Beijing Air (cont'd)06 Dec 2011
Following up a bit on my previous post on air pollution in Beijing, China, my brother forwarded me a link to some work conducted by Steven Q. Andrews on comparing particulate matter (PM) air pollution in China versus Europe and the US. China does not officially release fine PM measurements (PM2.5) and furthermore does not have an official standard for that metric. In the US, PM standards are generally focused on PM2.5 now as opposed to PM10 (which includes coarse thoracic particles). Apparently, China is proposing a standard for PM2.5 but it has not yet been implemented.
The main issue seems to be that China has a somewhat different opinion about what it means to be a “bad” pollution day. In the US, the daily average national ambient air quality standard for PM2.5 is 35 mcg/m^3, whereas the proposed standard in China is 75 mcg/m^3. The WHO recommends PM2.5 levels be below 25 mcg/m^3. In China, days under 35 would be considered “excellent” and days under 75 would be considered “good”.
It’s a bit difficult to understand what this means here because in the US we so rarely see days where the daily average is above 75 mcg/m^3. In fact, for the period 1999-2008, if you look across the entire PM2.5 monitoring network for the US, you see that 99% of days fell below the level of 75 mcg/m^3. So seeing a day like that would be quite a rare event indeed.
The Chinese government has consistently claimed that air pollution has improved over time. But Andrews notes
…these so-called improvements are due to irregularities in the monitoring and reporting of air quality – and not to less polluted air. Most importantly, the government changed monitoring station locations twice. In 2006, it shut down the two most polluted stations and then, in 2008, began monitoring outside the city, beyond the sixth ring road, which is 15 to 20 kilometres from Beijing’s centre.
Andrews has previously published on inconsistencies between Beijing’s claims of “blue sky days” and the actual monitoring of PM in a paper in Environmental Research Letters. That paper showed an unusually high number of measurements falling just below the cutoff for a “blue sky day”. The reason for this pattern is not clear but it raises questions about the quality of the official monitoring data.
China has a novel propagandistic approach to air pollution regulation, which is to separate the data from the interpretation. So a day that has PM2.5 levels at 75 mcg/m^3 is called “good” and as long as you have a lot of “good” or “excellent” days, then you are set. The problem is that you can call something a “blue sky day” or whatever you want, but people still have to suffer the real consequences of high PM days. It’s hard to “relabel” increased asthma attacks, irritated respiratory tracts, and myocardial infarctions.
As the China Daily recently wrote: “All of the residents in the city are aware of the poor air quality, so it does not make sense to conceal it for fear of criticism.”
Maybe the best way to conceal the air pollution is to actually get rid of it?