Friday, December 19, 2008

new york times blocked in china?

I have been unable to access the New York Times all day today, either from home or from work. A friend in the US tells me that the home page currently features the story "After 30 Years, Economic Perils on China’s Path." (Link is to the IHT version, which is not blocked here).

The apparent blocking of the NYTimes comes on the heels of the explicit acknowledgment by the Chinese government of their "right" to censor the internet:

China says within rights to block some websites (Reuters)

Is anyone in other parts of China (or elsewhere in Beijing) able to access the New York Times today?

Update 12/20/08: The Atlantic's James Fallows conducted an informal survey of readers across China, and concludes " is being blocked throughout China," noting that the pattern of inaccessibility is consistent with how China's censorship works. Earlier this year, Mr. Fallows wrote the most comprehensive article I've read about China's Great Firewall.

Also, an anonymous commenter below mentioned problems accessing, but I'm currently having no problems loading that site.

Update 1/15/09: I left China on 12/20 to go home to the States for almost three weeks. Since returning to China last weekend, I've had no trouble accessing the Times. Apparently, the three-day ban was lifted on 12/22.

Tuesday, December 16, 2008

beijing meets 2008 blue sky day target

Earlier this month, the Beijing EPB announced that Beijing reached the 2008 target for total number of "blue sky days" one month early. A "blue sky day" is defined as one for which the API is below 100, indicating "excellent" (优) or "good" (良) air quality.

The stated goal of this blog is to "explore miscommunication between China and the West on issues of the environment and beyond." As such, I want to highlight a major difference between how this story was reported within China and internationally.

Specifically, let's look at the Xinhua English language report and the China Daily report (domestic) vs. the widely distributed Associated Press report (international). As expected, the domestic sources are purely positive. Xinhua's lead is simple and dither-free:
Beijing fulfils "blue sky" day goal one month in advance
Beijing has met its 2008 target of 256 blue sky days as Sunday marked another day of good air quality.
China Daily's lead is even more decisive:
Clear days' target met before time
Determined efforts, special measures and good weather helped Beijing achieve its annual target of 256 blue-sky days yesterday, a full month before the end of the year.
Compare these to the AP's lead:
Beijing claims early victory over air pollution
BEIJING (AP) — Beijing said Monday it has already reached its target number of 256 "blue-sky days" this year, with the help of ambitious environmental measures the city imposed to cut emissions for the Olympic Games.
Two words - "claims" and "said" - in the AP lead jump out at me as setting a very different tone from the Xinhua and China Daily stories. The implication being that the truth may be different from what the Beijing EPB proclaims. And, indeed, this suspicion over data integrity is substantiated in the last three paragraphs of the AP story, three paragraphs that are conspicuously absent from the domestic China reporting:
Steven Andrews, an independent environmental consultant based in Washington, said Beijing's claims of improved air quality are not reliable because the city has moved monitoring stations to less-polluted areas and has varied the way it has measured pollutants since 1998.

"They've measured different things during that time period and it has a huge impact on the number of days that meet the national standard," Andrews said in a telephone interview.

Such inconsistencies mean that the increase in the number of blue-sky days may be due to the change of monitoring locations, rather than a reduction in overall pollution levels, he said.
For me, the discrepancy between the international and domestic reporting is deeply frustrating on several levels.

Perhaps most importantly, I am frustrated that Beijing's air quality data is (justifiably) not considered trustworthy by the international community, and that the Chinese media is forbidden (or just blind) to questioning it. As I have posted before, Steven Andrews' excellent analysis of Beijing's historical air quality data strongly suggests past data manipulation, in addition to his reasonable claim that one cannot directly compare the number of Blue Sky Days from different years due to monitoring station location changes. Until the Beijing government takes concrete steps to improve data transparency and independent confirmation, questions of data trustworthiness should and will remain.

On the other hand, though, I am frustrated because, due largely to the two-month shut down surrounding the Olympics, this is a year in which Beijing's air quality genuinely has been better. In other words, this is a year in which Beijing did not need to, and may not have, engaged in data manipulation to meet targets. Any yet, at a time when Beijing arguably deserves credit for achieving its Olympic air quality goals (and for taking steps to maintain air quality in the post-Olympic period), there still seems to be a strong sense in the international community that any success Beijing achieved is either fake or was achieved by cheating. Virtually every conversation I have with a non-Chinese about Beijing's air quality begins with, "well isn't it true that Beijing's air quality data is bogus anyway?"

In relation to the AP article, consider this statement:
Such inconsistencies mean that the increase in the number of blue-sky days may be due to the change of monitoring locations, rather than a reduction in overall pollution levels, he said.
While it may be true that the change in monitoring stations affected the number of days considered Blue Sky Days, this does not necessarily mean that there was not a reduction in overall pollution levels from 2007 to 2008.

My final point of frustration is really a technical issue with the number Blue Sky Days metric. Simply put, the number of Blue Sky Days metric is meaningless from a human health perspective, since what matters is average concentration of pollutants, not number of days below an arbitrary cut-off point. The value of the number of Blue Sky Days metric is not scientific, it's social; it's a way of packaging air quality information into a format thought to be easily comprehended by the public. I mention this only to say that what I am really curious about regarding 2008 is not number of Blue Sky Days, but rather average annual particulate concentration. It is only with that data (combined with whatever additional independent confirmations are available) that we will be able to make any real judgments about changing air quality.

Image: China Daily

Tuesday, December 9, 2008

stay inside today - beijing api at 246

Beijing's API broke the 200 mark today for the first time since May 29th.

Today's API reading of 246 - corresponding to a PM10 concentration of 382 ug/m^3 - would be characterized by the US EPA as "very unhealthy":

Here in China, this air quality is simply referred to as:

北京2008-12-09的API指数为 246 , 空气质量级别 Ⅳ1 级 , 今天北京空气中的首要污染物为 可吸入颗粒物 , 空气质量状况 中度污染 。

Translation: "Beijing API on 12/9/2008 is 246, air quality level IV1. Today's primary pollutant is inhalable particles. The air quality status is moderate-heavy polluted."

Sources and a brief discussion of US AQI vs. Chinese API follow:


Beijing API:
Conversion of Chinese API to PM10 concentration:
US AQI pollutant concentration breakpoints: For PM10, the breakpoints are almost identical to China's:

(Above image, US breakpoints. Below image, China's breakpoints)

More info on PM10:

Friday, November 28, 2008

update on fall air quality in beijing

Yesterday a friend commented that it seems like the air quality in Beijing this fall has been much better than last fall. Turns out he's right:

(For background, see this post on Air Pollution Index (API)).

