I won’t repeat my methodology in this post (it’s described in detail in previous years’ summaries); let’s just jump straight to the conclusions.

Using MEP’s own data, I calculate that Beijing in 2011 had a Blue Sky Day count of 286 and a calculated average PM10 concentration of 114 ug/m3. Trends of Beijing’s Blue Sky Days and PM10 concentrations are shown here:

–
Update 1/29/12: I originally posted a 2011 Blue Sky Day count of 285, along with a comment (below) that I thought the Beijing EPB’s count of 286 was an error. I concluded this based on the fact that MEP’s datacenter contains 365 data points for 2011, of which only 285 are Blue Sky Days. It turns out, though, that one day (October 28th) is missing from the data set, while another day (November 1st) is duplicated. I did not notice this in my initial analysis. The duplicated day, November 1st, was not a Blue Sky Day. If we assume that the missing day, October 28th, was a Blue Sky Day (which appears to be supported by Beijing EPB data), then the Beijing EPB’s count of 286 is correct. The graph above has been updated to account for the new Blue Sky Day total. Note that this change does not affect my calculated PM10 average, which matches that reported by the Beijing EPB.
–

The good news:
According to MEP’s data, Beijing’s annual average PM10 concentration (shown in the dark blue curve) decreased slightly from 2010 to 2011. This is a welcome change after the stagnation we saw from 2008-2010. From the perspective of this metric, it appears as though Beijing is showing some (minor) progress again in improving air quality. Also encouraging was the fact that the number of Grade I days (what China calls “excellent” air quality) went up significantly, as shown in the light blue curve in the above graph. The number of Grade I days was bolstered by an absolutely incredible January 2011, which was Beijing’s best air quality month in at least a decade.

Also in the “good news” category, though independent of analysis of MEP’s air quality data: In the last two months of the year, we saw a massive proliferation of air quality discussion among the public and in the media here unlike anything we have seen since the Olympics. Why now is not so clear – in early November I postulated that it was due to a combination of a few terrible air quality streaks in October and growing public awareness of air pollution driven by social media (see similar analysis in AFP, WSJ, and Time). Regardless of the specific reasons, the result has been incredible public pressure on the Chinese government to take more aggressive action on monitoring, reporting, and controlling air pollution, especially PM2.5. Incredibly, this pressure appears to have succeeded in driving some change: most notably, MEP has now publicly committed to a timetable for measuring and reporting PM2.5; the People’s Daily even noted, “The media called the schedule published at the end of 2011, ‘A symbol of the public opinion’s victory in the air protection battle.’” More analysis of the specific PM2.5 targets and timetables in another post.

The bad news:
Beijing’s air quality still does not meet China’s own air quality standard, and is still nearly six times worse than the recommended particulate matter target set by the WHO. In other words, the air here is still just awful. (We even saw reports this year (the first in the Chinese media that I can remember) directly linking air pollution episodes to acute health impacts and even grounded flights.)

And, although I claimed some minor progress earlier, the progress was far from consistent. Removing the data from the uncharacteristically wonderful month of January, the average PM10 concentration for February through December 2011 turns out to be 119 ug/m3 – essentially unchanged from 2009 and 2010. This directly contradicts Beijing EPB comments made at the end of January that that progress was “far from one-off.”

Even more bad news: the 2011 Blue Sky Day count exceeded Beijing’s goal of 274, but came up one day short of last year’s total of 286. This represents the first time in at least a decade that the annual number of Blue Sky Days has decreased year-on-year. (I should note here, however, that the Beijing EPB today reported 286 Blue Sky Days in 2011 – the same number as in 2010 – but I believe this to be an error. The Beijing EPB reported 19 Blue Sky Days in October, although my careful count of the data on MEP’s datacenter shows just 18 that month. I’ll keep my eye on the public statements to see if they fix this error in subsequent annual summaries.) (Edit 1/29/12: See note above regarding the resolution to the data discrepancy noted in this paragraph.)

