中国与世界,环境危机大家谈

china and the world discuss the environment

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sqandrews

加入本网站时间 Member Since 11 December 2011

Sqandrews's 评论 comments

谢谢,bingo

我同意社会在推动空气质量标准以更好地保护公众的事情上可以扮演很重大的角色。但是,我认为对问题的严重性和影响的保守态度,不管是从短期的角度还是长远的角度看,直到现在一直都阻止着中国公众扮演该角色。中国确实有能力以最小的代价减少显著的空气污染,污染对健康的影响远比这些代价重得多,而最重要的问题之一就是中国缺少行动来执行现有的排放标准。

Thanks, bingo

I agree the society could potentially play a large role in pushing for air quality standards that better protect the public. However, I believe the understatement of the severity and effects of both short and long term pollution levels has, until recently, prevented the Chinese public from being able to take this role. China does have the capacity to significantly reduce air pollution at minimal costs that are far outweighed by the health impacts, but one of the significant problems is lack of enforcement of existing Chinese emissions standards.

基于北京政府数据的分析

你好,dlming。我在我的文章中指出了我所列数据的两个主要来源:1)24小时日均PM2.5浓度,使用BAM 1020 FES PM2.5过滤器,位于朝阳区美国大使馆楼顶;2)公布的日均空气污染指数值,由北京市环保局公布,这些数值用政府的算法转换成了PM10的浓度。
就一般的空气质量标准和专门的公开报告而言,如世界卫生组织(WHO)建议,两者在绝大多数国家中是设计“用以保护公众健康的”。《2005年世界卫生组织指南》已颁布近七年,其中清晰地指出,“实现指南中规定的参考值应该是所有地区空气质量管理和降低健康危害的终极目标。” 即使是七年前也很清楚,“对健康的不利影响范围不断扩大,这与含更微小颗粒物的空气污染有关。”
在北京PM2.5与PM10的比例出奇的高,达85%。如世界卫生组织指出的:“在设置地方标准时,假设相关数据有效,可以采用与此比例不同的数值,如果该数值能更好地反应当地的情况。”这也是中国标准和报告弱化空气污染的健康影响的另外一个原因。按已过时的《世界卫生组织2005指南指南》,我取年均PM2.5浓度为35ug/m3,那么暂行的年均PM10浓度的指导数值就是其两倍即70ug/m3。然而,因为在北京PM2.5至少约是PM10的85%,年平均PM10浓度约为41ug/m3就能达到世界卫生组织暂行指南的1级标准,这只是一个临时的数值,应该会设立新的标准。然而,中国目前年均PM10标准是100ug/m3,这远比世界卫生组织1号暂行指南规定的75ug/m3高的多,正如你所指出的,这个数字基于假设的50%比例,对北京来说是不准确的,那里PM2.5构成了PM10分数里分子的很大一部分。

Analysis based on Beijing government data

Greetings dlming, I identify in my article the two main sources of my data: 1) 24 hour daily average PM2.5 concentrations as measured by the BAM 1020 FES PM2.5 filter atop the US Embassy in Chaoyang, and 2) publicly reported daily average air pollution index values, reported by the Beijing Environmental Protection Bureau, which are the converted into PM10 concentrations based government methodologies.

In terms of air quality standards, generally, and public reporting, specifically, they are designed in most countries, as the WHO reccomends, "to protect the public health." The WHO 2005 guidelines, which are now nearly 7 years old, make clear that "[p]rogress towards the guideline values should [...] be the ultimate objective of air quality management and health risk reduction in all areas." Even back then it was clear that "an increasing range of adverse health effects has been linked to air pollution, and at ever-lower concentrations."

