xinhua's international herald leader on the us embassy air quality monitor

This post contains some translation and commentary on the recent story in Xinhua's International Herald Leader (国际先驱导报) on the US Embassy's independent air quality monitor. The story was reprinted in the Hong Kong-based Phoenix magazine (凤凰) here.

First, title: I think it's noteworthy that, although the stories in the two Chinese-language sources are the same, the title in the IHL is 美国驻华使馆自建空气监测站 ("US Embassy Independently Sets Up Air Quality Monitoring Station"), whereas that in the Hong Kong-based Phoenix is more provocative: 美驻华使馆发布自测北京空气指数 与气象局数据分歧 ("US Embassy in China Issues Independently-Tested Beijing Air Quality Index - Different from the Meteorological Bureau's Data").

And now content: The IHT begins with similar content as the China Daily story: information about the Embassy's twitter feed and concerns about discrepancies with the officially-reported data, followed by assurance from an Embassy official that the numbers are not directly comparable. As in the China Daily, the IHT story then describes the health impact differences between PM2.5 and PM10.

Following this, though, the IHT diverges from the China Daily story. A section titled 建监测站应循通行规则 (Regulations Should Be Followed When Setting Up Monitoring Stations) questions whether the US Embassy's data is even valid:

中国气象科学院院长张人禾向《国际先驱导报》介绍道，设立空气监测的站点需要在整个区域具备代表性，且50米内不能有污染源，否则将严重影响监测结果。...

因此事实上，美国驻华使馆自建的空气监测站并不符合通行的国际规范。

According to Zhang Renhe, Director of the Chinese Academy of Meteorological Sciences, an air quality monitor must be installed in a location representative of of the entire city; moreover, there should be no pollution sources within 50m that could strongly impact the monitoring results...

In fact, the US embassy's independent air quality monitoring station is not in accordance with international criteria.

于去年8月建成的美国新使馆区坐落在北京CBD商业圈、背靠亮马河的黄金地段，它毗邻女人街等商业场所，平日里交通繁忙、人群熙攘，这些因素都很可能对监测站的数据收录产生影响。

记者28日在美国使馆的所在地更是发现，其对面原有的星吧路酒吧餐饮街已被大规模拆除，工地上一片狼藉，灰尘扑面。而它南面的其他使馆区仍在建设中...

Completed last August, the US Embassy is located in the CBD business area, near the prime locations around Liangmahe. It is near the Ladies' Market and other commercial areas with high weekday traffic and bustling crowds; these factors all possibly influence the data recorded by the monitor.

On the 28th, this reporter visited the location of the US Embassy and discovered the large scale demolition of Super Bar Street across the street; much dust blew out from the messy construction site. Additionally, on the south side was another embassy area under construction...

Although the article does not question the accuracy of the Embassy's data, it clearly indicates that the Embassy's data is disproportionately bad because of poor and non-standard monitor placement. This possibility was not raised in the China Daily piece.

(Side note for future investigation: I think perhaps the US Embassy monitor is at the old embassy near Ritan park, not on site at the new location.)

Moving on, the article briefly mentions Steven Andrews' criticisms of Beijing's air quality management, that Beijing's air quality monitors have been selectively placed in areas of low pollution to yield better overall averages and that officials artificially inflated the statistics on number of blue sky days. Although it is noteworthy that the article mentions Mr. Andrews at all (I haven't seen his analysis directly covered in the Chinese media before), the article immediately quotes experts supposedly refuting his claims:

“蓝天数量有目共睹，如何造假？”周凌唏评价到。在她眼中，为了北京奥运会顺利召开，在北京民众的努力下，的确明显提高了首都空气质量，“蓝天多，说明大气透明情况好，在一定程度上说明内含的污染物就少。”

而张人禾对“监测站多分布在低污染区”的质疑感到“不解”，“别忘了，空气也是流动的。”他说。

"Everyone can see the number of blue sky days, so how can they be faked?" [an analyst with the Chinese Academy of Meteorology] commented. In her eyes, to ensure a smooth Olympics in Beijing, through the effort of all of Beijing's citizens, there was indeed an obvious improvement to Beijing's air quality. "More blue sky days means a more transparent atmosphere, which means to some extent less pollutants."

In addition, Zhang Renhe felt he "couldn't understand" the suspicion that "some of the monitoring stations are located in low pollution areas." "Don't forget, air is also flowing," he said.

I can't quite understand what either of these experts meant, which may or may not be due to the language barrier. Despite that, though, it doesn't seem as if either expert addressed Mr. Andrews' concerns directly, so it doesn't make sense to me that the article would raise them at all.

