summary of beijing’s 2010 air quality

Happy New Year! For each of the past two years around this time (link to 2008, link to 2009), I’ve posted a summary of the previous year’s air quality in Beijing. This post contains some data and notes on 2010.

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:

beijing air quality trends 00-10
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

3 Responses to “summary of beijing’s 2010 air quality”

  1. Louie says:

    Thanks for the annual wrapup, Vance — do you know if Shanghai’s MEP released a similar review?

    One big picture reflection, is that China’s rating system is really distorted if you are used to international standards.

    Here in Shanghai, the air regularly rates in the top 3 out of 7 grades: Excellent, Good, or Minor Contamination (no Crazy Bad for us!). Before patting ourselves on our backs for living in such a paradise and going out for a jog, consider what this really means.

    On a day rated “Excellent” for particulates (API of 50), you would actually be breathing in over twice the particulates established by the WHO as the annual safety threshold (20 ug/m3). On a “Good” day (Class II, API of 150), this would be nearly 8x the international limit.

    I have not seen a chart that compares and converts APIs of China with other countries, but in the absence of that, it’s better to learn to rely on numbers and ranges instead of relative subjective descriptions.

  2. Vance says:


    I’ve never investigated what sorts of overall air quality evaluations the Shanghai EPB releases. I just glanced quickly at the Shanghai EPB’s website and found this page:, which I assume you’ve seen, which has weekly summaries and annual environmental reports. I should find the time to post separately on the results of Shanghai’s annual report as compared with Beijing’s.

    Regarding your comparison to the WHO, to be fair, the WHO’s daily PM10 limit is 50 ug/m3, which does fall in China’s Grade I “excellent” range. The more stringent annual limit, 20 ug/m3, is of course much more difficult to meet (and probably more important for long-term exposure effects). Also, a Chinese API of 150 would be Class III, Slightly Polluted (轻微污染), and would not fall within China’s ambient air quality standards. I think what you mean is PM10 value of 150 ug/m3, which would be an API of 100. This would indeed be over 8x the annual limit, but only 3x the daily limit.

    My point isn’t to sugar coat the air quality (I have noted repeatedly on this blog that Beijing’s annual PM10 value is 6x worse than the annual WHO standard), but I do think it’s important if talking about a single day to compare against the WHO’s daily limit, not the annual limit.


  3. Sanmeet says:

    Hi Vance,

    Is there any way for me to get the air quality for 2000-2010 or for any other year. I am doing a project on air pollution for beijing and can’t seem to find any data, other than daily ones. The website you directed to is in Mandarin.


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