level two standard. From the RR matrix in table 3 we can see that the levels of hazardous impacts are both high in these four cities. 5 Based on the exposure response relationship coefficient values in different cities, we were able to calculate figures for related deaths in 2010 and economic loss based on population and PM2.5 concentration numbers. To calculate the number of residents in 2010 exposed to PM2.5 air pollution, we used statistics from the population of permanent residents in Beijing, Shanghai, Guangzhou and Xi’an (see appendix table 1, from annual statistics reports of each city). The PM2.5 data used is calculated from annual environment communiqués published by the Ministry of Environmental Protection (MEP), with PM10 converted to PM2.5 concentration numbers using a factor of 0.60. The 2010 estimation results are as following, seen in table 4. Detailed figures are listed in the appendix, tables 2-5. 3.2 2010: the health and economic impacts of PM2.5 on four major Chinese cities. 3.3 2012: the health and economic impacts of PM2.5 on four major Chinese cities Table 4. 2010: PM2.5 induced deaths and economic loss estimates City PM2.5 annual concentration (µg/m3) Number of deaths caused by PM2.5 Economic loss (million USD) Beijing 72.6 2349 296 Shanghai 47.4 2980 377 Guangzhou 42 1715 217 Xi’an 78 726 92 PM2.5(µg/m 3) 10 40 Graph 1. PM2.5 concentration levels of Chinese major regions 6 We can also calculate the potential death and economic loss reduction of different air quality improvement scenarios compared to no improvement in 2012 (graphs 2 and 3). The hypothetical air quality levels accord with national standards and the WHO guideline. Detailed figures are listed in the appendix, tables 6-9. Based on the demographic changes of the four cities in 2012, we can calculate deaths and economic loss caused by different levels of PM2.5 in 2012. Since PM10 statistics are taken from the MEP annual environmental communiqués, and those from 2011 and 2012 have yet to be published, we are using 2010 PM2.5 levels as a reference to calculate the impact in 2012. We are supposing PM2.5 in these cities didn’t improve in the past two years. Table 5. 2012: PM2.5 induced deaths and economic loss estimates if pollution remained at 2010 level Graph 2. Reduction of premature death caused by PM2.5 pollution in 2012 under different improvement scenarios City Number of deaths caused by PM2.5 Economic loss (million USD) Beijing 2589 328 Shanghai 3317 420 Guangzhou 1926 244 Xi’an 739 94 BeiJing National Ambient Air Quality Standards (Level2) National Ambient Air Quality Standards (Level1) WHO AQG Reduced Deaths ShangHai GuangZhou XiAn 7 BeiJing ShangHai GuangZhou XiAn National Ambient Air Quality Standards (Secondary) 170 110 41 52 National Ambient Air Quality Standards (Primary) 260 287 157 76 WHO AQG 283 331 186 82 Graph 3. Economic loss reductions under different PM2.5 improvement scenarios .scenarios Economic Benefits millions USD If the pollution level remains at the 2010 level, the total number of deaths resulted from PM2.5 pollution in Beijing in 2012 would be 2,589, and related economic loss would reach nearly 328 million USD. If Beijing can meet level 2 or level 1 of national AQG or the WHO AQG in 2012, such deaths would be reduced by 1,341, 2,054, and 2,233 respectively. There would also be a decrease of 51.7%, 79% and 86.2% respectively over no PM2.5 concentration improvement made (2,589 deaths). And the economic benefits would reach 170, 260 and 283 million USD respectively.A If the pollution level remains at the 2010 level, the total number of deaths resulted from PM2.5 pollution in Shanghai in 2012 would be 3,317, and related economic loss would reach nearly 420 million USD. If Shanghai can meet level 2 or level 1 of national AQG or the WHO AQG in 2012, such deaths would be reduced by 867, 2,267 and 2,617 respectively. There would also be a decrease of 26.1%, 68.3% and 78.9% respectively over no PM2.5 concentration improvement made (3,317 deaths). And the economic benefits would reach 110, 287 and 331 million USD respectively. B If the pollution level remains at the 2010 level, the total number of deaths resulted from PM2.5 pollution in Guangzhou in 2012 would be 1,926, and related economic loss would reach nearly 244 million USD. If Guangzhou can meet level 1 or level 2 of national AQG or the WHO AQG in 2012, such deaths would be reduced by 321, 1,238 and 1,468 respectively. There would also be a decrease of 16.6%, 62.4% and 76.2% respectively over no PM2.5 concentration improvement made (1,926 deaths). And the economic benefits would reach 41, 157 and 186 million USD respectively. C If the pollution level remains at the 2010 level, the total number of deaths resulted from PM2.5 pollution in Xi’an in 2012 would be 739, and related economic loss would reach nearly 94 million USD. If Xi’an can meet level 1 or level 2 of national AQG or the WHO AQG in 2012, such deaths would be reduced by 407, 597 and 644 respectively. There would also be a decrease of 55.1%, 80.8% and 87.1% respectively over no PM2.5 concentration improvement made (739 deaths). And the economic benefits would reach 52, 76 and 82 million USD respectively.D 0 150 200 250 300 350 100 50 In conclusion, if these cities can effectively lower their PM2.5 level and meet level one or two of the national air quality guidelines, PM2.5-induced deaths would be reduced by a significant degree compared to no improvement in 2012. If the cities can meet the WHO AQG such deaths would be reduced by at least 81%, and the economic loss reduction of these four cities could reach in total of up to 868 million USD . Further detailed scenarios for each city 8 Graph 4. PM2.5 source analysis PM2.5 source analysis and control strategy4 PM2.5Sources Coal combustion 19% Nitrogen14% Sulphate17% Combustion of biomass 