Therefore, by China’s own currently reported data (both PM10 numbers and number of Blue Sky Days), Beijing’s air quality improvement efforts are really showing negligible progress. Even worse: Chinese data currently only cover PM10, not PM2.5, which, according to recent Chinese media reports, is actually getting worse here in Beijing. This is bad news, for a few reasons. Mainly, it’s bad news because the health impacts of PM2.5 are considerably worse than those of PM10. However, it’s also bad news politically for China, and hints at the challenges MEP will have when it begins reporting PM2.5. After claiming consistent progress for many years, how will MEP/Beijing EPB manage the fact that their new indicator shows the opposite trend?

Much more news to report on from this year, including Steve Andrews’ scathing critique of Beijing’s air quality from earlier this month, but further analysis on that will have to wait until next year.

Happy New Year everyone! Looks like it’s going to be an excited 2012 for all us air quality wonks.

Well, now February has passed, and the air quality results are in. Unfortunately, there is little to be “ebullient” about. There were just 18 Blue Sky Days in February (64%), and I calculated the average PM10 concentration over the month to be 144 ug/m^3. In addition to being well over twice as bad as January’s (during which the average PM10 concentration was just under 60 ug/m^3), this level is almost 50% worse than China’s own national ambient air quality standard, and over 7x worse than the WHO’s recommend annual limit.

The average was skewed by the four absolutely horrible air quality days from February 21-24, but even without considering those days, the average PM10 for the month was still 107 ug/m^3, above China’s standard and 5x worse than the WHO’s.

(As always, my data sources are MEP’s datacenter for API data, which I convert to PM10 concentration using formulas described here.)

I am still waiting for the Beijing EPB to issue their monthly air quality report, and will try to check in again once they do.

BEIJING – Heavy fog with a visibility of around 1 km persisted in Beijing for a third day Wednesday, keeping the city’s air pollution at the most hazardous levels measured this year.

The municipal environment bureau’s readings indicated the heaviest air pollution on Wednesday was monitored in Daxing district in southern Beijing, where the air quality index (AQI) reading hit 362.

The AQI ranges from 0 to 500: the higher the number, the more severe the pollution. Readings over 300 are considered hazardous.

The average AQI reading for the city Wednesday was 207, down from 270 on Tuesday and 333 on Monday.

The highest AQI reading over the last three days – at 394 – was recorded in the eastern Chaoyang and northern Haidian districts on Tuesday.

The Beijing Meteorological Bureau said a weak cold front would hit the city on late Wednesday to dispel haze. Winds, however, were unlikely to completely clear the air pollution on Thursday.

The article seems fairly straightforward, though there is one very surprising detail: the terminology they are using to describe the air pollution is the United States’ terminology, not China’s. Two differences:

1) China’s own index is called the Air Pollution Index (API), not the Air Quality Index (AQI), which is what is used in the US.

2) China’s system does not use the word “hazardous” to describe index levels above 300. “Hazardous” above 300 is the US’ terminology. China’s system simply calls this “heavy pollution” (重污染), without a value judgment of the danger. (”Hazardous” might be better translated as 危险 or 有害.)

Does this shift signal the impact of the US’ Embassy’s BeijingAir Twitter feed on guiding air quality discussion, at least among the English-speaking population in Beijing, or am I reading too much into it? (I asked similar questions in two posts in 2009 when the English-language China Daily openly questioned China’s system in light of the Embassy’s data.)