Finally, the article quotes an anonymous Beijing EPB official saying that the Embassy is breaking no laws by independently monitoring air quality, before closing with this quote:

“不过，与此相关的我国《环境监测条例》已被纳入国务院今年的立法计划中，有望今年内通过。”他说。

"However, the relevant "Environmental Monitoring Regulations" have already been placed into the State Council's legislation plan for this year; there is hope they will be passed this year," [the Beijing EPB official] said.

In other words, although there is nothing wrong with Beijing's current monitoring system, the Beijing EPB still hopes that it will be improved this year with new, unspecified State Council legislation.

Although I was initially encouraged by yesterday's direct and somewhat challenging China Daily piece, this Chinese-language Xinhua piece is more of what I would expect from China's state media: convoluted logic and fact-twisting that attempts to shape reality to fit the government's agenda as opposed to strong investigative reporting attempting to uncover the truth.

china daily features online survey on beijing's air quality monitoring

When I wrote yesterday about the China Daily article on the discrepancies between China's officially reported air quality data and the US Embassy's BeijingAir Twitter feed, I didn't realize that the China Daily story appeared on the site's home page along with an incredibly direct web survey:

Web surveys are, of course, not scientific or reliable at all, but nonetheless here's a screen capture of the results as of around 11am this morning:

It's difficult to imagine such a critical survey happening on a Chinese-language state media site, but I will keep an eye out for anything comparable.

Lastly, for the record, there are several mistakes in the China Daily story that I should point out. Three are in this sentence alone: "A blue-sky day is when the city's air pollution index, the level of five airborne pollutants, falls below 100, indicating that no health implications exist."

First, MEP makes no claim that blue-sky days have "no health implications," only that those days have the poorly-defined "excellent" or "good" air quality. Air quality on blue-sky days can certainly have negative health implications, especially for sensitive populations in the short term and for everyone in the long term. What MEP calls "good," the US EPA calls "moderate," saying, "Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution."

Second, the air pollution index only covers three pollutants, not five. I'm not sure how China Daily made this mistake, because later in the article they describe the number correctly ("the current evaluation system uses only three indices: Sulfur dioxide, carbon dioxide and PM 10s"), although they get the pollutants wrong. (The three are sulfur dioxide, nitrogen dioxide, and PM10.)

Third, this is minor, but a blue-sky day is a day in which the API is technically 100 or below, not below 100.

china daily questions official air quality statistics

The story about the US Embassy's BeijingAir air quality twitter feed (whose subscribers now top 2,200) was picked up by the China Daily today. Perhaps surprisingly, the China Daily article uses the embassy data to question whether the Beijing EPB's official data present an accurate view of Beijing's air quality:

China Daily calculated that only five days were above "moderate" level in May on BeijingAir, but the local environment bureau said on its website on May 31 that the capital's air quality was the clearest during the same period since 2000, with 25 blue-sky days.

However, the article goes on to quote both an embassy official and a Chinese expert cautioning that the single station is not representative of Beijing's overall air quality:

"This is a single site," [US Embassy spokesperson Susan] Stevenson said. "It cannot be used to measure the air quality across the city. They can't be compared."
...
"The embassy is located in the central business district, which has heavy traffic, and its monitoring station cannot represent the overall picture," Zhu Tong, an environment professor with Peking University, said yesterday.

Signficantly, the China Daily article does not question whether or not the embassy data is valid for that area, only whether the single data point can be extrapolated out to the rest of the city. To me, this is an important distinction, because collective agreement that the embassy data is valid should ultimately help pressure the Beijing EPB to set up their own real-time PM2.5 monitors across the city (which is the direction we should be driving in).

The article closes with this comment, noteworthy for its open questioning of air quality data. Such questioning is rare in the Chinese state-run media:

Some residents expressed doubts about the official air quality data.

Wang Haiyan, a 36-year-old Beijinger living in Chaoyang district, said that even under a different measuring system, there is still no reason to get such different air quality results.

Within Chinese-language media, Xinhua's International Herald Leader (国际先驱导报) published a story two days ago (also printed with a different title in the Hong Kong-based Phoenix magazine (凤凰) here) on the US Embassy's air quality reporting; the story included this photo that is apparently of the monitor:


As one would expect, the tone of the Xinhua piece is much more defensive of the official data and critical of the embassy. Unfortunately, I don't have time now to write more on this; stay tuned tomorrow for some translation and commentary.

beijing epb responds to us embassy air quality twitter feed

A friend tipped me to an article in today's South China Morning Post (registration required) on the US Embassy's Beijing air quality twitter feed.