11% Others 18% Industry 6% Traffic dust 9% Vehicles 6% 4.1 Sources of PM2.5 The composition of PM2.5 is relatively complex, including direct emissions of fine particles of the combustion process (primary PM2.5 particles), and secondary particles generated by multiphase chemical reactions (ie. gases are converted into solids through chemical reactions, such as how sulfur dioxide and nitrogen oxide are converted into sulfates and nitrates) of atmospheric pollutants. Early PM2.5 research focused on PM2.5 sources apportionment for counter measures. A number of studies show that the proportion of primary PM2.5 particles has been on the decrease while that of secondary particles are on the rise.1 Graph 4 shows the analytical results of PM2.5 sources in Beijing by the Chinese Academy of Sciences in 2006. We can see that the emissions of motor vehicles contribute about 6%, the combustion of coal remains the most important source of primary particulate matters, accounting for 19%, and that secondary particles carried by nitrates and sulfates also take a large proportion with 14% and 17%, respectively. This illustrates the significance of pollution caused by secondary particles, especially nitrates and sulfates. 9 4.2 The electric power sector and industrial sectors are the main sources of air pollution Source apportionment method allows for a qualitative analysis of PM2.5 control, with the control of secondary particulate matters being at its core. For pollution control measures, the most crucial approach is to have an inventory of pollutants discharged by different sectors and enterprises. Although there isn’t such an official inventory at the national level in China, scholars have tried several ways to produce one such at both national and regional levels as an important basis for regional joint prevention and control of air pollution. According to the findings published by Zhao Yu et al in 20121 , the country’s emissions by sector are shown in graph 5, and the emissions in the Pearl River Delta (PRD) and the Yangtze River Delta (YRD)shown in graph 62 and graph 73 . Both the national and regional emission inventories indicate that the electric power sector and industrial sectors are the main sources of SO2, NOx, which are precursors to primary and secondary PM2.5 particles. Such a phenomenon is largely attributed to China’s excessive dependence on coal consumption. 1 Zhao, Y., Zhang, J., and Nielsen, C. P.: The effects of recent control policies on trends in emissions of anthropogenic atmospheric pollutants and CO2 i in China, Atmos. Chem. Phys. Discuss. , 12, 24985-25036, doi:10.5194/acpd-12- 24985-2012, 2012 2 C．Huang et al：Emission inventory of anthropogenic air pollutants and VOC species in the Yangtze River Delta region, China，Atmos. Chem. Phys., 11, 4105–4120, 2011 3 Junyu.Zheng et al:A highly resolved temporal and spatial air pollutant emission inventory for the Pearl River Delta region, China and its uncertainty assessment, Atmospheric Environment 43 (2009) 5112–5122 Graph 5. National inventory of different air pollutants in 2010 SO2 NOx CO TSP PM10 PM2.5 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Residential and commercial Transportation Industry Power Plants 10 Graph 6. Yangtze River Delta inventory of different air pollutants in 2007 Graph 7. Pearl River Delta inventory of different air pollutants in 2006 11 A number of studies have shown that worsening urban air pollution and deteriorating regional air quality is closely related to China’s over-reliance on coal consumption. Managing PM2.5 pollution must begin with replacing urban coal consumption with clean alternative energy sources, control of regional total coal consumption, as well as control and treatment of pollutants from coal combustion. China has been making unremitting efforts to do end of pipe air pollution control while developing its economy. However, in spite of such efforts, environmental pressures brought about by drastically increased energy consumption are still looming large. For example, during the 11th Five-Year Plan period, China’s coal consumption increased by 44% (graph 8), accounting for one quarter of the world’s total coal consumption in 2010 . Although desulfurization efforts in the power sector have allowed China to meet its sulfur dioxide emission reduction targets, it still failed to implement de-nitrification plans, which resulted in a 20% increase of nitrogen oxide emission during the 11th Five-Year Plan. This means the only way China’s total nitrogen oxide emissions can return to its 2005 level by 2020 is if the country meets its 10% emission cut targets for both the 12th and 13th Five-Year Plan periods. Which would mean the timeline to control NOx has been postponed by 15 years. Graph 8. Energy consumption during 11th Five-Year Plan 4.3 Growing energy consumption is the main reason for worsening air pollution 12 To effectively combat PM2.5 pollution, to meet China’s new air quality standards, and to protect China’s public health from experiencing further negative impacts due to PM2.5 pollution, we are making the following policy recommendations: To cope with severe air pollution, it would not be enough to simply do end of pipe pollution control. If rapid coal consumption increases cannot be curbed, gains made by the effort to control end of pipe pollutants such as sulfur dioxide and nitrogen oxides emissions during the 12th Five-Year Plan will probably be offset. As China’s coal consumption continues to grow, other pollutants of coal combustion will exacerbate air pollution and interfere with PM2.5 improvements in the long-term. At present, leading cities like Beijing and Guangzhou have already announced their coal consumption reduction target during the 12th Five-Year Plan. The coal consumption growth cap has been introduced to Tianjin, Shanghai and s