Regardless, Chinese language sources appear to be uniformly using the Chinese terminology. This Xinhua article in Chinese even includes a glossary, though it carefully avoids any judgments like “hazardous,” preferring the less direct “heavy pollution” (重度污染). The article does note, though, for index levels above 300, “elderly people and those with heart or lung diseases should remain indoors and reduce physical activity…and…the general population should avoid outdoor activity.” (老年人和心脏病、肺病患者应停留在室内，并减少体力活动…一般人群应避免户外活动。)

and this from space (2/20 photo from NASA):

From a data perspective, mashed potato air means three consecutive days of MEP’s API above 200 (including a 2/20 peak of 333 – equivalent to a daily average PM10 concentration of 446 ug/m3), the US Embassy’s BeijingAir Twitter feed consistently reading “Hazardous” or “Beyond Index” (PM2.5 concentrations peaking above 500 ug/m3), and the China National Environmental Monitoring Center’s new hourly air quality data showing…well, no particulate matter data at all for at least the past 48 hours for most centrally-located stations. This is disheartening, because it’s extreme episodes like this during which people – especially at-risk populations – need that data the most. The Wanshouxiguan (万寿西官) station does have hourly PM10 data, which show a peak near 480 ug/m3 (graph below shows that station’s hourly PM10 data from 2/21 6pm to 2/23 6pm):

For context, remember that the WHO’s daily recommended PM10 limit is 50 ug/m3, while the annual limit is 20 ug/m3.

Unfortunately, I have no time this week to run additional data analysis or provide more lengthy commentary, though I would like to repeat my previous comment about the Beijing EPB’s claims of credit for January’s excellent air quality: “If January’s good air quality was ‘far from a one-off,’ does this mean we can expect this much improved air quality to continue? (If it doesn’t, then I will be very curious to see what explanation is offered (if any) when the air pollution levels go back up to more expected levels for this time of year.)” The Beijing EPB issues monthly air quality summaries on the last day of each month, so let’s see what they say next Monday.

Lastly, just one criticism of the AFP story that’s going around:

BEIJING — Thick smog blanketing Beijing went “beyond” measurable pollution levels on Monday, the US embassy said, as a Chinese official warned people to stay indoors and avoid outdoor activities.

Actually, the pollution levels are still measurable, and reported. You can still see the pollution level, as highlighted here (in this case, a PM2.5 concentration of 515.0 ug/m3):

“Beyond index” doesn’t mean the pollution can’t be measured, it just means that the pollution level is beyond the US’ standard system for categorizing, which maxes out at 500. (Though we all know what it’s really called.)

Although we have seen gaming of the Blue Sky Day metric in the past, in this case both the data and public observation support dramatically cleaner air quality over January 2011 than in months and years past.

On the data side, for the 36-day period December 23, 2010 to January 27, 2011, I calculated an average particulate matter concentration of around 64 ug/m3 in Beijing. (API to PM10 concentration methodology here.) While this is still well above the WHO’s recommended annual limit of 20 ug/m3, this pollution level is less than half of that over the same period in 2009-2010, and is actually on par with the pollution levels during the Olympic (57 ug/m3) and Paralympic (71 ug/m3) periods, which were widely regarded as successful.

Looking at the data another way, an astonishing 18 of the past 36 days have been Grade I “excellent” air quality days in Beijing, which means the API is 50 or below. In 2001, Beijing only had 12 Grade I air quality days the entire year.

From a public observation perspective, I offer up for evidence the conversation I mentioned in my last post which made me start thinking about the streak, this e-mail I received two days ago from another friend:

I’ve been meaning to ask but since pretty much Christmas Eve I feel like has been the best stretch of air quality since I landed here…even better than the Olympics (which I caught the tail end of). My general air quality test is how well I can see the mountains from Tsinghua or Andingmen bridge. Rarely has there been a miss. I must have clearly seen stars all but a handful of nights and I can’t think of a day that’s looked polluted from start to finish. Are my eyes merely deceiving? Is the wind just being very helpful? Or has there actually been a drop locally?

and finally, the Beijing Air feature from the Asia Society, which features daily pictures, monthly averages, and weekly comparisons of Beijing’s air quality with that of New York. Here’s the past week comparison between Beijing (top row) and New York (bottom row):

They note, “This week has been by far the cleanest in terms of both blue-ness and air quality stable performance. Even New York looked less impressive.”