The ratio of PM2.5 to PM10 in Beijing at .85 is shockingly high. As the WHO notes: "When setting local standards, and assuming the relevant data are available, a different value for this ratio, i.e. one that better reflects local conditions, may be employed." This is yet another reason why the Chinese standards and reporting understate the health impacts. ie the now dated WHO 2005 interim I target annual average PM 2.5 concentration is 35ug/m3 and the annual average interim PM 10 concentration guideline is twice that at 70ug/m3. However, because in Beijing at least, PM2.5 is ~85% of PM10, an annual average PM10 standard of around 41ug/m3 would consistent with the interim-1 level WHO guidelines, which should be temporary until higher standards are set. Yet, currently the Chinese annual average PM10 standard is 100 ug/m3. This is far more than the WHO interim I guideline of 75ug/m3, and as you note, this number is based on an assumed ratio of 50% which is inaccurate for Beijing where PM2.5 constitutes such a large fraction of PM10.

感谢您的评论

如果您有任何疑问,请让我知道。

Thanks for your comments.

Please let me know if you have any questions.

杜少中 (北京环保局12月6日)(微波转发)

杜少中 (北京环保局12月6日)(转发):这是几年前的话题,里面要说太多。我只建议你客观的看这个文件,就不难发现一些显而易见的问题,其他可慢慢讨论。提示一下:一,北京空气质量达标天1998年以来一直没有达到超过80%。二,颗粒物年日均浓度也从来没有达到国家标准。

Du Shaozhong (Beijing Environmental Protection Bureau 6 December) (Weibo Repost)

Du Shaozhong (Beijing Environmental Protection Bureau, 6 December) (reposting): This is a topic that has been around for a few years, and there is much on it that I wish to discuss. I just recommend that if you look at this article impartially, you can clearly see the problem, the rest can be discussed more slowly. Let me present this: first, since 1998 Beijing's air quality has failed to come up to standard 80% of the time. Second, yearly and daily average particulate matter concentrations have never achieved the national standard.

流行病学研究和健康风险

谢谢你的提问。但是很不幸,就像你意识到的那样无论是长期还是短期北京如此高浓度的PM2.5还是存在很多不确定的东西。
1)10月10号到10月11号的24小时平均PM2.5浓度是大约102。去年平均PM2.5浓度是大约105,而今年前10个月是大约99。然而,去年的数据很可能有一点高(不会高太多)因为年初的数据丢失了,而且年初的浓度可能比较低。同样,我相信今年的平均浓度结果会高一些,如果包括11月和12月的话。注意,比如在美国,制定PM2.5标准的时候是基于三年的平均值,甚至同一区域检测器的数据也会相差几个百分点。
2)请注意我这里用了“可能增长”这个词。发表在《新英格兰医学杂志》的蒲伯的研究(http://www.nejm.org/doi/full/10.1056/NEJMsa0805646#)用的方法是基于美国51个不同地区5年的平均PM2.5数据,分别是从1979年到1983年,以及1997年到2001年。即使在1979年到1983年这个时间段美国的最高PM2.5浓度也只有大约30。因此,类似科恩等所作的具有影响力的研究(已经发表)http://ehs.sph.berkeley.edu/krsmith/Publications/Chapt%2017%20Urban%20outdoor%20air.pdf 把城市最高浓度PM2.5设为50。尤其是有详细分析估计北京80%以上的区域暴露在交通污染源附近http://www.healtheffects.org/International/Jerrett_Asia_Traffic_Exposure.pdf 我推测在这个水平以上可能有一些影响(部分取决于机动车排放的事实)。其他研究也发现年平均PM2.5浓度降低10ug/m3,人的寿命可以增加几个月到一年(芬兰研究发下PM2.5每增长10,人均寿命就会下降1.3年)。《新英格兰医学杂志》发表的Krewenski 的社论说PM2.5每下降10ug/m3,人均寿命就会增加0.77年。http://www.nejm.org/doi/full/10.1056/NEJMe0809178 因此,我相信从蒲伯和其他人的研究中可以得出一个合理的结论,就是如果PM10减少85ug/m3,人均寿命就会增长5年以上,不过也承认可能存在一些不确定性。(0.77乘以8.5等于6.5,但由于上面描述的哪些因素我说可能增长5年以上,这个说法和文中提到的朱镕基的评价类似)。
3)考虑到明显的不确定性,我觉得不可能使用已经发表的近期数据计算中长期的健康影响。布鲁克等(2010)有关流通的研究http://circ.ahajournals.org/content/121/21/2331.是我读过的最好的研究报告。“尽管理论上的统计风险平摊到所有个体,但由暴露引起的风险升高在固定人群中的分布是不平均的,即使他们看上去是健康的,例如老年人和已经患有(不能确诊的)冠状动脉或结构性心脏疾病的人群。注意该研究也是基于美国那些目前水平低于中国很多很多倍的地区。HEI的研究http://pubs.healtheffects.org/view.php?id=349相当出色但是无疑在这个领域需要更多研究。我希望将来自己花更多时间在这个领域上。

