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Beijing’s hazardous blue sky

In the first analysis of US embassy “Twitter” data on pollution, Steven Q Andrews finds major failures in Chinese air quality assessments. Tighter standards are on their way, but will continue to fudge the health risks.

In the last two years, Beijing officials have announced good or even excellent air quality nearly 80% of the time, notwithstanding the persistent smog. But a monitor atop the United States embassy illuminates a different perspective: over 80% of days had unhealthy levels of pollution, and the air quality has been hazardous more often than good. Dozens of countries around the world have public air pollution reporting, but no other country describes even very low levels of pollution as excellent.

Some of the discrepancy between reported pollution levels is due to omission. The Beijing government monitors but does not report fine particulate and ozone, both of which are pollutants linked to lung disease and premature death. And some of the discrepancy is due to commission: official reports grossly understate the severity of pollution. [See Figure 1: Reporting of Equivalent Pollution Levels in Beijing, Hong Kong, Europe, and the US: Air Pollution Index Values, Pollution Levels, and Reported Color]

Figure 1.1 US monitors PM2.5 to asses pollution levels. 2 PM2.5 concentrations in Beijing have averaged over 75% (85.3%) of PM10 concentrations in the last two years based on Embassy and BJEPB city average data.

Due to public pressure arising from the US embassy assessments, the government recently announced plans to include fine particulate and ozone in public reporting, but not until 2016. In the last two years, over half the days (around 55%) in Beijing exceeded the new daily fine particulate standard (75 micrograms per cubic metre) and the annual average concentration has been approximately three times higher (around 100 micrograms per cubic metre) than the proposed standard (35 micrograms per cubic metre). [See Figure 2: Acceptable Air Quality in Beijing? (PM2.5) Percent of days meeting air quality standards based on US embassy monitoring data and US and Beijing Proposed Chinese PM2.5 Standards. Jan 2010 – Oct 2011]

But many of the misleading descriptions will remain under the new regime and, in some cases, worsen.

Figure 2.

The main publicly reported pollutant of concern in Beijing is particulate, tiny particles of solid matter suspended in the air whose impact on human health varies according to their size. Under current guidelines, so-called excellent air quality can have coarse particulate (PM 10 – meaning particulates of 10 microns or less in diameter) levels two-and-a-half times higher than the World Health Organization (WHO) guidelines. Once China begins reporting fine particulate (PM 2.5), levels three-and-a-half times higher than WHO guidelines will still be called “excellent”. PM 2.5 concentrations considered moderate in the United States will also be “excellent”. [See Figure 3: Proposed Daily PM2.5 Reporting Guidelines in China and Current US Standards]

Figure 3.

The US embassy monitor has a Twitter feed, @beijingair, which is widely viewed on mobile apps and reposted on Chinese microblogging sites like Sina Weibo. Many media reports have mentioned these hourly reports, which often assess the air to be hazardous, but this article provides the first discussion of daily average pollution concentrations measured by the embassy. These measurements are taken over the same time period as those recorded by the Beijing Environmental Protection Bureau (BJEPB).

Methodologies approved by the US Environmental Protection Agency for assessing PM 2.5 concentrations are based on a 24-hour average, so the embassy’s hourly tweets may actually overstate the severity of pollution in Beijing. For example, in the first 10 months of this year, 57 days had at least one tweet reporting “hazardous” pollution levels, although only 17 days had a 24-hour average PM 2.5 concentration that was hazardous. These days had air quality that was “very unhealthy” rather than hazardous.

According to Du Shaozhong, vice-president at the BJEPB, it is an “indisputable fact” that air pollution in Beijing has improved in recent years. In China, days that meet air quality standards are termed “blue sky days” and described as having “good” or “excellent” air quality. Officially, the number of blue sky days increased to 286 days (78%) in 2010, up from 100 days (27%) in 1998.

But, these so-called improvements are due to irregularities in the monitoring and reporting of air quality – and not to less polluted air. Most importantly, the government changed monitoring station locations twice. In 2006, it shut down the two most polluted stations and then, in 2008, began monitoring outside the city, beyond the sixth ring road, which is 15 to 20 kilometres from Beijing’s centre.

