Thursday, January 17, 2013

Beijing Air Pollution off the Charts

Air pollution in Beijing is once more in the news. Last weekend the Air Quality index as measured by the PM2.5 monitoring station atop the US Embassy in Beijing surpassed 700 for 24 hours and the Chinese took a series of emergency response measures in Beijing Sunday to protect children and the old from the high levels of air pollution. The Beijing municipal government reported levels of 500 over the weekend, but the Chinese system does not report numbers beyond 500 which is the top of the official Air Quality scale. Nonetheless, the air quality had exceeded the standards of hazardous according to the U.S. Environmental Protection Agency. For comparison last month the U.S. Environmental Protection Agency announced the reduction in the fine particle pollution, PM2.5, average annual allowed level to 12 micrograms per cubic meter (ug/m3) or an AQI of 39. The 24-hr standard was recently revised to a level of 35 ug/m3 (an AQI of 99) and in truth not all cities in the United States currently meet that standard. Bakersfield, California with a population of about 350,000 has some of the worst air in the United States and does not quite meet that annual level, but their air quality numbers are a fraction of Beijing’s.  

PM2.5 particles can be either directly emitted or formed via atmospheric reactions. Primary particles are emitted from cars, trucks, and heavy equipment, as well as residential wood combustion, forest fires, and agricultural waste burning. The main components of secondary particulate matter are formed when pollutants like NOx and SO2 react in the atmosphere to form particles. These particles are emitted from coal fired power plants and other combustion engines. The increase in automobiles and coal fired power plants (not using the cleanest technology) has created this problem in Beijing. While particulates can travel great distances, this problem is the result of the expansion of the economy without the strict air pollution controls on their coal fired power plants and industry, which was within my lifetime the experience in our own cities.

So, as the Chinese spew more and more carbon dioxide into the earth’s atmosphere they are also spewing , pollutants and particulates which are most concentrated in their own cities. A natural gas fired power plant releases 40% less carbon dioxide and fewer pollutants than a coal fired plant and best technology could significantly reduce the particulates, but is expensive.  As the Chinese expand their air pollution, the United States continues to reduce ours. In the U.S. total toxic air releases in 2011 declined 8 % from 2010, mostly because of decreases in hazardous air pollutant emissions, even while total releases of toxic chemicals increased for the second year in a row, according to the EPA. In the mid-Atlantic Region including my home of Virginia, air data shows a decrease of 32.5 million pounds or 13.8 % of chemical releases as compared to 2010.

Last year the Chinese began publishing the small particle, PM2.5 air pollution data for Beijing . Before last year the Chinese had been reporting their air quality based on PM10, which are particles smaller than 10 micrometers but larger than 2.5 micrometers in diameter. According to the US EPA and World Health Organization, the smaller, finer pollutants measured by PM2.5 are especially dangerous for human health. Studies have shown that people increased risk of asthma, lung cancer, cardiovascular problems, birth defects and premature death from particles smaller than 2.5 microns in diameter that lodge deep in the lungs.

The air pollution in Beijing, home to over 20 million people, is easily seen by the smog that wraps the city’s apartment complexes and office buildings many days. The US Embassy in Beijing has their own PM2.5 monitoring station atop their building and has been reporting via an open Embassy Twitter Feedhourly PM2.5 pollution data. The U.S. Embassy reported a series of readings beyond the scale of the air quality index, AQI, (which goes to 500) in fall of 2010 and levels over 700 this past weekend which sparked emergency measures and public response (over the Internet). Current air quality levels from the US Embassy are 175 which is “ unhealthy”but the crisis seem to be over for the moment.  

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