So why has the air quality been so uncharacteristically good recently? Unfortunately, I have no data-backed theories, although I would guess it’s a combination of existing pollution control programs and standards beginning to bear fruit, economic slowdown prior to the Chinese New Year holiday, and really favorable weather patterns that have prevented any pollution from building up. (Perhaps the lack of pollution build-up is also related to similar weather patterns that have prevented any measurable precipitation in Beijing since October 23rd.)  Regardless, it’s a great air quality start to 2011. Let’s see how much longer the streak can go.

Here’s what I found. Going back to 2001, I only found 6 streaks of 25 or more consecutive Blue Sky Days. They were as follows:

6/24/06 – 7/28/06 (35 days)
7/31/06 – 8/24/06 (25 days)
1/21/08 – 2/18/08 (29 days)
7/28/08 – 8/28/08 (32 days)
8/30/08 – 9/29/08 (31 days)
8/19/10 – 9/14/10 (27 days)

The two streaks in the summer of 2008 were clearly linked to the temporary pollution reduction policies put in place for the Olympics and Paralympics. I’m not sure what caused the other streaks, especially the excellent summer of 2006.

The current streak began on 12/23/10. Let’s see how long it can go! Track it yourself here at the MEP datacenter.

My data source, as always, is the datacenter of the Ministry of Environmental Protection, which archives historical Beijing air quality data here. (Note that I’m using the daily averages, not the recently released hourly data.) All I’m doing is copying the data into Excel, then parsing it and doing some conversions to look for patterns. The most important conversion is converting Air Pollution Index (API) to ambient particulate matter (PM) concentration, using the equations described here. This is important for two reasons. First, the conversion allows for averaging, which should not be done with API data directly. Second, ambient PM concentration is a much better indicator of the health impact of air pollution in Beijing, allowing for direct comparison to international air quality standards and existing health effect studies.

Now on to the data. The datacenter reports 363 data points for 2010 (3/15 and 5/21 are missing). Assuming those two days were Blue Sky Days yields a Blue Sky Day count of 286 and a calculated average PM10 concentration of 122 ug/m3. The Blue Sky Day count of 286 has been confirmed by the Beijing EPB, but the PM10 concentration value probably won’t be released for another few months.

As a reminder, Blue Sky Days are days for which the API is at or below 100, which China deems “excellent” or “good” air quality. Cities count the annual number of Blue Sky Days as an easily-understood measure of air quality progress, although the metric has been gamed in the past and is actually scientifically meaningless.

This figure shows trends of Beijing’s Blue Sky Days and PM10 concentration since 2000:

The Bad News: Beijing’s air pollution levels, as represented by ambient particulate matter concentration, have remained flat for the past three years, actually getting slightly worse from 2009 to 2010. This is consistent with results reported in mid-2010. Beijing’s air quality still does not meet China’s own air quality standard, and is six times worse than the recommended particulate matter target set by the WHO.

The Good News: Beijing’s 286 Blue Sky Days in 2010 far exceeded its target (266), and miraculously managed to beat last year’s total by just one day. In addition, there was a slight increase in the number of Grade I (”excellent”) air quality days as compared with 2009 (as shown in the above graph in light blue). This is dramatic turn-around from the way things looked in the first half of the year. Given that over 700,000 vehicles were sold in Beijing in 2010, I suppose the fact that the pollution didn’t get even worse can be viewed in some respects as a success.

Beijing’s Environmental Protection Bureau really struggled to call 2010 a success. On December 31st, they released a short note stating, “今年我市空气质量二级和好于二级的天数累计达到286天，占78.4%，比去年多1天，实现了空气质量连续12年持续改善,” meaning, “This year, the number of days in our city meeting the Grade II or better air quality standard totaled 286, representing 78.4% of all days, one more than last year. This has realized 12 consecutive years of air quality improvement.” The last statement is highly dubious, especially given my preliminary conclusion that the average PM10 concentration was higher in 2010 than 2009. It will be interesting to see how and if the EPB’s statements change when the PM numbers are released in the environmental annual report later this year.