Epidemiological studies and health risk

Thanks for your questions. Unfortunately, as you are aware there is a lot of uncertainty in terms of both the long and short terms risks from the extremely high levels of PM2.5 present in Beijing.
1) The average of the 24-hour averages of PM2.5 concentrations measured from noon to noon between Jan 10 - Oct 11 is ~102. Last year the average PM2.5 concentration was ~105 and in the first 10 months of this year it was ~99. However, the number for last year is likely a bit high (very likely no more than a couple units) because there is some data missing from the beginning of the year when concentrations were likely lower. Similarly, I believe the average concentration for this year will likely end up higher when Nov and Dec are included. Note in the US, for example, attainment of the PM2.5 standards is based on a three-year average, and then even monitors co-located in the same location will vary by up to several percent.
2) Note that I used the language "may increase". The Pope study published in the New England Journal of Medicine http://www.nejm.org/doi/full/10.1056/NEJMsa0805646#Methods was based on 51 municipal areas in the US using average PM2.5 data from the 5-year periods 1979-1983 and 1997-2001. Even in the 1979-83 time period the highest PM2.5 concentrations in the US was ~30. Therefore, some studies such as the influential Cohen et al. (which was published beforehand) http://ehs.sph.berkeley.edu/krsmith/Publications/Chapt%2017%20Urban%20outdoor%20air.pdf set the maximum city-specific concentration of PM2.5 at 50. Especially as detailed analysis has estimated that likely over 80% of Beijing is exposed to near-source traffic pollution http://www.healtheffects.org/International/Jerrett_Asia_Traffic_Exposure.pdf I reasoned that there may be some effect above these levels (in part due to nature of vehicular exhaust). Other studies have found increased life expectancy from several months to over a year per decrease in annual average PM2.5 concentration of 10ug/m3 (Finland study found decrease in life expectancy of 1.3 years from PM2.5 increase of 10). The Krewenski editorial in NEJM describing the Pope study stated a .77 year increase in life expectancy per a decrease in PM2.5 concentrations of 10ug/m3. http://www.nejm.org/doi/full/10.1056/NEJMe0809178 Therefore, I believe that a reasonable conclusion from the Pope study and other research is that life expectancy may increase be over 5 years with a decrease in PM10 concentrations of over 85ug/m3, but admittedly there is considerable uncertainty. (.77 multiplied 8.5 = 6.5, but for the reasons described above I used the phrasing may increase by over 5 years, which is similar to Zhu Rongji's comments included in the text).
3) Given the significant uncertainty, I don't believe that it possible based on research that has been published to date to calculate the health impacts from medium or short term stays. The Brook et al study (2010) in Circulation http://circ.ahajournals.org/content/121/21/2331.full is one of the better studies that I have read. "Despite theoretical statistical risks ascribed to
all individuals, this elevated risk from exposure is not equally distributed within a population. At present-day levels, PM2.5 likely poses an acute threat principally to susceptible people, even if seemingly healthy, such as the elderly and those with (unrecognized) existing coronary artery or structural heart disease." Note that this study is also based in the US where present-day levels are many, many times lower than currently found in Beijing. The HEI research http://pubs.healtheffects.org/view.php?id=349 is quite good but more research is definitely needed in this area. I hope to spend more time in the future conducting research in this area.

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