These changes continue to reap dividends for the authorities, not only in the increased numbers of blue sky days, but also in lower reported pollution concentrations. The reported number of blue sky days in 2010 would have been approximately 71 days less if the monitoring station locations had not changed. (Fifty-five days due to the 2006 changes, and 16 days due to the 2008 changes.) [See Figure 4: 16 Blue Sky Days in 2010 would have exceeded standard (Index <= 100) without 2008 additions to monitoring network. Approximately 55 additional days would have been above standard without 2006 changes to monitoring network.1] Meanwhile, though the Beijing government used to publicly report daily ozone levels, it stopped doing so in 2002.

Figure 4.1 For discussion of methods, see SQ Andrews, (2008) Inconsistencies in Air Quality Metrics: Blue Sky Days and PM10 Concentrations in Beijing, Environmental Research Letters. The 2006 changes result in a reported decrease in PM10 concentrations of approximately 12 micograms per cubic metre, (ug/m3) and the 2008 changes result in a reported decrease in PM10 concentrations of approximately 4 ug/m3. Without the changes to the monitoring network the number of Blue Sky days and annual average PM10 concentration in 2010 would have been similar to that reported eight years ago. In 2010, 286 blue sky days were officially reported and the annual average PM10 concentration was measured at 121 ug/m3. Wthout the changes to the monitoring network in 2010 there would have been approximately 215 blue sky days and an average PM10 concentration of 137 ug/m3. In 2003, there were 224 blue sky days and an average PM concnetration of 141ug/m3.

The Chinese Academy of Sciences, using its own measurements, has found that PM 2.5 concentrations actually increased by 3% to 4% every year over the past decade. PM 2.5 is believed to pose the largest health risks, because particles of this size can be absorbed into the lungs and blood.

Two weeks ago in Beijing, while very unhealthy levels of pollution were again being officially reported as good air quality, Bie Tao, an official at the Ministry of Environmental Protection (MEP) announced that public opinion would soon be used to “assess the performance of local governments on environmental protection”. Understanding the true severity of pollution and the extent to which the public and media have been misled is now increasingly important.

Data and methods

The US embassy began publicly reporting pollution concentrations and qualitative descriptions of air quality in 2008 as an unofficial resource for its staff. For this simple analysis, I downloaded archived Twitter data from January 2010 through to the end of October 2011 and compared it with data reported by BJEPB. Officially reported Air Pollution Index concentrations are converted to PM 10 concentrations and compared to the qualitative reporting systems used in Hong Kong and the European Union. Annual PM 2.5 concentrations and the ratio for PM 2.5 to PM 10 are also calculated based on daily US embassy data.

Additionally, the US embassy data is compared to the new Chinese daily and annual fine particulate standards. While there are some gaps in the data, daily concentrations were obtained on 81% of days during this 22-month period, and analysis was only conducted on the days for which there was data both from BJEPB and the US embassy. (The US embassy refused my request for the rest of the data, responding that some gaps in the data are due to maintenance of the monitor.)

Two main concerns have been raised regarding the embassy figures: that they are not representative of the city overall – an issue mentioned on the embassy’s own website – and that the data is not accurate, a position put forward by Beijing’s environmental authorities. But while the air quality at the US embassy in Chaoyang district may not be representative of all of Beijing, air quality in the area has historically been better, not worse, than the rest of the city. It is also typical in most countries to use the worst monitoring station in the entire network to calculate attainment of standards, not a selective subset as is done in Beijing. Beijing actually reported annual average pollutant concentrations for individual monitoring stations, but only in 1998, and not since.

Moreover, the monitor model used at the embassy – the BAM 2010 PM 2.5 monitor – is the only continuous particulate monitor that the US Environmental Protection Agency allows for PM 2.5 monitoring in the United States. If the data is good enough for assessing compliance with air quality standards in America, then it should be useful for at least an initial assessment of pollution levels in Beijing.

The BJEPB has argued that air quality should not be judged from data released from foreign embassies and that the measurements are hype, but the fact that PM2.5 concentrations monitored by the BJEPB are not publicly reported makes such analysis necessary. Examining daily rather than hourly concentrations helps avoid the “hype”.

Results

This research indicates that the misleading descriptions of the severity of particulate concentrations play an important role in understating the severity of pollution. The descriptions given for pollutant concentrations have a significant impact on how the severity of pollution is perceived by the public. [See Figure 5: Daily Pollution Levels and Colors in Beijing (PM10) Based on US Embassy data and Chinese, Hong Kong and European PM10 Standards. Jan 2010 – Oct 2011]

Figure 5.