Although the air quality since 9/21 hasn't been as good as it was during the Olympic period, the average particulate matter concentration in the air this fall has been over 20% lower than the same time period last year and almost 40% lower than the same time period two years ago. Perhaps the one-day-a-week car ban is working?

FYI, the average PM10 concentration this fall of around 100 ug/m^3 is actually right at China's annual air quality target, though still five times higher than the WHO recommended annual level of 20 ug/m^3.

Lastly, I want to show again a long time-scale graph of daily API vs. time in Beijing:

There are two main take-away messages from this graph:

1) The improved air quality of the Olympic period (7/20 - 9/20, 2008) is quite apparent.
2) We have yet to see a major pollution spike (say, API above 200) since the Olympics ended...

highlights from BAQ2008 - ICCT and diesel emissions

This is the third in a series of posts noting some random highlights from the BAQ2008 conference. Here I'd like to feature a few great slides I saw presented by Dr. Anup Bandivadekar of the International Council on Clean Transportation (ICCT). (Side note: Dr. Bandivadekar is the lead author of MIT's "On the Road in 2035: Reducing Transportation's Petroleum Consumption and GHG Emissions.")

The presentation I heard by him was called "Diesel Passenger Cars: Safeguarding Air Quality and the Global Climate in a Shifting Market."

The presentation begins with an introduction to the "diesel dilemma," which I will briefly summarize as follows: diesels are more efficient than gasoline vehicles (therefore are better for energy security / CO2 emissions reductions), but pollute more, especially NOx and PM (therefore are worse for air quality). Certain areas of the world (most notably Europe and countries which have followed Europe's precedent) have promoted diesels for the former reason by subsidizing the cost of diesel fuel and setting higher emission limits for diesel vehicles as compared with gasoline vehicles.

As diesel engine technology and emissions control systems improve, though, there is a growing call to eliminate any special policy treatment afforded to diesels, and instead adopt "technology neutral" environmental standards. (Note: the US and Japan's technology neutral standards are one reason diesel passenger vehicles have not had large penetration in those markets.)

Indeed, Dr. Bandivadekar's conclusion states:
Diesels don't have to be the problem...

The trade-off between air pollution and GHG reduction is artificial -- solution lies in strict, technology-neutral emission standards
But there are two additional key points that Dr. Bandivadekar makes that I want to feature.

The first is that low sulfur diesel fuel is required if advanced diesel emission control systems are to be installed on vehicles. His presentation features an excellent slide showing graphically the PM reduction potential vs. diesel fuel sulfur content:

As standards become more and more stringent, it is critical that fuels and vehicles be treated as a system, especially with regard to sulfur content. Unfortunately, however, many Asian nations still have extremely high sulfur content in their fuels:

This high sulfur content in many areas, including China outside of Beijing (this point to be expanded on in another post), is a major limiting factor to the introduction of cleanest technology diesel vehicles.

Another fascinating point that Dr. Bandivadekar raised is that greenhouse gas emissions from diesel vehicles are more than just CO2. Incomplete diesel combustion also results in the emission of "black carbon," another powerful contributor to global warming. When considering total greenhouse gas emissions, diesels only have an advantage over gasoline when black carbon emissions are controlled:

(In the above slide, "DPF" refers to "diesel particulate filter," an emissions control device that requires low sulfur fuel to operate properly.)

Therefore, the need for immediate implementation of low sulfur diesel fuel and advanced diesel emission control technology is supported from both air pollution and greenhouse gas reduction perspectives.

Lastly, I'm posting up one of Dr. Bandivadekar's first slides, the ICCT's excellent Bellagio Principles:

highlights from BAQ2008 - Chris Cherry and e-bikes

Electric bikes (e-bikes) may not be on the tip of the sustainable transportation community's tongue yet, but I think they should be, and in this post I'll explain why.

Dr. Chris Cherry of UT Knoxville is a (the?) leading international expert on e-bike development in China. His BAQ2008 presentation, "Environmental Impacts of E-bikes in China (and Beyond)," did an excellent job framing the e-bike discussion and current status.

First, take a look at this graph of recent e-bike production in China:

2007 e-bike production in China was over 20 million units, two and a half times more than motor vehicles. Anyone who has traveled regularly to China recently can attest to the reality that e-bikes are proliferating like crazy in Chinese cities. The sheer magnitude of these numbers (and the rapid rate of increase) demands that we investigate the energy, environmental, and social impacts of e-bikes.

Regarding the energy and environmental impacts, here is an incredible table Dr. Cherry developed on per passenger-km emission factors of various different transportation modes in China:

The values in the table are colored by impact. As expected, of the modes compared here, bicycling is the only one that receives "greens" across the board, while cars and motorcycles are generally "red" for highest impact. E-bikes, on the other hand, are competitive with buses for environmental impact for most pollutants except lead. (The extremely high lead emissions result from the e-bike batteries, which are comparable to car batteries; this makes it absolutely critical that lead pollution from increased e-bike production and use be controlled with lead acid battery production management and recycling programs.)


In my opinion, e-bikes should be given high priority as an urban sustainable transportation solution. E-bikes provide much greater urban mobility than buses, with comparable environmental impact, but result in significantly less air pollution and greenhouse gas emissions than cars or motorcycles.

However, e-bike development (and modal shift) should be carefully managed and understood. Direct modal shift from bikes to e-bikes clearly results in a net negative environmental impact, while the net environmental impact of modal shift from buses to e-bikes is unclear. Exploring this question, another slide of Dr. Cherry's presentation shows the results of mode choice surveying in Kunming:

The fact that most respondents chose an e-bike over a bus or standard bicycle may indicate that the e-bike proliferation has had a net negative environmental impact in Kunming.

That having been said, though, the primary, future environmental challenge in the transportation sector in China is controlling the impacts of a rapidly motorizing population. Therefore, the proliferation of e-bikes should be considered both in the context of current modal shift (e.g. what transportation mode would you choose today if not an e-bike) as well as the context of future behavior and mode choice. For example:

- How has the use of an e-bike transformed a customer's perceptions of the future need and use of a motorized vehicle?
- Has the owning of an e-bike delayed the inevitable purchase of a private car?
- Even if a car is purchased, what trips are the e-bikes still used for?

Most of all, whether you are for or against e-bikes, due to the massive growth in their production, at least two things are clear:

1) There is much more research to be done (modal share, lead pollution, safety, impact on regular bikes);
2) It is time for the sustainable transportation community to expand greatly the discussion of e-bikes and their impacts. (I told Dr. Cherry after his talk that at BAQ2010 there should be a whole panel on e-bikes, not just one presentation!)

Thursday, November 27, 2008

highlights from BAQ2008 - IEA

As mentioned in my last post, I'd like to feature some highlights from the BAQ2008 conference earlier this month in Bangkok. I haven't had a chance to go through even nearly all of the presentations, but there are some key slides / conclusions that I either remember from attending or found while browsing the files online that I'd like to post up here. Some of these will be a little out of context, but in all cases I will post the link to the original presentation for further info.