Although the majority of the content of the SCMP piece echoes that published last week in other sources, there is one important bit of new information:

Du Shaozhong, deputy director of Beijing's environment protection bureau, was unaware of the US embassy's move, but said: "Any attempts to question our figures with a single monitoring station are not authoritative enough."

This could get bad. Let's see if it gets picked up by other media and begins to escalate.

FYI, the twitter feed has around 1600 followers now (up from 300 just a week ago).

us embassy outed as source of beijingair twitter feed

On Friday of last week, Time's Austin Ramzy outed the BeijingAir twitter feed as being set up and administered by the US Embassy:

The U.S. Embassy operates a single station in eastern Beijing that records levels of PM2.5, fine particles considered particularly dangerous to human health...

While the U.S. doesn't actively promote the information, it has slowly been getting more attention from Beijing residents concerned about the city's air quality. "The U.S. Embassy has an air quality monitor to measure PM 2.5 particulates on the Embassy compound as an indication of air quality," says Susan Stevenson, a State Department spokesperson. "This monitor is a resource for the health of the Embassy community." She cautions that citywide analyses cannot be done from a single machine, but because the embassy has the data available, it makes it available to others.

Before the story came out, there were around 300 followers of the feed; now there are more than 1,100 and rising fast.

Beijing experienced some bizarre and extremely rapid changes in air quality on Thursday and Friday of last week. On both days, BeijingAir reported maximum pollution levels (hazardous air, AQI = 500) for brief periods in the afternoon. However, hazardous air was never reported by either the Beijing EPB or MEP, presumably because the pollution spikes on both days were short-lived enough that the overall 24-hour averages evened out as just "light pollution." (More discussion here and here.)

Here's a graph showing BeijingAir and MEP-reported air quality over the period noon Tuesday to midnight Sunday last week. Because MEP has no system for real-time reporting, the extreme pollution spikes on the 18th and 19th were never truly reflected in MEP's air quality data:


The events of last week highlight the need for real-time reporting of air quality in Beijing. I wonder if the growing popularity of the embassy's twitter feed will ratchet up pressure on MEP / Beijing EPB to implement such a system here in Beijing.

Final note: the speed of the drop in pollution levels during the afternoon of 6/19 was stunning. With no technical background in air quality modeling or meteorology, I have no idea how this is even possible:

more info on beijing's 6/18 air quality

Yesterday, beginning at around 10am, there was a sudden and dramatic spike of air pollution here in Beijing. I blogged about it here, and it was covered in the Guardian and Time's blog, with surely more to come. The pollution spike lasted until close to midnight yesterday. I presume yesterday evening's rain is what ended the event, although it should be noted that, as I write this, the pollution seems to be creeping up again.

Yesterday's pollution spike may be seen very clearly in the BeijingAir tweeted hourly data over the past couple of days. Shown here are PM2.5 concentration and AQI:


Note the missing data points in the afternoon of 6/18 and the maxing out of AQI at 500 during the same period.

Despite yesterday afternoon's stifling pollution, MEP's officially reported Air Pollution Index (API) for 6/18 was just 104 - indicating "slightly polluted" air quality. The reason, as noted yesterday, is that MEP's API does not report real-time air quality; it is an average air quality indicator covering noon to noon beginning from the previous day. Therefore, we wouldn't expect the afternoon pollution spike of 6/18 to show up until the 6/19 reported data point.

However, the API for 6/19, which was released a few minutes ago, is just 159 ("lightly polluted"), which is significantly lower than I would have expected.

--
Edit: An API of 159 - corresponding to a PM10 concentration of 266 ug/m^3 - still represents awful air quality, despite my use of the word "just." China's daily/yearly goals for PM10 are 150/100 ug/m^3, while the WHO's recommended targets are 50/20 ug/m^3.
--

The following graph shows MEP PM10 and API data, as well as BeijingAir PM2.5 and AQI data, for the last few days. Note that the absolute magnitudes of the BeijingAir and MEP data are not directly comparable due to slightly different measurements and scales. But the trending should be the same:


Although the MEP data increases beginning noon on 6/18, as one would expect, the increase just doesn't seem commensurate with the seemingly atrocious pollution yesterday afternoon and evening.

What's going on here? Well, there are a few options, but I'm not sure which one is correct:

First - it's theoretically possible that, because MEP averages over 24 hours over a number of different monitoring stations, the overnight reduction combined with lower pollution outside the city center brought the overall average down. Here is the daily individual monitor data from the Beijing EPB:

There are certainly some high readings, e.g. Dongsi, but there are also some that report only half as bad (Pinggu, Miyun).