Even after the proposed revisions the severity of pollution levels will continue to be understated. According to the US embassy daily reports, there was good air quality on only 3.5% of days during the year, while under the proposed reporting system there was reported good air quality on approximately 45% of days. [SeeFigure 6: Daily Pollution Levels and Colours in Beijing (PM 2.5) Based on US Embassy data and US and Proposed Chinese Standards. Jan 2010 - Oct 2011]

Figure 6.

In the last two years, Beijing reported that nearly 80% of days had good or even excellent air quality.These same levels of PM 10 pollution would have be classified as high or worse on over 80% of the days in Hong Kong and the European Union. [See Figure 7: Acceptable Air Quality in Beijing? (PM10) Percentage of days with good (China) and medium (HK and EU) air quality based on Chinese, Hong Kong, and European Union reporting. Jan 2010 - Oct 2011]. These pollution levels are quite similar to the reported air quality based on independent PM 2.5 measurements from the US embassy, where over 80% of days were found to be above American standards for safe levels of air pollution. The US EPA has also recently proposed plans to significantly tighten its PM 2.5 standard.

Figure 7.

During the past two years, PM 2.5 concentrations measured at the US Embassy were on average approximately 85% of the PM 10 concentrations reported by the BJEPB. Annual average fine particulate concentrations monitored by the US embassy have been at approximately 100 micrograms per cubic metre for the last two years.

What next?

Most people don’t really care about governmental constructs like blue sky days and pollution indices. People worry about what really matters – the impacts of pollution on their health. As the China Daily recently wrote: “All of the residents in the city are aware of the poor air quality, so it does not make sense to conceal it for fear of criticism.” Even with the proposed revisions, the severity of air pollution in China will continue to be understated.

One of the most authoritative studies on the health effects of pollution, by C Arden Pope and others, published in 2009, found a decrease of 10 micrograms per cubic metre in a city’s fine-particulate concentration was associated with an estimated increase in life expectancy of approximately 0.6 years. This indicates that if Beijing’s fine particulate concentration even reached the polluted levels of Los Angeles, life expectancy may increase by over five years. Back in 1999, Chinese premier Zhu Rongji stated his own fears that air pollution in Beijing would shorten his life "at least five years" – and fine particulate concentrations have not improved since then.

There is no reason for the Beijing government to continue to wait before publicly reporting and accurately describing the hazardous air. As a first step, the government should stop describing dangerous levels of air pollution as excellent air quality. Because fine particulate and ozone levels are already measured, they should be reported to the public. With every additional polluted blue sky day the government reports, it continues its misinformation campaign that has misled the public and helped prevent real improvements in the city’s air.

Steven Q Andrews is an environmental consultant based in Beijing. He recently completed a JD at the UCLA School of Law, and previously studied geosciences at Princeton University. His research on Chinese air pollution began while he was a Princeton-in-Asia fellow in Beijing during 2006-2007.

评论 comments

不同标准

Different standards

Standards adopted in many developing countries are not particularly strict, not on the same level as in developed countries. Firstly, these countries don't have the capacity to reduce pollution; Secondly, there's no incentive to do so, (in the sense that) the public, being deceived by official data, normally don't pressure to do otherwise. Therefore, the civil society is playing a considerably important role in pushing for government's action.

sqandrews
21:5211.12.2011

谢谢，bingo

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.

meleze
16:2906.12.2011

2008奥运和2012奥运

Olympic games of 2008 and 2012

Why don't you tell any story on the efforts done by the Beijing city during the week of the Olympic games? Those efforts have been cancelled in the following years. It has been a lie that China awarded by the olympic games would be more conscious of the pollution it is generating and more flexible in the worldly talks around Kyoto.

Designed to Whitewash

I do not believe the new standards, when applied to Beijing air quality measurements, will prompt action to clean up the pollution. The bottom line is that the economic action causing the pollution is deemed more important than the citizens' safety.

Cleaning up is seen as an economic drag and not something positive, important, and necessary. This autumn's smog has indeed been bad, and was noticed by a pilot who posted these photos, taken in November:
http://www.ab9il.net/avgallery/china-smog.html

Converting to cleaner fuels, cleaner heating, and greener manufacturing is a good thing! China could lead with pride if the bosses had a different opinion. The people deserve better than today's situation.