First, I'd like to post highlights from presentations I heard from Lew Fulton and Pierpaulo Cazzola of the IEA, based on energy demand projection research that went into the World Energy Outlook and Energy Technology Perspectives. (Side note: the just-released WEO 2008 Executive Summary is a must read.)

To start with, here are a couple of great slides from Mr. Fulton's presentation, "Transport, Energy, and CO2 in Asia: Where are We Going and How Do We Change It?":

The above slide shows IEA projections of global car stock by region (y-axis is in millions). Note the exploding dominance of China, especially after 2015-2020. This graph highlights both the incredible challenge we face to limit the energy and environmental impacts of vehicles worldwide, as well as the critical importance of guiding the inevitable growth of vehicles in the developing world in as sustainable a direction as possible.

On energy consumption and greenhouse gas emissions, Mr. Fulton proposed that it is both economically and technologically reasonable to target a 50% reduction in global light duty vehicle energy intensity by 2030. This loosely means reducing average car energy consumption from approximately 8 to 4 l/100-km. Note that some vehicles, such as the Prius, already achieve a fuel economy in this range.

However, current policies are not even close to guiding the vehicle fleet to this target. The following slide shows baseline vehicle fuel economy projections to 2050, taking into account all current legislation:

There is clearly a gap between what legislators (and the vehicle industry) are targeting, and what is currently possible (and required to meet necessary global GHG reductions).

Looking out to 2050, the IEA proposes that the majority of CO2 emissions savings from the transportation sector will come from improvements to conventional gasoline and diesel engines and traditional hybridization. This was surprising to me, as I expected electric vehicles and plug-in hybrids to play a bigger role. Additional savings are projected to come from some combination of electric vehicles and fuel cell vehicles, but the extent of those savings will depend on future technology improvements:

Fortunately, in the case of conventional engine improvements and traditional hybridization, pricing (in theory) shouldn't be the issue, as the fuel savings are on par with the additional technology cost for these vehicles:

Lastly, I'm posting up the conclusion slide from a talk with some overlapping content given by Mr. Cazzola called, "Fuel Economy as a Means to Avoid Future Greenhouse Gas Emissions from Transport":

The conclusion about monitoring increases in weight and power is critical, and something I will address in another post.

Tuesday, November 18, 2008


It's been a busy November for me so far, mostly due to tons of meetings and conferences. Most recently, I spent the past week down in Bangkok for the Better Air Quality 2008 (BAQ2008) conference.

All in all, the conference (actually my whole trip to Thailand in general) was just incredible - one of the best conferences I've ever attended. I had hoped to blog about the conference while down there, but internet access was sporadic for me, plus I was pretty engaged with meetings / discussions / panels for the entire time.

Over the next week, I will try to post up highlights from some of the presentations. In the meantime, I want to publicize the program, from which you can download most of the presentations. If you want to become an overnight expert on air quality in Asian mega-cities (plus a myriad of related issues like transport demand management, urban planning, health effects, links to fuel economy and GHG emissions, role of technology) these presentations are a fantastic place to start.

Before expanding on individual panels and presentations, though, I want to sing the praises for a moment of the Clean Air Initiative for Asian Cities (CAI-Asia). I was somewhat familiar with the group before, especially their excellent work summarizing Beijing Olympic air quality data, but it wasn't until this conference that I gained such tremendous respect for their dedication, organization, impact, and spirit. In just a few years, CAI-Asia has become the leading voice promoting partnerships and the sharing of air quality improvement experience throughout developing Asia. The incredible breadth and depth of this conference are testaments to the way they have catalyzed governments, NGOs, academics, and the private sector to work together towards the common goal of improving air quality in all cities.

Plus, I have to give them credit just for being so much fun...and recognizing that conferences are so much better when they are punctuated with singing, jokes, props, inspirational music, and the occasional strobe light...

Before signing off, I also wanted to mention that, earlier this month, I attended the very good 4th Regional Air Quality Management Conference from 11/6-7. Fulbright scholar Scott Moore has a good summary of the first day up on his great new blog, China Greenspace. As time permits, I will try to post up some comments on the second day, especially the transportation panel.

Monday, October 27, 2008

more on the datacenter

The Ministry of Environmental Protection's old air quality site hasn't been updated since 10/19, leading me to believe that the new online datacenter is here to stay. I finally had a chance to look through it in some depth today, and discovered some cool features. Unfortunately, the site is only in Chinese right now, but I'll keep checking and report back if an English version comes online. Also, it only works in Internet Explorer (not Firefox) on my computer, and even then still gives some weird scripting error messages.

In any case, here is a screen capture of the main interface:

The home page shows the Air Pollution Index (API) for 86 major cities in China, along with a pie chart displaying fractions of cities meeting various air quality grades. (In the screen shot above, 25 cities have "excellent" (优) air quality while 59 have "good" (良).) The bar graph below shows the 10 best API ratings across China each day. Congrats to Beijing for being 6th yesterday! The air quality data for the cities auto-scrolls on the home page; the complete list is presented here.

Besides additional air quality info (which I will discuss in detail below), the site features:

- Weekly water quality monitoring info for major river basins in China (全国主要流域重点断面水质自动监测周报), including some pretty detailed water quality analysis. (I'm no water expert, but from glancing through the data it seems both extensive and depressing.);
- A list of nature reserves in China (全国自然保护区名录);
- A list of companies in China that have received certification for environmental labeling (环境标志产品认证), though to be honest I'm not sure what this is used for;
- A search engine for environment-related scientific standards (科技标准查询), including links to the original documents;
- Some detailed info on solid waste management in China (限制类固体废物进口 and 自动类固体废物进口.)

My mouse goes directly to the air quality data, though, so let's explore that further...

First of all, as I mentioned in my last post, clicking on each city brings up a city-specific page, such as this one for Beijing:

At the top of this page, you can query past API data for any city you choose. In the results of the daily query, there is at least one new feature that was not previously available, and that is the presenting of the forecasted high and low API's for each day in parallel with the actual API. (Those in Beijing will remember last Friday's crazy winds; that day's actual API of 14 was a welcome, far cry from the predictions of 51-71!) There is also a graph of the last 30 days of API's.

Besides the city-specific sites, the following pages are available:

- A database of past air quality forecasts for each city (重点城市空气质量预报);
- An air quality analysis page (重点城市空气质量分析). There is some really cool stuff on this page - including the ability to rank and compare different cities in China against each other - and as such I think it deserves its own post. Therefore, rather than write more about it now, I'm going to save further explanation for another, more in-depth post about that page specifically. Also:

a) I can't imagine there are all that many people who got this far in this post anyway;
b) For those who did get this far, I want to make sure you have an excuse to come back to this blog; and,
c) It's time for me to leave the office...

