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Wednesday, November 23, 2011
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Demystifying China’s Controversial Air Quality Measurements

By Guest Author, Angel Hsu, PhD candidate, Yale School of Forestry and Environmental Studies

Beijing’s air quality dominated international headlines when discrepancies arose last month between official monitoring data and U.S. Embassy measurements.

Pictures of stifling haze and smog posted and circulated online by netizens depicted extreme pollution. The U.S. Embassy’s monitor indicated that the air quality was “hazardous” and “beyond index, but “the Chinese government’s official Air Pollution Index indicated that the air was only “slightly polluted.[1]

Why the inconsistency? To start, the U.S. Embassy’s monitor, which was originally put in place in 2008 to record air quality during the Olympics, measures finer particulate matter with a diameter of 2.5 micrometers or less (PM 2.5) and ozone. These particulates are more relevant for human health because of their ability to penetrate human lung tissue and lead to asthma, lung cancer, and cardiovascular disease. The Beijing measurements, however, don’t include these pollutants and instead take an average of measurements from monitoring stations from around the city. 

Many people are asking which measure is more accurate. This is a difficult question to answer because it’s almost like comparing apples and oranges. The two systems are measuring different pollutants, and the U.S. monitor is only looking at one point source compared with Beijing’s 27 monitoring stations. The accuracy the U.S. Embassy’s monitor – and how often the instruments are calibrated – is also unclear. Granted, Beijing’s system has its flaws, which the government has acknowledged and is working to improve. As a sign of good faith, the Beijing Environmental Protection Bureau announced that it would allow public tours of its air monitoring facilities to show that they aren’t trying to hide behind the data.

These efforts come in conjunction with several important policy developments regarding air quality in China.  Last month I wrote about new efforts to pilot PM 2.5 measurement in model environmental protection cities in China. Last week, the Chinese government announced new ambient air quality standards for PM 2.5 and ozone levels (link available in Chinese only). While still slightly below WHO recommendations, these new standards are a significant step in the right direction, particularly when diplomatic cables suggested that PM 2.5 data were deemed too politically sensitive to measure and report. These new standards will likely not take effect nationally until 2016; however, major cities like Beijing and Shanghai, which already measure PM 2.5 but do not publicly release the data, likely will roll them out sooner. Officials from the Ministry of Environmental Protection have already noted that there will likely be a binding national target for PM 2.5 in the next Five-Year Plan.

LinkAsia recently asked me to discuss Beijing’s controversial air quality data and some of the measures the government is taking to address citizen concerns over poor air quality. You can view the interview here: http://www.linktv.org/linkasia/linkasia2011111119/understanding-chinas-deadly-air.

 


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