BeijingAirblog.com

What i reported below seems to be nothing new under the sun; the New York Times carried an article yesterday referring to a study that says:

..the city changed its method for measuring pollution in 2006. In particular, officials stopped including readings from two stations in polluted areas and began using readings in three other stations in less polluted locales. Without this switch, Beijing would have fallen far short of its goals in 2006 and 2007 for the number of days that met national air quality standards, according to the study.

Mr Steven Andrews, the author of the study (in his original Wall Street Journal op-ed) also mentions the serious flaws in the Blue Sky days claims as i reported six weeks ago here. It seems the NYT contacted the relevant Chinese authorities to comment on this, but the only response they got was that the situation is improving visibly.

Mr. Andrews also found that ratings began to change after officials set targets for every monitoring station in the city. He said this political imperative coincided with a rising number of days that rated just below the break point of 101 to qualify as a Blue Sky day.

But it seems that people at the top of the system start to see the value of reliable data; there will be a national pollution survey starting in February 2008, calling for ‘true, credible’ data, and no officials will be punished for bringing bad news(!). Unfortunately the results of the survey will only be publicly available in 2009, way after the Olympics…

Thanks to Deep Lung and Osmo for pointing out this change in the list of the Beijing Environmental Protection Bureau’s monitoring stations. I assume this is the agency that passes the daily API value to SEPA for its national listing, so it is important to understand how the value is calculated.

Pre-2008 there were 27 stations in the list (for example 25 Oct 2007) and from this year there are still 27 stations (for example 8 Jan 2008). Note that the first line in both lists is the average; it looks like this is the number that SEPA uses for Beijing- although it does not seem to be the normal average of (sum/number of stations), maybe they use the actual PM10 values to calculate the average and convert to API afterwards.

However, more interestingly, if we look at the above picture, we see that the number of stations in the central districts have decreased:

• Dongcheng: 2 to 1
• Chaoyang: 3 to 2
• Fengtai: 3 to 2

And extra stations in Miyun, Daxing, and Yangqing. So the sum remains 27 stations, but 3 rather central locations have been removed, and 3 created in the outlying districts where the API is usually lower, so the average will definitely be lower from day 1; seems like a rather cheap trick doesn’t it?

Praise to the Chinese authorities for their successful efforts to reach the target of 245 Blue Sky Days (aka Clear Sky Days) of 245 in 2007, and yes it were exactly 245 days out of the 364 published values (SEPA) as reported by China Daily, despite the record breaking horrible last week of the year; also see my earlier post about this amazing feat.

Further analysis of these daily API values show an average API of 100.69 which is a bit better than 2006 (average=110) and slightly worse than 2005 (average=99); i wouldn’t say there is a visible trend in this yearly averages (also see previous post). Below is a graph of the entire year (click on image for larger file).

I cut off the graph at 200, above which EPA regards as ‘very unhealthy’ (purple level) and triggers a health alert in the USA. We had 11 days like this in 2007, but i did not hear any alerts. In Hong Kong this is the ’severe’ black level.

The green line at API 50 is the guideline for WHO (see this post, this is for the 24hr average; the WHO actually recommends 20 as guideline for annual average) and the upper limit in the EU (see this page). We stayed under this limit 32 days in 2007, that is less than 1 in 11 days. The red line at API 100 is the border of the famous Blue Sky Days, and the level up to which the authorities consider the air good enough for athletic competition. This level also mysteriously matches the annual average for 2007, which could also lead us to the conclusion that logically 50% of the days should be higher than 100 and 50% of the days lower (assuming a ‘normal’ distribution - Laplace-Gauss ‘bell’ curve), but nature in Beijing does not seem to obey this law as i have reported here. We got 67% below the average. Wikipedia on this ‘bell’ type of distribution:

The importance of the normal distribution as a model of quantitative phenomena in the natural and behavioral sciences is due to the central limit theorem. Many psychological measurements and physical phenomena (like noise) can be approximated well by the normal distribution. While the mechanisms underlying these phenomena are often unknown, the use of the normal model can be theoretically justified by assuming that many small, independent effects are additively contributing to each observation.

If anybody can give me a good reason why the distribution of API values over 1 year would not look like a bell curve, please let me know. The New York Times (29 Dec 2007) has mentioned this issue as follows:

Beijing has had 65 days that rated between 95 and 100. That bulge just inside the break point has attracted attention on Web sites and even at one foreign embassy, which compiled a statistical analysis casting doubt on the Blue Sky results, though the embassy’s officials refuse to discuss the findings.

Du Shaozhong, deputy director of Beijing’s Environmental Protection Bureau, said the ratings were not manipulated. “People used to ask me if the ratings are scientific, or if we are playing any tricks,” Mr. Du said. “But this is most advanced equipment in the world.”

Today SEPA published an API of 500 for 28 December 2007, that actually means the the average from 12:00 noon 27 Dec to 12:00 noon 28 Dec as explained here. As we can see on the Beijing bureau website, most monitoring stations noted 500, with the lucky people in Miyun (the far northeast of Beijing province) the only ones staying under 200. AFP quotes the BEPB ‘this is as bad as it can get’ and reports that the Beijing Evening Newspaper did warn residents to skip their outdoor morning exercises.

Due to strong winds this morning, the situation looks a lot better, as you can see on the below pictures taken at 14:00, compared to my post of a couple of days ago. Visibility seems to be more than 1km again.