Monday, October 20, 2008

I just noticed today a new feature on the website of the Ministry of Environmental Protection:

My browser is giving me some errors loading the pages, so it seems they are still doing some debugging, but so far it seems interesting. The pie chart above displays fraction of Chinese cities meeting different air quality levels today.

There are also links to city specific sites (e.g. Beijing) that automatically display a graph of the last 30 days of API data for each city:

(Note the 10/18 pollution spike I mentioned in my last post).

Historical API data is also now hosted on the new site, here: (The use of the term "test run" in the URL leads me to believe this is temporary, but we'll see; in any case the old API site has not yet been updated today so this is the only source of current data for now.)

pollution increases after the olympics

We are now one month past the end of the temporary air pollution reduction policies put in place for the Olympics and Paralympics. As expected, pollution levels have gone up. But how much? Using PM10 concentrations as an indicator, I estimate that the air quality in Beijing for the past month has been around 24% worse than it was during the two-month Olympic period. The pollution has actually been worse this past month than it was during the same period in 2007, though still significantly better than the same period in 2006:

It should be noted, though, that the averages over this past month are slightly skewed by the extreme pollution of this past Saturday (October 18th), when the API shot up to 174 (PM10 concentration 298 ug/m^3). This was the first day with an API above 150 since June.

Saturday's brutal - but short-lived - high pollution event raised a question in my mind that I'm not sure the answer to. From a health perspective, should we worry more about these short-lived extreme pollution spikes or long-term elevated baseline levels? For PM10 specifically, the WHO gives both daily and annual targets (50 and 20 ug/m^3, respectively). Granted, Beijing's air quality regularly exceeds both, but which is likely to cause more damage?

Lastly, it should be noted about the above table that I have done a direct conversion from API to PM10 concentration using the formulas at the bottom of this post, although this is an imperfect system because China does not list the primary pollutant for APIs below 50. Given the fact that PM10 is almost always the primary pollutant when the API is above 50, I think it's a reasonable approximation.

Tuesday, October 14, 2008

new vehicle restriction policy in beijing

I know, I'm a little late to the party on writing about this, so apologies for that.

As of yesterday, a new policy is in effect in Beijing to keep 800,000 cars off the roads every day. Though not nearly as far-reaching as the odd/even car ban implemented during the Olympics, the basic concept is the same: forbid certain cars from driving inside Beijing's fifth ring road depending on the last digit of their license plates. According to this policy, vehicles whose license plate numbers end in 1 and 6 may not drive on Mondays, 2 and 7 on Tuesdays, 3 and 8 on Wednesdays, 4 and 9 on Thursdays, and 5 and 0 on Fridays (though supposedly the prohibited driving days will change each month). There are no restrictions on the weekends. Additionally, the government has supposedly eliminated 30% of government cars, though the details on how are a bit hazy.

I'm curious to see what the results of this policy will be, both from a pollution perspective and a congestion perspective. My initial reaction on the former is that it won't have a huge effect, largely because cars are not the largest source of pollution in Beijing anyway. I wonder, then, if the ban is somewhat symbolic, a response to the loud public calls for the government to do something to signify a clear commitment not to let the pollution return to pre-Olympic levels.

Or maybe we are just seeing one step in a broad, coordinated series of policies designed to ween car-addicted Beijingers back to transit, bikes, and walking...

More info:

problems with the "blue sky day" metric

Late last month, consultant Steven Q. Andrews published an excellent report with detailed analysis of the publicly reported daily API data for Beijing. His key findings, which were first published as an op-ed in the Wall Street Journal (and subsequently covered by the New York Times, Time, and others), are as follows (quoted from the report's abstract):
Here I show that reported improvements in air quality [in Bejiing] for 2006–2007 over 2002 levels can be attributed to (a) a shift in reported daily PM10 concentrations from just above to just below the national standard, and (b) a shift of monitoring stations in 2006 to less polluted areas.
Many people, including Mr. Andrews, have been asking me my opinion on the findings of the report. Here, I will try to summarize what I consider to be the most impressive and surprising results, while also commenting on what the report's results do - and don't - show.

Summary: Statistical analysis of reported API frequency shows clear data biasing to reach Blue Sky Day targets, and, as such, I think effectively invalidates the use of annual number of Blue Sky Days as an air quality measure. This is an extremely impressive finding that I hope the Chinese government will respond to appropriately, both by reconsidering the use of the Blue Sky Day metric altogether and investigating how such bias was introduced and eliminating it in the future.

However, I caution against using this finding alone to make broader, sweeping assumptions about Beijing's air quality changes over the last five or ten years. Specifically, Mr. Andrews' report should not be used as proof that any and all recent improvements in air quality in Beijing have been simply the result of "gaming the numbers" as opposed to actual improvements. While Mr. Andrews' results regarding numbers of Blue Sky Days are dramatic, his analysis of pollutant concentrations in recent years focuses on only one pollutant, PM10, and shows concerning, but not dramatic, discrepancies to the officially reported data. Additionally, when discussing PM10, it should be noted that controlling concentrations of particulate is well known to be one of the biggest air quality challenges faced by Beijing, and that trends of PM10 concentration should not necessarily be equated with trends of other pollutants or even trends of overall air quality.

Finally, while I think Mr. Andrews' analysis normalizing air quality data across multiple years by accounting for the moving of monitoring stations is excellent, correct, and appropriate, I do not think it proves deliberate deceit about air quality (as the Blue Sky Day biasing does).


Blue Sky Day Data Biasing

First of all, to me, the most impressive graph in the report is this one, showing the dramatically higher frequency of reported PM10 concentration just below the Blue Sky Day cut-off than just above (Figure 2 from Mr. Andrews' report):

Equally impressive is this statement from the report:
While 52% of the days with a city API between 96 and 105 (PM10 = 142–160 μg m−3) were reported as ‘Blue Sky’ days in 2001, 98% of the days in this range were ‘Blue Sky’ days in 2006, and 93% of days in the range were ‘Blue Sky’ days in 2007.
This seems to show, unequivocally, that there is bias in the reported data around the Blue Sky Day cut-off point. From this data, it appears that the use of the number of Blue Sky Days metric is not reliable as an indicator of Beijing's air quality improvement. Therefore, I will stop using it as such and will edit a previous post on this blog that references it. I would hope that, in time, Beijing will recognize this clear bias and take steps towards identifying how it is introduced and preventing it in the future. At the same time, detailed investigations into potential biasing of other pollutant data should also be conducted (though it seems less likely that such biasing would have occurred, given the fact that the biasing appears to be related to meeting Blue Sky Day targets, for which PM10 is usually the limiting factor).