Second - it is possible that the BeijingAir monitor is either not calibrated correctly or suffered some unusual activity (e.g. a car idling for an extended period outside the monitor). This seems unlikely.

Third - I'm not sure if this is correct or not, but it may be possible that the pollution event was largely PM2.5 - particles of diameter smaller than 2.5 microns - that do not register in the EPB's monitoring stations designed to measure PM10. Can anyone comment on this?

Fourth - I don't think I need to write this option explicitly.

More info as I learn it.

air in beijing hazardous

BeijingAir is currently reporting hazardous air quality in Beijing (there was an error in the most recent hour, but you can see the PM2.5 concentration slowly creeping up over the course of the morning and early afternoon):


Note, though, that with the AQI maxed out at 500, the air quality is theoretically worse than "hazardous," whatever that might be.

On the other hand, MEP is reporting an API today of 104, "slightly polluted."

A few people have asked me about this blatant discrepancy, so here's a brief comment:

It's important to remember that MEP's reported API for 6/18/09 is actually an average API for the period noon to noon 6/17 to 6/18. Given that this current pollution spike seems to have rolled in over the course of the late morning and early afternoon, it is reasonable that the impact has not yet registered in the MEP reported data. From the perspective of MEP's official reporting, we will have to wait until around 2pm tomorrow to see the results of this episode.

Of course, this discrepancy highlights the necessity of working towards a system of real-time air quality reporting (like the AIRNow program in the US) in Chinese cities. (More on this in another post.)

Final note: during my time in Beijing (3.5 years), I've only experienced a handful of days in which MEP reported a 500 API. The most recent ones were 12/28/2007 and 12/12/2006, plus a few during the sandstorm season of the spring of 2006. I am curious to know if tomorrow will yield another.

how clean were april and may?

This past spring, the months of April and May in Beijing were reported as the cleanest April / May in a decade. (Sources for April: China Daily and Beijing EPB, see also my previous post; sources for May: Xinhua and Beijing EPB.)

Independent of the quantitative results, these reports seem to confirm what a lot of people have been mentioning to me, that this past spring has seemed surprisingly clean.

Let's evaluate the truth in all of this. The following graph shows average API*, average PM10 concentration, and number of Blue Sky Days for the period April-May from 2005 through 2009:

From these numbers, the results are pretty clear: the period April-May 2009 in Beijing was indeed significantly better in terms of air quality than the same period in any of the previous four years. (I could have looked farther back, but I decided only to look at five years total for this analysis.)

Here are some comparisons of 2009 vs 2005-2008 averages:

I think it's probably fair to say that the air quality this April and May was 30-40% better than the average air quality during the same period over the previous four years.

As usual, we should celebrate the progress while being mindful of the significant improvements still required. My calculated average PM10 concentration for this period, 117 ug/m^3, is still well above China's annual target (100 ug/m^3) and well well above the WHO's ideal target for developed nations (20 ug/m^3). It is also well above my estimate for the average PM10 concentration during last year's two-month Olympic period (79 ug/m^3).

Related:
Summary of Beijing's 2009 first quarter air quality
Summary of Beijing's 2008 air quality
Update on fall air quality in Beijing

*I don't really like averaging API, because it can lead to some misleading results (further discussion in this post), but despite that I still think it has value as an indicator here.

news to be positive about: PM2.5 and ozone monitoring coming soon; Pollution Transparency Index

Three recent air pollution-related news stories to be positive about:

1) China Daily: Tougher rules for air quality likely soon

China is mulling more stringent appraisal standards for air quality, and pilot projects are likely to start from coastal cities in the Yangtze River delta and Pearl River delta next year.

The environmental authorities are planning to include particles less than 2.5 microns (PM2.5) and ozone, into the Air Pollution Index (API), which currently measures the concentration of sulfur dioxide, nitrogen dioxide and PM10, or particles smaller than 10 microns.

This is terrific news. With the pressure of the Olympics off, I was beginning to think that MEP had forgotten about the comments they made last year on this topic. No dates given in the article, but still a positive sign.

2) China Daily: Pollution index up and running

China's first Pollution Information Transparency Index (PITI) has been officially launched and has published its first annual assessment of the pollution information disclosure performance of 113 Chinese cities for 2008.

The PITI, set up by the Institute of Public and Environmental Affairs (IPE) and the US-based Natural Resources Defense Council (NRDC), is part of efforts to strengthen public awareness and supervision of environmental issues and protection.

Here is the link to the index methodology and results (Chinese). Note that the index encompasses several types of pollution, not just air pollution. Although most cities scored rather poorly (Beijing overall scored 49.1 out of 100), it's still encouraging to see this index go public as a baseline for future comparison. It is also very encouraging to see this activity by NGOs reported in the Chinese media.

