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.

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).>

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:

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.

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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.
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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.

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.

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).