Moving of Monitoring Stations

The second issue Mr. Andrews raises is the moving of monitoring stations. While I find his analysis here to be fascinating and correct, I'm not convinced that his results prove that the moving of the monitoring stations was driven by the desire to lower artificially air pollution levels by measuring in less polluted areas. He mentions that the new monitoring regulations put into effect in 2006 included "new specifications...regarding the minimum distance from roadways that air pollution should be monitored." I don't know enough about international monitoring to know if perhaps these new standards were designed simply to bring China's monitoring better in line with international standards? Whatever the case, Mr. Andrews' point that different measuring systems were used is valid:
It has been widely reported that the number of ‘Blue Sky’ days in Beijing increased from 100 in 1998 to 246 in 2007, but these reported trends encompass a period during which air quality was evaluated in three different ways: (1) 1998– 1999, based on the 1996 Chinese national ambient air quality standards (2) 2000–2005, based on the 2000 revisions of the Chinese national ambient air quality standards and using the 1984–2005 monitoring station locations (3) 2006–2007, based on the 2000 revisions of the Chinese national ambient air quality standard and using the 2006–2007 monitoring station locations.
Ideally, officially reported data in the future should note the change in monitoring methodology on graphs showing data from both periods.

Impacts on Pollutant Concentration

As Mr. Andrews points out in the report, the Blue Sky Day metric is a "policy-relevant metric," and, "an effective communication facilitate greater public understanding." In other words, it is not a scientific metric, insofar as the cut-off point of API = 100 is rather arbitrary. Evaluating the effect of the aforementioned bias and monitoring station location change on reported vs. actual air quality requires analyzing pollutant concentrations.

Using a methodology to eliminate the reporting bias and normalize across similar reporting stations, Mr. Andrews' ran a new concentration analysis for PM10 and generated the following results:
In 2006, an annual average PM10 concentration of 161 μg m−3 was reported, however, if the monitoring station used from 1984 to 2005 continued to be used in 2006, the concentration would be ∼167 μg m−3—an average concentration ∼6 μg m−3 higher than reported. In 2007, an annual average PM10 concentration of 149 μg m−3 was reported, however, if the original monitoring stations continued to be used in 2007, the concentration would be ∼161 μg m−3—an average concentration of ∼12 μg m−3 higher than reported.
Stated differently, he concludes that Beijing's 2006 and 2007 reported values for PM10 were about 3.6% and 7.5% lower, respectively, than they would have been without data biasing or moving of monitoring stations. While this is concerning, the results are not nearly as dramatic as the difference in Blue Sky Days, as shown in Mr. Andrews' report (Figure 3 from the report):

In the above graph, note that the difference in Blue Sky Days (shown as columns) is much greater than the difference in PM10 concentration (shown as red lines). Note also that while the trending on Blue Sky Days changes dramatically based on the new analysis (increasing 2001-2005, decreasing 2005-2007), the trending on PM10 does not show a large change under the new analysis.


As I mentioned earlier, Mr. Andrews' result regarding the biasing of annual numbers of Blue Sky Days is powerful and dramatic. However, I'm not sure the result regarding 2006-2007 concentrations of PM10 is as dramatic, especially given the fact that PM10 has notoriously been one of the most difficult pollutants for Beijing to control. The Beijing EPB's own data show a 2007 PM10 concentration of 149 um/m3, higher than 2003 and 2005. While adjusting the concentration data according to Mr. Andrews' analysis may be important, doing so does not qualitatively change the 2001-2007 PM10 trends in Beijing.

Mr. Andrews concludes his report:
Although nine continuous years of air quality improvement has been reported in Beijing between 1998 and 2007, my analysis finds that these improvements, as indicated by the annual number of ‘Blue Sky’ days, are due to irregularities in the monitoring and reporting of air quality and not to less polluted air. Reported variations in air quality that occur as a result of changes in monitoring station locations or air quality standards, should be considered as inconsistencies in the metrics and not as actual changes in air quality.
While I agree with his analysis showing data biasing in the numbers of annual Blue Sky Days over the past few years, I think it is critical to clarify that such biasing does not mean that there was no improvement whatsoever in Beijing air quality over the last decade.

Friday, September 26, 2008

no pollution spike yet - API of 17!

Sunset snapshot from a friend's window

The buzz among Beijingers (at least among my friends) today is how clean the air felt last night and today. And it turns out they're right. The API from noon yesterday to noon today was a lung-clearing 17. This is tied for the lowest on record (going back to June, 2000).

There have been only four days in the last eight years with an API of 17. They were 10/12/2003, 10/1/2004, and 8/15/2008, which I blogged about.

Update 10/20/08: In reviewing data today on MEP's new air pollution database website, I unexpectedly discovered the unbelievably low API of 12 listed for 9/23/08. That day currently ranks as the lowest API going back to June, 2000.

The pollution spike I feared occurring after 9/20 hasn't happened yet anyway...

thoughts on runaway climate change

This morning on the subway, I was so deep in thought about climate change that I missed my stop. Specifically, I can't stop thinking about a Letterman video I watched a couple of days ago and a graph I saw this morning.

First, the Letterman video. The basic message, presented with classic Letterman deadpanning, is, "We're Doomed."

While I appreciate the attention given to global climate change, and I do enjoy the humor, I generally prefer a more optimistic approach to problem solving...

...But then I saw this graph, from the Global Carbon Project, showing the updated trend of global carbon emissions from fossil fuels:

(As reported on Climate Progress and Climate Feedback.)

Update: the data in this graph just made the front page of CNN: Carbon Dioxide Output Jumps to Record Level.

The data in this graph is terrifying, and it's not just because the trend is going the wrong way (increasing as opposed to decreasing). It's terrifying because actual emissions are outpacing assumed emissions even under the IPCC's "worst case scenario" (actual growth has been 3.5% per year since 2000 as opposed to projected 2.7%). Even without these "extra" emissions, though, the effects of climate change are already being seen much earlier than anticipated by climate models (example: the faster than expected melting of Arctic sea ice). This is principally because the climate models underestimate the effects of certain feedback mechanisms that accelerate warming. A classic example is the fact that as Arctic sea ice melts, it reveals more dark ocean, which absorbs solar radiation more than reflective white ice; this absorption causes the earth to warm faster, which melts more ice, revealing more dark ocean, further perpetuating the cycle.

So then back to Letterman's "It's too late" argument. Though the optimist in me rejects the conclusion, there are days (like today) in which the cynical side of me looks at the data, recognizes how little progress we have made in the fight against global climate change, considers the challenges ahead towards even just slowing the growth in greenhouse gas emissions (not to mention reducing them!), and thinks, How are ever going to do this?