3) Xinhua: China's central environment authorities to open hotline for direct complaints

BEIJING, June 4 (Xinhua) -- People who have complaints about environmental pollution in China would have a direct way to inform the Ministry of Environmental Protection as the ministry opens a tip-off hotline on Friday, the International Environment Day.

The ministry said Thursday that the hotline, 010-12369, will take calls about emergency environment issues, cross-provincial pollution and other environmental issues that should be directly dealt with by the ministry.

A nice little green hop, I'd say (to borrow an expression from the Green Leap Forward).

new report shows widespread air quality data manipulation

Last fall, I wrote about Steven Andrews' report demonstrating data biasing in Beijing's air quality reporting.

The China Environment Forum has just published a second peer-reviewed report written by Mr. Andrews, this one detailing on a much larger scale the data manipulation present in air quality reporting across all of China. Mr. Andrews' overall conclusion is as follows:

Publicizing the API and where cities rank in terms of air quality keeps the public informed of air quality and potential health threats. However, misleading data presentation and revised laws have prevented the API system from accurately communicating air quality problems to the public.

Mr. Andrews' report focuses on several points, including:

1) SEPA's loosening of ambient air quality standards in 2000 artificially inflated the number of cities in compliance:

In 2006, the annual average NO2 concentration in Beijing was 66μg/m3 and in Guangzhou it was 67μg/m3 (BJEPB, 2007; GZEPB, 2007). Under the 1996 standards, Beijing and Guangzhou would have exceeded the annual average NO2 standard in 2006 by 65 percent and 67 percent, respectively. Under the revised standards, both were in compliance (SEPA, 2000).

(Note: link to old standards here; link to new standards here; discussion and comparison to international standards here.)

2) The assignment of 100 as the cut-off point for a "Blue Sky Day," coupled with rising pressure for cities to meet increasing numbers of annual Blue Sky Days, has encouraged the "bumping" of API data just above 100 to just below. Mr. Andrews writes:

Although the establishment of “Blue Sky” targets and well-publicized tallies of the number of days meeting the national standard has resulted in an easily understood metric for air quality, it strongly appears that pollution levels near this boundary are being manipulated in many major cities.

This was one of his core findings in his previous report on Beijing alone. In this report, Mr. Andrews expands the analysis to many more Chinese cities. The table below shows 30 cities which reported above 90% of all API values within the range 96-105 as 100 or below in a given year. (Statistically, one would expect around 50% of data points in this range to be on either side of 100.)3) The moving of monitoring stations within cities has artificially inflated air quality:

Although there has been a reported 10.8 percent decrease in Beijing’s annual average NO2 level between 1998 and 2006, the two stations in traffic areas have reported annual average NOx concentrations 100 percent higher than the non-traffic stations (BJEPB, 1998). This indicates that all the reported decrease in NO2 concentrations in Beijing from 1998-2006 may be due to the changing locations of monitoring stations.

4) Although not one of Mr. Andrews' key conclusions, one of his smaller but fascinating findings is that, apparently, there was a mistake in the English-language version of MEP's website regarding how to calculate API. This is something I never realized, but has apparently wreaked some havoc in international data analyses of air quality in China:

Although the calculation methodologies to go from API values to pollutant concentrations are straightforward, an error in the sample calculation on the MEP website has lead to misunderstandings of the true severity of pollution levels—inaccuracies that have been replicated in several leading reports on air pollution in China.

It seems that MEP has since removed the English explanation of API calculation, so I'm not sure what this error was; I'll keep digging and see if I can find out more.

Thoughts

Similar to Mr. Andrews' September 2008 report, this report is a scathing indictment and well-supported criticism of MEP's air quality data quality and transparency. It highlights a number of issues that MEP - as well as city and provincial-level EPBs - should ideally work quickly to resolve in order to regain international trust and credibility.

april 2009 was beijing's cleanest april in 10 years

I'm a couple of weeks late on this (still playing catch up), but I thought this recent story was worth noting.

On May 2nd, China Daily reported that "Beijing has 'cleanest month' in 9 years," writing, "the city experienced its best month of air quality since 2000 with 23 blue-sky days in April."

The excellent blog Daily Dose of Air Pollution highlighted that this claim is dubious, noting at least three other months (August and September, 2008, and August 2006) in which Beijing had higher numbers of Blue Sky Days and lower average APIs than April 2009.

I think I've identified the source of confusion. The official Beijing EPB announcement (Chinese), titled 4月本市空气质量创2000年以来同期最好水平, states specifically that April 2009 was the best April since 2000, not the best month overall. It seems the China Daily (or the Beijing EPB spokesperson during the press conference) misrepresented the real announcement.

