summary of beijing’s 2011 air quality

Each year for the past few years around this time, I’ve posted an overall summary of Beijing’s annual air quality (links to 2010, 2009, 2008). Although I’ve had less time this year to update this blog regularly, I thought I would come out of hiding this weekend to take a look again at overall trends.

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:

beijing air quality trends 00-11 v2

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‚Äôs 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.

One Response to “summary of beijing’s 2011 air quality”

  1. foggybeijing says:

    Hi Vance,
    thanx for this detailed report. This is super-valuable information as usual.
    We’ve made a few charts about 2010 versus 2011 here:
    (this is only based on the data from the US Embassy).


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