The author does not appear to be a real expert, and I have suspicions that he is simply an alarmist

There are many common-sense errors:
1. Previously, air quality standards have always been drafted on the basis of the level of development and the real situation in each country. As a result, the WHO has given guidance indices for different stages of development, and each country can draft their own air quality standards based on the aims they can achieve.

2. Research in many countries has shown that the proportional relationship between PM2.5 and PM10 is around 50%, so the WHO has defined the value of PM2.5 as half of PM10 when drawing up air quality guidance indices. Has has the author done research on his own?

I don't know how the author researched air pollution in China- has he carried out his own tests? That data has been obtained by himself? Information with no basis can't be used to draw conclusions.

gooodming
19:1008.12.2011

认识什么是主观和客观

标准是人制定的，但是空气污染及其危害是客观存在的。不管你用什么标准，污染和危害都会在那里。

就算是发展中国家和发达国家标准不同，但是污染的危害会不同吗？发展中国家会因为自己的发展程度而获得更小的污染危害吗?

所以那什么发展程度不同，标准不同的人需要想想标准是干什么用的。

Learn the difference between objective and subjective

Standards are drawn up by people, but the existence of pollution and the harm it causes can be shown to exist objectively. No matter what standards you use, the pollution and harm are still there.

Even if the standards in developing countries and developed countries are different, does that mean the harm caused by pollution is any different? Do developing countries sustain less harm from pollution as a result of their level of development?

So people who think that standards should be different for countries in different levels of development need to think what these standards are used for.

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.

rstcyrmd
04:2208.12.2011

出色的研究

Outstanding research

Steven, congratulations on providing such a thorough examination of the data. I have been pushing this issue on my blog for years and promoting the US Embassy's feed, but I've always hoped someone would actually crunch the numbers for true comparisons. This is by far the most researched piece I've seen on this issue, and I am already forwarding it to others as a must-read.

Clarify the data?

Steven, I'm hoping you can clarify some points:

1. Can you be more specific as to your claim that US Embassy's average PM2.5 is 100 ug/m3 for the last 2 years? What's the exact number for each year? And how did you tally this data -- I assume you simply took the 24-hour Twitter results from each noontime and averaged it?

2. This issue of mortality is always a huge question my patients always ask me in clinic here in Beijing. You state "life expectancy may increase over 5 years" compared to LA. Can you please clarify: in Pope's study, how many years had he been tracking people, in other words was this 5-year effect noted after 20 years of data, 8 years, etc? And how did you calculate this effect? Don't forget that even Pope mentions that lung cancer effect is linear, but cardiovascular effect is NON-linear and flattens out. Can you walk us through the math you did?

3. And on a similar note, these mortality estimates are "long-term". Can you extrapolate this data to medium or short-term stays? So if someone lives in Beijing for a year-year post, what is their increased mortality risk? If you don't know, what's the best data you've seen on this?

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.

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.

need help for AQI data of Beijing

Hi, Vance
Our studio recently released an app -- "北京空气污染指数"(http://itunes.apple.com/cn/app/id477700080?mt=8), it is warmly welcome by many citizens.
Now we plan to update it with some historical statistics function, but we could find more earlier data before 2011-7-28 on twitter @BeijingAir or any place else.

US Embassy's PM2,5 measurements

It is very suprising. I've been engaged into the technology and reseaches on air quality for 41 years, on the day of the very beginning of the second ten years of 21 century, I felt uncomfortable as I read a report by Steven Q Andrews, who seems to know the giant city's air pollution well just with a glimpse.

However, the very first problem came to the self-appointed expert is：whether we can guarantee the device atop the US ambessary is qualified as required in terms of accuracy and whether we can secure the statistics and graphs be true against reasonable doubts and deliberations, which is, in priority, taken into account in air quality monitoring and which is prevaricated by Mr. Andrews as the monitor "is the only continuous particulate monitor that the US Environmental Protection Agency allows for PM 2.5 monitoring in the United States". I don't intend to be involved in the internal business of USA Environmental Protection Agency, who take charge of the business of authentication. What I want to say, only in my own opinion, is the authentication is not absolute, but for the sake of effectiveness of the statistics, the devices have to be in compliance with certain specifications. It is my concern that the specifications do not deserve the respect as it should in Beijing.