Two follow up points:

1) While acknowledging progress, we should also simultaneously not get too excited over the "clean" air. The Beijing EPB claims that the average PM concentration during this month was 120 ug/m3 (主要污染物可吸入颗粒物月均浓度为每立方米0.12 毫克), which is still well above China's national air quality target (100 ug/m3) and six times higher than the WHO recommended guideline (20 ug/m3). (Comparison of international standards in this post.) Although it is critically important in China to note progress, we must not wrap ourselves so much in cheers of success that we become blinded to the significant challenges and work still ahead.

2) The China Daily article describes in more detail than I have ever seen how the economic slowdown may have contributed to improved air quality, writing:

Besides strict environmental protection measures, experts think the global economic slowdown might be playing a positive role in environmental protection.

Zhu Tong, an environment professor with Peking University, told China Daily on Friday that heavy industry has decreased production in many polluting factories, which benefits the air.

"Most companies in heavy industry are seeing fewer orders. The output of the Shougang Group this year so far equals the same period during the Olympics," said Wang Dawei, head of the air quality control division of the Beijing municipal environmental protection bureau.

In the first season this year, the added value for ferrous metal and chemistry manufacturing in the capital was 3.36 billion yuan ($490 million) and 1.85 billion yuan, a year-on-year decrease of 18.1 percent and 17.9 percent respectively.

If the improved air quality is indeed due to the slowdown, then this means there is even less cause for celebration.

slides from my talk wednesday night

The other night I had a great time presenting at the Beijing Energy Network's wonderfully titled BEER (Beijing Energy & Environment Roundtable) event. The title of my talk was "150 Million and Counting... Controlling the Energy and Environmental Impacts of China's Vehicles." I tried to have fun with it - I presented it at 9pm at a bar, after all - while touching on a range of topics and issues related to the transportation sector in China.

Although I fear the slides may seem a little too bare-bones without the context of my accompanying speech, I did get enough requests to distribute that I figured I might as well put them online:

I welcome any questions or comments either here or by e-mail at livefrombeijing at gmail dot com.

Lastly, apologies for the light posting recently; I have been slammed at work in preparation for a trip to the States this weekend. I'll be gone for two weeks and will post while there if time permits, but no promises...

summary of beijing's 2009 first quarter air quality

Yesterday, Xinhua reported that Beijing achieved above an 80% "blue sky" rate in the first half of this year:

BEIJING, March 31 (Xinhua) -- Beijing saw 73 "blue sky days", 81.1 percent of the total, in the first three months of 2009, Beijing authorities said here on Tuesday.

The city experienced six more blue sky days than in the first quarter of last year, and 24.3 days more than the average of the last decade, said an official of the Beijing Municipal Environmental Protection Bureau.

Experts at the bureau said active cold airflows had helped particulate matter to disperse.

Efforts to reduce pollution from heating systems had paid off with January having the most blue sky days since 2000, said the official.

For those who prefer original sources, here is the notice from the Beijing EPB (in Chinese).

Let's take a closer look at the data and examine what this means in terms of air quality.

First of all, as a quick introduction for new readers, China defines "Blue Sky Days" as days for which the Air Pollution Index (API) is 100 or below. For a detailed description of exactly what the API is, see this post. Past Beijing API data may be queried from MEP's datacenter, but unfortunately only in Chinese.

For this post, I queried the data for 1/1/09 to 3/31/09, and ran some quick analyses to see what interesting things I could find.

Part 1: Checking Beijing's EPB's Numbers

The Beijing EPB claims "截至3月31日，今年累计73个达标天，占监测天数的81.1%。其中一级7天，二级66天，三级15天，四级1天，五级1天。" The second sentence says that in this time period there were 7 days of Grade 1 (API 0-50) air, 66 days of Grade 2 (API 51-100) air, 15 days of Grade 3 (API 101-200) air, and 1 day each at Grade 4 (API 201-300) and Grade 5 (API 301+).

However, by my count, there were 8 days of Grade 1 (one more than reported) 64 days of Grade 2 (two less than reported), then 15, 1, and 1 days of Grades 3, 4, and 5, respectively (identical to that reported). It seems pretty basic to me that you would want your publicly reported data summary to match your public database, so I can't imagine what's going on here. This is especially true because, in this case, the data indicates Beijing did better than they claimed.

The data for one day, 2/19/09, is missing from the database. If we assume that 2/19 was a Blue Sky Day, though, then at least we do indeed have 73 Blue Sky Days for the quarter.