Related posts:
Summary of Beijing’s 2009 air quality
Summary of Beijing’s 2008 air quality

“Enthusiastic congratulations for the successful launch of the air quality reporting system for key cities!”

“Introduction to the China National Environmental Monitoring Center

The China National Environmental Monitoring Center is a government-affiliated supporting research institution (事业单位) directly administered by the Ministry of Environmental Protection. It includes the national environmental monitoring technology center, network center, data center, quality center, and training center. The primary responsibilities are national environmental monitoring and environmental monitoring technology development, in order to provide monitoring information, reports, and technical support to guide national environmental management and policy.”

“Introduction to the Reporting System

The real-time reporting system for air quality in key cities automatically reports measured ambient data for sulfur dioxide, nitrogen dioxide, and inhalable particles. Hourly average data are presented for both individual monitors and entire cities. Data for individual monitors represent the average over the previous complete hour; for example, the data for 4pm represent the average value from 3pm to 4pm. Data for a city represent the arithmetic average of all stations in that city.

The data in the system are updated once per hour. Because the data transfer requires some time, there is currently a reporting lag of half an hour. For example, the data for 3pm will be reported at 3:30pm. When the monitoring equipment is undergoing calibration or encounters some communication or power error, there may be no data for that corresponding station.”

“Introduction to the Reporting System

In accordance with the technical standard requirements of air quality monitoring, the air quality automatic monitoring data must be audited before it can be considered as part of an air quality assessment. However, in order to fulfill the public’s right to know in a timely manner, this system automatically reports the real-time data before they have been audited.

The source of data in this system is national-level ambient air quality automatic monitoring stations, not including local-level automatic monitoring stations.”

“The relationship between real-time reported data and daily reported data

- The real-time reporting system for air quality in key cities reports the hourly average concentrations of three types of pollutants – SO2, NO2, and PM10 – for the entire city and at each monitoring station.

- The daily air quality report that has been in place since the year 2000 reports the 24-hour average air quality for key cities. In order to fulfill the need of afternoon air quality reporting by the media, the calculation for the daily report covers data from noon on the previous day to noon on the current day. After the average daily concentrations of each pollutant are calculated, they are converted to an Air Pollution Index (API), which can be easily understood by the public.

- Because the API is based on a 24-hour average of each pollutant, China, like many countries, currently does not provide an hourly API. Therefore, the real-time reporting system will only report the hourly concentration of each pollutant. The 24-hour averages will still be used for the daily API calculation.”

In addition to providing data, the site is an extremely valuable resource for general information about China’s air quality, including air quality standards, definition of Air Pollution Index, impacts from air pollutants, main sources, etc. In many ways, the site is a like a very primitive version of the US EPA’s air quality public outreach site, www.airnow.gov. After what has seemed like a frustrating year for air quality in China, this is a wonderful development for which China deserves great credit.

The main address for the site is http://58.68.130.147/air/, with the actual data accessible at http://58.68.130.147/air/air/airtestpage.html. The site is currently exclusively in Chinese, and is developed in Silverlight, which is apparently a Microsoft version of Flash. (I had to download it from Microsoft’s website before I could view the site.) Because of the way the site is structured, it seems impossible to link to individual pages or copy/download data. This is an annoying and frustrating flaw in my opinion, but I’ll take what I can get for now.

I’m sure I will have many, many more posts about this new site and the treasure trove of data that’s available there. For now, though, let me just show a couple of examples of the type of information available:

This chart shows hourly concentrations of SO2, NO2, and PM10 from 7am this morning to noon at the Dongsi monitoring station in downtown Beijing:

This graph shows the hourly PM10 concentrations at that same individual station over the last 48 hours. The red line represents China’s daily air quality standard. The green line shows the previous day’s average.