All the heavily-pulluted phenomenon of air quality in the states-quo Beijing generate under the condition of heavy fog. Currently, the monitoring survey on particulate matters adopting particuleβabsorptiometry is highly sensitive to water melocules, becuase hydrogen accounts for part of a melocule as around 10% in terms of quality. The higer Z(atomic number)/M(melocular weight) (the value of Z/M of hydrogen is 1, while that of common chemical elements is 0.5) of hydrogen in water melocule the higer absorbing rate of particuleβ. This means the value of PM2.5 would increse substantially to be higher than the actual one once the moisture in the particulates detected was not deprived in the entrance of the sampler.

Obviously, the monitor supplier offers the attached de-moisturation unit but without the information on various efficiencies in different environments. Take Beijing for example, the physical features of the particulate matters are almost unique. All in all, I'm strongly doubting the PM2.5 detected by the monitor atop the US ambessy involve large quantity of water mist. Yet, I won't reconsider my stand point of view until I am given the real evidence that the water mist is deprived efficiently during the survey.

Final but not least, do not quote the authentication of USA Environmental Protection Agency and the specifications by it. As known to all, the hundreds of thousands of a model of PM10 monitor approved by the agency been sold in Europe (in US as well, of course) have been proven to be featured with losing particulate matters in large quantity, sometimes the losing is over 50%. Few people were aware of this defect. The manufacturer tried to addressing this problem by adding a extra unit onto the monitor after the exposure of the defect. This episode helps many understand it is not a walk in the garden to do monitoring survey on air pollution either a piece of cake to resolve issues as they occur. As well, this interprets the US fellows would make mistakes sometimes.

Finally, I believe the lessons acquried by the USA on environment monitoring survey are of great meaningful. We have to be aware of the positive aspect of this great nation on the development of techniques, science and technology. Yet, some on behalf of this nation should follow the least spirit of modesty while some events undertaking in some nations are not so "great".

Maybe I would not issue my discussion on the rest of the text until Mr. Andrews got rid of the moisture embracing the monitor and gained the density statistics.

PM2.5 increased according to government

You raise legitimate concerns over the accuracy of the PM2.5 monitor atop the US embassy, but I think you are too focused on this issue and have missed the larger point of the article. Please note that in the article I state that this is an "initial assessment."

In terms of doing more specific analysis regarding moisture levels affecting the accuracy of the monitor and density statistics, I agree that this would be beneficial but I do not think it is necessary for the general analysis done and conclusions reached. Please note that the US Embassy refused my request for data. In response, I submitted a Freedom of Information Act request to the State Department for the data as well, but I am still waiting for a response and so the analysis you propose is not feasible at this time.

As I mention in the article researchers at the Chinese Academy of Science have been quoted as saying the PM2.5 concentrations in Beijing had been increasing by 3 to 4 percent over the past decade. Recently, the government has changed its mind and said the PM2.5 concentrations have decreased in recent years, but the average PM2.5 concentration calculated from the US Embassy monitor over the past two years of 100ug/m3 is consistent with peer reviewed studies of PM.5 concentrations in Beijing published to date. Furthermore, as I mention in the article, air quality in the area around the US embassy has historically been better, not worse, than the rest of the city

Furthermore, while you raise issues with the US embassy monitor, many people have raised similar concerns regarding the accuracy and reliability of Chinese PM10 monitoring data as well. I would have preferred to use Chinese government PM2.5 data, but as I mention in the article the fact that PM2.5 concentrations monitored by the BJEPB are not publicly reported makes the type of analysis that was done necessary.

If you have access to a better data set of daily PM2.5 concentrations over the past two years in Beijing please do let me know.

China Air Quality

This is good insight into the current situation into China. As they push forward into the PM 2.5 standard there will be greater visibility into the extent of the problems that they face. With the TEOM it has been found worldwide that the technology undermeasures. There has just been advancements in technology that allow for greater accuracy in the readings and many of the networks measuring for PM 10 were put in quite a few years ago.

However it is a good step forward in the right direction and awareness brings solutions on how to combat the problem.

I would like to point out that Mr. Ivo Allegrini is a manufacturer of Air Quality monitoring equipment.

[This comment has been moderated. Please remember to avoid ad hominem assertions and keep the arguments about the facts, not the people involved]