Part 2: Converting to Pollutant Concentrations

Because API is a unitless index, in order to evaluate air quality we have to convert back to pollutant concentrations. This is a bit tricky, because the API is only reported according to whichever pollutant had the highest daily concentration, meaning that we do not have daily raw data for every pollutant. Still, we can make a rough approximation by assuming that PM10 is the limiting pollutant on all days. (Of the 89 data points, 72 (81%) were reported with PM10 highest, 9 were reported with SO2 highest, while 8 had no pollutant data because no pollutants are listed for Grade 1 air quality days.)

In any case, given the above assumption, this graph shows calculated daily PM10 concentrations for this quarter:


These data yield a quarterly average PM10 concentration of 124 ug/m^3. This is very similar to what I calculated as last year's annual average.

124 ug/m^3 is still well above China's annual target (100 ug/m^3) and well well above the WHO's ideal target for developed nations (20 ug/m^3).

Appendix

For those of you following along at home, here is an Excel formula for converting API to PM10 concentration (in this example, the API would be in cell E9):

=IF(E9<51,e9,if(e9<201,(e9-25)/0.5,if(e9<301,(e9+300)/1.429,if(e9<401,(e9+225)/1.25,e9+100))))

This is based on equations presented at the bottom of this post.

3-21-09 api missing

I'm not sure why, but Saturday's API was never reported.

In 2008, there were two days for which the API was not reported. There were no missing days in either 2007 or 2006.

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Update 3/31/09: The API for 3/21 has been added to the database.
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greenpeace china beijing api widget

Greenpeace China has generated a cool new Beijing API website widget that supposedly updates automatically every day:

Looks good!

For a general introduction of API, see this post.

dust storm blowing into beijing?

Stay inside today; Beijing's API currently stands at 268 (PM10 concentration 397 ug/m^3). This is considered Very Unhealthy. (More info here.)

I thought this was a dust storm blowing into Beijing, but now I can't find any media references to one outside of this article from Sunday. (FYI, Sunday's API peaked at 119).

This is the second day this year with an API above 200. The first was the day of the Mandarin Oriental fire.

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Update 3/19/09: Check out this terrific NASA image from Sunday:

Again, this was Sunday, whose API was 119. Still no word on the cause of yesterday's 268.
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looking for data biasing in 2008 blue sky data

Last year, a report by consultant Steven Q. Andrews highlighted apparent data biasing in Beijing's API data, particularly in the years 2006-2007. My take on his report (from last October) is here.

One of Mr. Andrews' core findings is that there were statistical anomalies in the frequency of Beijing's reported pollutant concentrations around the "Blue Sky Day" cut-off point. Specifically, there were too many reported values just below the cut-off, and too few just above, suggesting data manipulation to meet targets for number of Blue Sky Days. For reference, here is the excellent Figure 2 from Mr. Andrews' report:

Mr. Andrews' graph shows frequency of reported values vs. PM10 concentration, for which the Blue Sky Day cut-off value is 150 ug/m3.

With 2008 behind us, I decided to take a look back to see if a similar phenomenon existed last year. After querying Beijing's API data from MEP's datacenter, I parsed the data for each year into frequency by units of 5. In other words, I counted the number of days with API from 0 to 5, 6 to 10, 11 to 15, etc., all the way to 500. Rather than use PM10 concentration, I looked directly at API, for which the Blue Sky Day cut-off is 100. The results for 2006, 2007, and 2008 are graphed here:

Notes and Conclusions:

1) As expected, the 2006-2007 data biasing identified by Mr. Andrews is clearly visible here. In 2006, there were 50 days with API from 96-100, but only 2 days with API from 101-105. In 2007, there were 56 days with API from 96-100, and only 5 days with API from 101-105.

2) As for 2008, to be honest, I'm not sure how to interpret the data. Although there is clearly no dramatic spike in frequency of reported API values just below 100 (a good sign), there are only 3 days with API from 101-105. I do not know enough about statistics to know whether or not this is significant. (For reference, there were 16 days in the range 96-100, 9 days in the range 106-110, and 12 days 111-115). Anyone have any insights?

Related posts:
summary of beijing's 2008 air quality
beijing meets 2008 blue sky day target
problems with the "blue sky day" metric

evidence of pollution spike from mandarin oriental fire

I posted yesterday that the API of 307 would be classified by the US EPA as hazardous, and I wondered if it was related to the Mandarin Oriental fire. Today, both Xinhua and China Daily mentioned yesterday's highest grade pollution amid stories about the fire. China Daily even hinted that human health impacts from the pollution spike should be counted in the total cost of the fire (though to be fair I'm not exactly sure what they mean by "sphere"):

The total cost of the disaster has not been calculated, the fire department said, but the environmental bureau in the capital recorded a maximum grade for air pollution due to Monday's fireworks sphere.