Again, much more analysis to come, but for now my lunch break’s over and I need to get back to my day job. I’m happy to be bringing this positive report for a change, and look forward to providing more analysis and translation in the near future. In the comments section below, please feel free to ask specific questions about this new service and I’ll do my best to answer them.

A few days ago, the US embassy’s BeijingAir Twitter feed, which automatically reports Beijing’s hourly air quality, made headlines across the web by announcing that the air quality was “crazy bad.” Although the wording was quickly revised to the more politically-palatable “beyond index,” the impact was immediate. “Crazy bad” air was all the buzz of the blogosphere and at social events over the weekend; I have a feeling “crazy bad” would make it onto Beijing’s Word of the Year list, if there were such a thing. MyHealthBeijing’s Dr. Richard St. Cyr even suggested “Crazy Bad” T-shirts.

In this post, I’ll look a little closer at the data behind the Crazy Bad incident to see what we can learn. The graph below shows hourly and daily data from the BeijingAir Twitter feed along with official air quality data from the Ministry of Environmental Protection (available here, Chinese only). For clarity, I show all data in terms of particulate matter concentration, not standardized index. (I’ve converted MEP’s reported API numbers to PM concentration; for background on the difference and methodology, see this post.) Note that MEP’s data is reported for a 24-hour period from noon to noon, which is why the daily data changes at noon each day. The break in the red corresponds to the BeijingAir Twitter feed not reporting any data for a couple of days after the Crazy Bad incident.

This graph reveals some really fascinating info:

1) The Crazy Bad spike on Thursday and Friday last week was both preceded and followed by gorgeous, wonderfully clean weekend days. On 11/15, the air quality was, by all accounts, “good.” By 11/18, though, the air pollution had steadily risen to what the US calls “hazardous“/”crazy bad,” and China calls “heavily polluted” (”重污染”). After the steep rise, the air quality improved just as dramatically; MEP’s reported PM10 numbers dropped 297 points – from 334 to 37 – from 11/21 to 11/22 alone. This demonstrates just how quickly the air quality can change in Beijing – both for better and for worse.

Why did it change so quickly? The start of the heating season on 11/15? Possibly, although that wouldn’t explain the sudden drop beginning 11/20. To be honest, the answer is probably less dramatic: weather. Most day-to-day pollution changes in Beijing are caused by changes in temperature and wind patterns. If there are a few days of static air, or light winds blowing from the southeast and trapping pollution against the mountains to the north and the west, the pollution builds up very quickly. I should find the time to post separately about this.

2) MEP’s air quality data tracked the embassy’s with reasonable consistency. This is actually encouraging; we should be grateful at least for some degree of accuracy and transparency with official data. There are some differences, but we shouldn’t expect them to track exactly. This is because the MEP data is an average of multiple sites across the city, while the embassy data is just a single point. Plus, they are measuring slightly different things.

In the past, we have seen situations where rapid and very short-term pollution spikes highlighted by the BeijingAir hourly readings were not reflected in daily MEP averages, but that doesn’t appear to have happened here.

(As I point this out, though, I should also note that I do not intend to make excuses for or to justify China’s current reporting mechanism. For the record, I would like to see at least three immediate changes to China’s air quality reporting: hourly release of data, more representative descriptions of health impacts, and some sort of real-time alert system for at-risk populations to avoid exposure.)

Lastly, a few data highlights for the numbers geeks out there (background on international standards here):

US EPA daily ambient air quality standard for PM2.5: 35 ug/m^3
Peak PM2.5 concentration reported by BeijingAir, 11/19: 557 ug/m^3

WHO recommended daily limit for PM10 exposure: 50 ug/m^3
China daily ambient air quality standard for PM10: 150 ug/m^3
Peak PM10 concentration reported by MEP, 11/19: 430 ug/m^3