Lastly, the following animation, "Wake Up, Freak Out - then Get a Grip," does a good job describing the "tipping point" of the earth's climate system, beyond which catastrophic changes are inevitable:

(Note: I think the second half of the video is a little too apocalyptic, which I think undermines his conclusion that it's not too late, but nonetheless the first half is quite good.)

Saturday, September 20, 2008

final day of temporary air quality measures

Prior to the Games, a major question asked on this blog and elsewhere was, "Will Beijing's efforts to control the air quality work?" (Some analysts even boldly predicted that they wouldn't.) And now, here we are, on September 20th, 2008 - the final day of the temporary environmental policies implemented by the Beijing government to control air quality during the Olympic and Paralympic period - with a resounding "yes" answer to that question.

Through the banning of over half the cars on the roads, the temporary closing of factories, the shutting down of construction in the city, and a little luck from the weather (on second thought, not luck), Beijing managed over the past two months to reduce air pollution by around 50% (analysis at the bottom of this post) and yield the cleanest air the city has seen in ten years.

Let's look one last time at the graph of daily Air Pollution Index during the Olympic period:

And some averages:

Average API, Two-month Olympic period, 7/20/08 - 9/20/08: 62
Average API, Olympics, 8/8/08 - 8/24/08: 49
Average API, Paralympics, 9/6/08 - 9/17/08: 59

According to my analysis, these numbers are comparable to the air quality during the 1984 Los Angeles Olympics (in that previous post, I estimated that the air quality during the Los Angeles Olympics would have rated as a Chinese API of 59).

To get a better sense of just how much better Beijing's air actually was from 7/20 - 9/20 of this year, it makes sense to convert the numbers from API back into particulate matter concentration (explanation at bottom of this post), and compare those numbers against some past data.

The following table shows average API and PM10 concentrations for some selected time periods over the past three years (2006 and 2007 PM10 data from Beijing EPB environmental annual reports):

Update 10/20/08: Found a minor mistake in the first version of the PM10 data I showed below; fixed now.

From this data, we can calculate that, according to PM10 concentrations, Beijing's air during the two-month Olympic period was:

-- 44% less polluted than the first half of 2008;
-- 40% less polluted than the same period in 2007;
-- 47% less polluted than all of 2007;
-- 51% less polluted than all of 2006.

These numbers are comparable to the Beijing EPB's statement that concentrations of major pollutants were cut by 45% during the month of August.

Lastly, for a different perspective on the impact of the temporary air quality control policies, I wanted to show API data over a much longer time period. The following graph shows daily API readings from the beginning of 2006 to today:

I find this graph fascinating (granted, I'm an engineer). Two key observations jump out at me: first, the average API during the Olympic period is clearly lower than any previous periods of comparable length. Second, perhaps more interestingly, the extreme variability has been reduced tremendously; specifically, Beijing succeeded in prevented any severe spikes in air pollution that were so common in previous periods.

Which, of course, leaves me wondering: how long before we see another one of those dreaded spikes?

Tuesday, September 9, 2008

paralympics air quality update - 9/6 API missing

The last time I presented daily API data was on August 24th, the final day of the Olympics. With the Paralympics now underway, I figure it's time to take another detailed look at the air quality status.

Since 7/20, the day the odd/even car ban and other temporary air quality control policies went into effect, the graph of daily API values is as follows:

A couple of things worth noting:

1) Though the API was below the target cut-off of 100 for the entire Olympic period, between the Olympics and Paralympics we saw one day, 8/29, in which the API shot up to 110.

2) The API data for 9/6 is conspicuously missing. (As always, my source for API data is the query at the bottom of MEP's air quality page.) Does anyone out there have this data point, perhaps from the Beijing EPB? I seem to remember that day - the day of the Paralympic opening ceremony - being particularly hazy, but I didn't check the data then. Missing data is always concerning, of course, but especially here.

Still, though, the results for overall air quality since 7/20 are remarkable. The average API from 7/20-9/9 of this year is 63; during the same period last year the average was 89.

Lastly, the weather has seemed quite strange recently here in Beijing; over the last few days I've seen two of the heaviest thunderstorms I can remember in China. Anyone agree?

Monday, September 8, 2008

paralympics underway!

Last Saturday night, the Paralympics began here in Beijing with a gorgeous and moving opening ceremony. Apparently you can watch it online here, though I can't seem to get the site to work from within China.

One of the most powerful moments of the ceremony was the lighting of the torch (which, by the way, it's nice to see blazing again!). Three-time high jump gold medalist Hou Bin hoisted himself, his wheelchair, and the torch by pulley from the floor of the stadium all the way up to the base of the cauldron.

It took him over three minutes to reach the top, and you could clearly see the strain on his face as he struggled to continue, even pausing occasionally to rest. It was an incredibly powerful symbol both of the struggle faced by so many people with disabilities as well as the ability to succeed and overcome those struggles through perseverance.

Here's the video on YouTube:

Photo credits: 1) Reuters/David Gray via NYT; 2) Xinhua.

Friday, September 5, 2008


A couple of quick disclaimers regarding information on this blog:

1) The opinions I share on this blog are mine alone, and do not represent those of my past or current employer (who I have not named here).

2) The analysis I present on this blog has not been peer-reviewed (unless otherwise noted), and should generally be considered back-of-the-envelope data explorations intended to promote discussion, not rigorous scientific analysis. I will, however, cite original data sources and explain assumptions and reasoning as much as possible, in case others want to verify my analysis and/or take it further.

Please feel free to link to or cite information on this blog, but if you do I ask that you stay mindful of the above two points.

If you have any questions, please contact me at livefrombeijing at gmail dot com.

Thursday, September 4, 2008

what will happen on september 21st?

In my last post, I described how international media and conversation about Beijing's air largely went silent starting around the second week of the Olympics. However, local conversation here in Beijing has been anything but quiet. If anything, just as foreigners began to lose interest in the seeming non-story of Beijing's lack of air pollution, the local buzz about the improved air quality was just starting to gain momentum.

First, a little background: in August, 2008, Beijing had the cleanest air in 10 years, with the "density of major pollutants cut by 45%" during the month. The data is in and the results (and the air) are clear - the temporary measures to reduce air pollution in Beijing worked.

I remember when the temporary measures were announced back in June, I had mixed reactions. While on the one hand I was personally excited for two months of breathing clean air and riding my bike on gridlock-free streets, as an environmental professional I was disappointed that such temporary policies were needed in the first place. Clearly, the preferred solution would have been the implementation of stringent, permanent air pollution control policies that would have ensured sustainable, Olympics-approved air quality without the need for stop-gap measures. As I contemplated the potential results of the temporary policies, I asked many of my friends and colleagues what they thought would happen on September 21st (the first day after the temporary bans end). At that time (late June), virtually everyone's unanimous response was that Beijing would simply revert back to the same old smog that we had all become used to. In other words, most people I asked thought there would be no long term impacts of the temporary policies.