Today 27 December 2007 SEPA reports an API of 421 for Beijing; that is the worst day this year. In 2006 we actually had 5 days that were even worse, with API 500, that is the maximum value, the system does not record higher numbers. If we look closer at all monitoring stations in Beijing, we see that this 500 level was reached in many locations today throughout the city. The lucky people in Changping and Miyun stayed under 200.

This morning 10am i took this picture from our window; i estimate the visibility was 250 meters. Amazingly there seems to have been no significant flight delays at the airport, at least not more than usual.

SEPA calls any API above 300 ‘heavily polluted’ and gives this advise: ‘The aged and patients should stay indoors and avoid strength draining; the ordinary should avoid outdoor activities.’ The only reason i went outside today is to buy a new filter cartridge for our air filter. Below picture shows new filter on the right, and old one of left, after 6 months use in Beijing, Lido area. Also bought a new vacuum cleaner with HEPA filter.

With an API of 280 on 25 December, and 269 on 26 December, i wish we would have left on holiday a bit earlier. This is really horrible, the 2 worst days of the year, except for 5 January which had 322. On a really good day, we can see the China World III tower and the new CCTV tower (first image, 28 Oct 2007, API=27, 5th best day of the year), but this last week it has been like the second picture, one grey mass, not even enough light to take a sharp picture (26 Dec 2007, API=269, 3rd worst day of the year).

If i am not mistaken, we stand at 244 ‘clear/blue sky days’ at the moment, and it does not look like we’ll be able to add one more this year to get to the target of 245. This count does not include 20 August because there is no data on the SEPA website for this day, it was the last day of the 4-day experiment with car restrictions, and somehow the measurement for 20 August seems to have been lost.

December has not been a good month for Beijing’s air quality; NASA offers this satellite image taken on 17 Dec, where we see a giant cloud of haze covering the East China plains (thanks to Danwei for the link). Beijing’s API was only 78 that day, indeed a ‘Clear Sky Day’! According to SEPA data, the 4 near cities of Tianjin, Shijiazhuang, Qinhuangdao, Taiyuan, all had APIs higher than Beijing on that day, which is quite unusual, so i really don’t know what to think about the Beijing numbers anymore.. (also see my page local vs regional)

In the above graph we see that we only got 12 ‘Clear Sky Days’ out of 20 so far this month, which is slightly below the target of 67% (245 days per year). The average API for these 20 days is 101, which corresponds to a PM10 concentration of 150 microgram/m3 which is by all standard really really bad. In fact, in Belgium, my native country, these last few days there are special temporary measures to reduce the maximum highway speed from 120km/hr to 90km/hr because the authorities expect increased levels of fine dust (PM10), above 70 microgram/m3 which is alarming in Europe, but only half of what we have here on average!

This picture comes from Belgium’s monitoring authority IRCEL; it shows the alarming situation (to European standards) that about half of the country (orange-red area) has a PM10 higher than 70 micrograms/m3 (which corresponds to an API of 60), and that our average level in Beijing of 150 micrograms/m3 (API 100) is really far into the red, hardly reached in Belgium on the worst days!

Still a long way to go for Beijing, but yesterday i was extremely happy to see that at last a bike rental network is expanding throughout the city with more than 50 rental points, and flexible terms. The target is to have 50,000 rental bikes out there for the Olympics.

It seems Beijing will reach its Clear Sky Days target of 245 days for 2007; with 33 days to go, we already have had 229 days with API less or equal to 100, so we only need 16 more (leaving out the mystery day of 20 August). Applause for all the officials who worked hard to accomplish this. But wait, there is more to this, read on.

If we change the interpretation of Clear Sky Day to an API less than 100 (not counting the days with exactly 100) then we have only 220 days and still need 25 out of 33 which is most probably not going to happen, so the difference between making the target and not making it is in fact very small.. But SEPA does include an API of 100 in its grade 2 ‘good’ so it counts as a Clear Sky Day.

Making a histogram of the API values of 2007 (counting the occurences of values), we see that the most occuring values are:

• 98 (21 days)
• 99 (11 days)
• 100 and 95 (both 9 days)

Isn’t that wonderfully helpful that the values tend to stay just on the good side of 100? The value of 101 has not even occurred ONCE, and see the amazing drop after 100.. The guy in charge of publishing these API data deserves a promotion, the government’s target will be met!

Last week i noticed that the SEPA English homepage did not display the updated API numbers (it did work on the Chinese homepage), so i wrote them a short email to ask to fix it, to the contact email address (info2@zhb.gov.cn) that they provide on the same page. One week later still no answer, but the API values are back now, although clicking to get the complete list gives an error ’sorry, no record’ and obviously the pollution grades are messed up as well.

Also their latest news release ‘China reports decline in major pollutant emissions (20071114)’ is a dead link, hallelujah.

From the Chinese homepage, you can still get to the list of daily API values, and you can make queries using the section at the bottom of the page. There you can find out we had an API of 269 on 25 November!! That is the second worst day this year, after 5 January. Strange that our near neighbour Tianjin did not have any special peak on that day.

This week the first hydrogen refueling station in Shanghai was opened for fuel cell vehicles (FCV). The UN will sponsor a fleet of fuel cell buses by 2009, as it has done in Beijing. The articles state that in Beijing and Shanghai, public buses are among the main contributors to air pollution, so that is definitely good news, although in Beijing the project seems to be limited to 3 buses only- the official website (in the usual horrible official Chinese website style) has more information on the challenges. But something seems to be moving because SEPA has mentioned that it is working with various ministries to introduce a pollution tax for car drivers for exhaust of carbon monoxide and sulphur dioxide.