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Study shows Beijing traffic controls during November summit cut pollution by 40 percent

Study shows Beijing traffic controls during November summit cut pollution by 40 percent

Strict traffic controls that Beijing imposed during a summit with African leaders last year produced a significant drop in pollution, a positive sign for the city's Olympic planning, according to a recently released study.
The researchers from Harvard University and the Royal Netherlands Meteorological Institute studied satellite data and found that levels of NOx, a class of nitrogen oxides thought to contribute to global warming, fell 40 percent from normal during the November summit.
The drop was larger and more rapid than expected, the researchers wrote in their findings, published in the April 28 issue of Geophysical Research Letters, a journal of the American Geophysical Union.
Beijing's normally gridlocked streets and smog-choked skies are among the leading concerns as the city prepares to host the 2008 Olympics. The summit, in which Beijing hosted dignitaries from 48 African countries, was seen as a test of the types of contingency measures the Chinese capital could employ for the games.
City authorities used a combination of fiat and persuasion to get an estimated 800,000 of the city's 2.8 million vehicles off the road. The result was nearly a week of smooth traffic and low pollution.
"We expected a drop in nitrogen emissions, but not to this extent, and after only a short period of time," Harvard's Yuxuan Wang said in the research findings, which analyzed ozone emissions data collected by NASA's Aura satellite.
Previous research has shown a "weekend effect" in which lighter traffic has led to reduced nitrogen emissions over industrial areas in the United States, Europe and Japan, the researchers said.
Wang's team had expected that Beijing would need to cut traffic by 50 percent to see a 40 percent reduction but instead the city achieved that by taking an estimated 30 percent of the vehicles off the roadways.
The researchers called for further study on gasoline sales and other related issues to determine why the drop-off was more pronounced.


Updated : 2021-06-22 13:09 GMT+08:00