But I think those of us who have lived in non-polluted cities (please allow me to use the phrase "seen the light," meaning lived in a place where you can't look directly at the sun without burning your eyes, as you often can in Beijing) always held out one great hope: that Beijing's residents and politicians would be inspired; that they would experience life with crystal clear blue skies every day and wouldn't want to go back.

And over the past week or two in Beijing, the most amazing thing has happened: it seems that hope is being fulfilled. Media articles, blog posts, and chat forum polls are filled with discussion on how to keep the air quality this good, with much specific debate on whether or not the odd/even car ban should be made permanent.
I'm happy - ecstatic - that these discussions are happening, and that the citizens of Beijing are taking direct interest in and action on air quality. I am even more ecstatic that, so far, the government is open to the opinions and suggestions of the people.

Regarding the permanence of the odd/even car ban, I think it is natural and expected that this should be the focus of the discussion, as this is the single temporary policy that has affected individual citizens the most. However, while I hate to inject any negativity into what I consider to be a wonderful development of citizen environmental activism in China, I feel I must point out that a permanent odd/even car ban may not be the best long term strategy to maintain the air quality we saw over the month of August. For one thing, it is unclear right now how much the air quality improvement can be attributed to the vehicle reduction (as opposed to the factory closures and construction halting). For another thing, as was pointed out on Time's China blog, such a policy could end up having the opposite desired effect, depending on the resulting purchase and use of second cars.

To summarize: hurray for the people in Beijing for demanding that this air quality continue, for the Chinese media for publishing their demands, and for the Chinese government for listening. But let's make sure this energy and drive are directed in the right directions. And what are those right directions? Well, Alex Pasternack has a great start up on Treehugger: 10 Ways Beijing (and Other Cities) Can Keep Its Skies Blue and Road Gridlock-Free.

olympics round-up: impressions of air quality

Photo by Lila Buckley

In the weeks leading up to the Olympics, Beijing's air quality was constantly in the news; questions about whether Beijing would meet its air quality targets, whether events would need to be postponed, and whether the pollution would affect athletes' performances seemed to be the constant refrain of Western conversations about the upcoming Games. In early July, the New York Times cited air quality as one of two primary remaining uncertainties about the preparations.

As the Games approached, these concerns seemed to be entirely validated. Two weeks prior to the Games, Beijing's air pollution exceeded the Olympic standard for four straight days; even the last few days before the opening ceremony were dangerously close to the limit.

Over the first few days of the Games, though, as the API bounced up and down, we began to see mixed reviews about the quality and the impacts. At that time, I predicted a stalemate, imagining that the end result would be the Chinese claiming success with regard to air quality and foreigners grudging that it still wasn't good enough. (Interesting side note here: as I have indicated, the average API during the Olympics was 49; before the Games started, beijingairblog specifically quoted an expert stating that an API of 50 was still "very unhealthy," claiming that only an average API of 25 would be "acceptable for Olympic competition.")

But then, by the second week of the Olympics, a funny - and unexpected - thing happened. The stalemate I predicted never really happened, because Beijing's air quality critics backed down. By August 13th, the New York Times called it "the great air pollution scare," dubbing it "the Y2K computer scare — a nonevent." On the 18th, danwei titled a blog post "Pollution wussies go quiet." Later, DH commented on my blog:
Yo Vance, Gotta tell you that after the start of the games I heard almost NOTHING about air quality from any of the major news sources. Seems like maybe they just decided it wasn't a story anymore. Plus none of the athletes wore those Batman-style gasmasks so there may have been no real "story" to cover...
By the end of the Games, air pollution was a non-issue, eclipsed by so many other stories of the Olympics. Air quality, which seemed so dominant a concern before the Games happened, was barely even mentioned in many of the summary write-ups of the Games that appeared shortly after the closing ceremony. (For example here, here, here, and here.)

However, while Beijing's air quality may no longer be making many headlines abroad, the exact opposite is true here in China. But this is a topic for a separate post...

Sunday, August 24, 2008

end of the games

First of all, apologies for the lack of posting this week; I've been busy watching as many events as I can while simultaneously struggling through a wicked cold. With the end of the Games finally upon us, though, I thought I'd fire off some quick numbers on how Beijing did:

First of all, Beijing met its goal of keeping the API below 100 during the Games. Here is the data for the 17 days 8/8/08-8/24/08:

Second, it seems the temporary policies (+ regular rains throughout the Games) worked; let's take a look at some average numbers for comparison:

Average Beijing API during the Olympics, 8/8/08-8/24/08: 49
Average Beijing API since the car ban went into effect, 7/20/08-8/24/08: 64
2007 Yearly Average Beijing API: 101
Average Beijing API during Olympic period 2007, 8/8/07-8/24/07: 86
Average Beijing API during Olympic period 2006, 8/8/06-8/24/06: 76

The average API in Beijing during the 2008 Olympics was 43% lower than the average API in Beijing during the same period in 2007. I'd say that's a pretty dramatic improvement.

More analysis to come.

Saturday, August 16, 2008

beautiful in beijing

Yesterday was one of the most beautiful days I've ever seen in Beijing. And the data supports it: the API of 17 yesterday is tied for the lowest on record (going back to June, 2000). Here's the data since the car ban started on 7/20:

As of 8/13, the New York Times was already quoting athletes calling Beijing's pollution concerns "massive hype," and proposing, "it may seem that the great air pollution scare is becoming the equivalent of the Y2K computer scare — a nonevent."

While I appreciate the optimism, I'm not quite willing to go that far at this point; I am still tracking the data carefully and will reserve any sweeping "success" judgments until the end of the Games.

Still, though, I suppose if Beijing can survive the opening ceremony with an API of 94 and the two long distance cycling events at 78 and 82, then the odds are pretty good that we aren't going to see any other dramatically different impressions of the air quality than what we have seen already.

Wednesday, August 13, 2008

the rift on air quality during the Games

Regarding everyone's favorite Olympic environmental topic, air pollution, it seems like we've reached the stalemate I wondered about at the end of my very first post on this blog. Depending on who you ask, China should either be congratulated for meeting its air quality goals or chastised for allowing athletes to compete in such horrible pollution.

On the one hand, the constant refrain from both the IOC and the Chinese media is that the air poses no risk to the athletes. From Reuters:
The International Olympic Committee (IOC) had warned it might reschedule events if the air quality posed a threat, but on Sunday it said there were no problems.