Also today, we have a new data point implicating the fire as the key cause of yesterday's asphyxiating pollution. Take a look at MEP's graph of the last 30 days of API data:


We've seen some dramatically rapid air quality changes in the past here in Beijing, but I can't remember ever seeing a spike like this that could be directly tied to a single event.

Lastly, I think it is interesting to note in the above graph that there is a slight rise, but no dramatic spike, in pollution just after Chinese New Year's Eve (the impact of which would have shown up in the January 26th data point), despite the fact that the sky that night looked like this:


Image in graph: https://docs.google.com/View?docid=dggh5mp6_0cmqqrrdb
Fireworks image: Boston.com's The Big Picture

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Update 3/11/09
I know this happened a month ago, but I feel I should note that a commenter below pointed out that the Beijing EPB issued an explanation for the 307 API pollution spike. The explanation did not reference the fire, only the fireworks:

燃放爆竹带来今年首个重度污染天
2009-02-10

受不利气象条件和元宵节燃放烟花爆竹的双重影响，今天北京出现了今年以来最严重的污染天气，空气质量五级，污染程度达到了重度污染。

据市环保监测中心的监测数据显示，由于风速小、大气层稳定，大气污染物扩散条件变差，9号白天我市已经出现了轻微污染；晚上19点开始，由于元宵节燃放烟花爆竹，污染物浓度迅速上升，并且长时间维持在较高水平。19点到凌晨4点一直在每立方米400微克以上，其中21点时浓度最高，达到每立方米810微克，早晨5点为399微克每立方米，开始降到每立方米400微克以下。但由于受到静风等不利气象条件的影响，污染物浓度下降速度缓慢。

通过多年不间断的控制大气污染措施，本市出现5级重度污染的天数已经屈指可数，上一次重度污染天气出现在去年的5月29号。

Rough translation:
Setting Off Fireworks Brings This Year's First Heavy Pollution Day
2009-02-10

The dual impact of unfavorable meteorological conditions and the setting off of fireworks for the Lantern Festival led to Beijing's first severe pollution day this year. The air quality grade was 5, heavily polluted.

According to data from the environmental monitoring center, due to low wind and stable atmosphere, the atmosphere dispersion conditions changed to unfavorable. During the day of the 9th, the air quality was lightly polluted, but starting from 7pm, due to the Lantern Festival fireworks, pollution increased quickly and remained high. From 7pm to 4am, the PM10 concentration was above 400 ug/m3; it was highest at 9pm, reaching 810 ug/m3. By 5am, the concentration was 399 ug/m3, and began to drop after that. But because of calm winds and unfavorable meteorological conditions, the drop in pollution concentration was slow.

Through the continuous implementation of air pollution control policies, this city has experienced fewer and fewer grade 5 pollution days. The last grade 5 pollution day was last year on 5/29.
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warning: beijing air today is hazardous

Beijing's API today is at 307, corresponding to a PM10 concentration of 426 ug/m3. The US EPA calls this "Hazardous - Health warnings of emergency conditions. The entire population is more likely to be affected." China, on the other hand, merely calls it 重污染, heavy pollution.


I wonder if this is related to the Mandarin Oriental fire?


Image: The Beijinger
Another recommended link about the fire:
https://docs.google.com/View?docid=dggh5mp6_0cmqqrrdb

Much more info about China and US API designations in this related post:
12/9/08: stay inside today - beijing api at 246

other databases of chinese air quality data

Sorry about the deluge of posts today. I've recently returned to China after some time away in the States and am playing catch up on everything I missed.

Here I'm posting two additional databases of Chinese APIs outside of MEP's datacenter. Neither database has new data outside of the government-issued API data, however.

First, the Clean Air Initiative for Asian Cities has excellent China air quality data sets available for downloading. For example, Beijing APIs from 2000 to mid-2008 (along with tons of analysis) available on this page. Note that data for other cities may be downloaded at the bottom of the page. Note also the excellent API to pollutant concentration converter on the right.

Second, in late December, Imagethief posted "all the data you ever wanted on Beijing and Shanghai air pollution." In the post, he links to a 5MB Excel file containing daily API data for Beijing and Shanghai from 2000 through mid-2007. The spreadsheet also contains a lot of analysis.

Some day I'll post my own spreadsheets, but that will require me to clean them up (a lot) and also figure out a way to share files easily. I'm sure there's a way, I just haven't looked into it yet.

In any case, as you cut through the data from the above sources on your own, let me know what you discover!