"The readings that we were looking at indicated that we have no cause for concern at this stage," said IOC spokeswoman Giselle Davis.
On the other hand, we are still seeing many reports with detailed descriptions of how bad it is here. From The Oregonian:
Last weekend, when days were hot, humid and still, the smoggy haze hung thick as a wool blanket. In her blog, [distance runner Kara] Goucher wrote:

"I have to say that the pollution and smog in Beijing is much, much worse than I imagined. It's a bit eerie how the sun never comes out all day. If you are walking around the village and you look ahead, you can't see all of the buildings. The pollution creates a fog that clouds over everything. It is unimaginable. I am shocked by how bad it is."
CNN summarizes, "Despite official assurances that the air is safe for competition, athletes and fans have expressed concern over the thick smog covering the entire city."

However, not everyone is convinced that the air is all that bad. From the New York Times blog:
A handful of track and field athletes worked out on a rainy Sunday morning at the United States Olympic compound at Beijing Normal University, and most said they had not been bothered by the air quality in Beijing. They were adjusting to the humidity, but the pollution, they said, had not been an issue.
This rift - between those who find Beijing's air quality acceptable and those who find it intolerable - that has opened up over the past few weeks is fascinating to me. Perhaps most interesting is that fact that the debate seems to be playing out on so many levels: technical, medical, psychological, political, and more. (I hope to blog in more detail on this topic later.)

In any case, no matter which side you take, at least we finally have some idea of what the air quality is going to be like during the Games. Since 8/8, the API has been up and down. And yet, with the API not "down" enough to make all the foreigners happy and not "up" enough to exceed the Chinese cut-off of 100, the result? Stalemate.

Friday, August 8, 2008


Today is a day to forget about graphs and data and simply to enjoy the spirit, the hope, the optimism, the unity of the Olympics.

I just changed my cell phone ring tone to the Olympic theme music. Needless to say, I am really excited. It is a great day to be here in Beijing!

One World, One Dream!

Thursday, August 7, 2008

last day before the Games - API at 95

Today's API of 95 is not an encouraging last data point before the Games start tomorrow. I was just up at the Olympic Green and the air there is what my friend describes as "mashed potato air." Beijing API data since the car ban went into effect shown here:

No word yet on whether or not MEP will implement emergency pollution reduction measures. On the contrary, in some respects China doesn't seem all that worried, as evidenced by this article from Xinhua: "IOC: Beijing delivers on environmental promises."

Wednesday, August 6, 2008

los angeles 1984 olympic air quality

This is the second in a series of posts comparing Beijing's air quality to that of other Olympic host cities. Here, I explore the air quality of Los Angeles during the 1984 Games.

Summary: Lack of available data makes directly comparing the air quality during the Los Angeles Olympics to that of Beijing challenging. The only air quality data I could find for Los Angeles in 1984 are concentrations of ozone and Total Suspended Particles (TSP). Unfortunately, PM10 measurements did not begin in Los Angeles until 1988, and no ozone concentration data is available for Beijing.

Still, some rough comparisons may be made by examining LA's TSP data as well as PM10 data from 1988 on. Here, I conclude the following:

1) Beijing's 2007 annual average PM10 concentration (148 ug/m^3) was approximately twice as high as that in LA in 2007 (76 ug/m^3), and about 1.4 times higher than that in LA in 1988 (104 ug/m^3)
2) Since the car ban went into effect in Beijing on 7/20, the average PM10 concentration has been 111 ug/m^3, 7% higher than LA's 1988 average.
3) Using a rough estimate that PM10 in LA is about 55% of TSP, I estimate the average PM10 concentration in LA during the 1984 Olympics to be around 68 ug/m^3 (corresponding to a Chinese API of 59), more than double the concentration during the Atlanta Games.

Analysis: Again, let's start by examining data sources. The best data source I found was Air Quality Data Statistics from the California Air Resources Board. For an overview, I chose Air Quality Trend Summaries and queried PM10 for the South Coast Air Basin. Unfortunately, the earliest data available in this query is from 1988. Prior to 1988, it seems that the EPA only required the measurement of Total Suspended Particles (TSP), not PM10. The difference between TSP and PM10 is that TSP includes all particles of all sizes, whereas PM10 only includes particles smaller than 10 microns in size. The smaller particles are more damaging to human health because they penetrate deeper into the lungs.

Below is a graph of the available annual PM10 average data for the South Coast Air Basin and Beijing:

It is clear from this graph that Beijing's annual PM10 concentration is still significantly higher than that in Los Angeles, even looking all the way back to 1988.

But, as mentioned in my post on Atlanta, during the Olympics we care less about yearly averages and more about daily averages. And, indeed, the air quality in Beijing recently has been considerably better than the 2007 average. Specifically, the average PM10 concentration in Beijing since 7/20 has been 111 ug/m^3, just 7% higher than LA's 1988 average (104 ug/m^3).

Though PM10 data is not available for LA during the Olympics, it may be worth taking a look at the TSP data to see what we can learn. Summary data for the area is not available prior to 1988, but we can query individual monitoring stations going back to 1983. I chose to query a 10-week period in 1984 starting with July 1. Though there are 12 monitoring sites in Los Angeles, daily data only exists for two stations: Los Angeles - North Main St. and Azusa. This data is shown in the graph below:

During the Olympic period (7/28/84 - 8/12/84), the average TSP concentration at LA - North Main St. was 113 ug/m^3, while the average at Azusa was 136 ug/m^3. I will take an average of these two readings, 124 ug/m^3, as a rough estimate of the TSP concentration in LA during the 1984 Olympics.

Of course, the most obvious question then is: what percentage of the TSP is PM10? I'm not sure the best way to answer this, but I suppose it's reasonable to make a rough approximation by comparing TSP and PM10 data for a time period in which both are available. Towards this goal, I queried TSP and PM10 for the first available year - 1988 - for the Los Angeles - North Main St. station, and compared the TSP to PM10 results for all common data points throughout the year. The result is that on average, the PM10 concentration was 55% of the TSP concentration.

Applying this 55% factor to the Olympic TSP data described above yields an estimated PM10 concentration during the Los Angeles Olympics of around 68 ug/m^3, corresponding to a Chinese API of 59. This result is significantly lower than even the 1988 average, but is consistent with descriptions of considerably improved air quality in LA during the 1984 Games.

Conclusion: Though it is impossible to compare directly the air in Beijing with the air in Los Angeles during the 1984 Olympics, it is clear that, from the perspective of PM10, Beijing's average air is considerably more polluted than that in Los Angeles even in the late 1980's. During the 2008 Olympics, for Beijing's air to be considered equal quality to Los Angeles during the 1984 Olympics, Beijing's API during the Games should average 59 or below.