Improved air quality during Beijing Olympics could inform pollution-curbin...( The air in Beijing during the 2008 O...)

The air in Beijing during the 2008 Olympics was cleaner than the previous year's, due to aggressive efforts by the Chinese government to curtail traffic, increase emissions standards and halt construction in preparation for the games, according to a Cornell study.

Led by Max Zhang, assistant professor of mechanical and aerospace engineering, the study indicates that such measures as regulating traffic density and encouraging public transportation can have a significant impact on local air quality.

"We hope our study can help or advise local regulators and policymakers to adopt long-term sustainable emission controls to improve air quality," Zhang said. "That's our mission."

Published online July 11 in the journal Atmospheric Environment, the study was based on air quality readings before, during and after the Olympics. Leading up to the Olympics, the Chinese government barred more than 300,000 heavy-emission vehicles mostly trucks from the roads. The city also implemented rules in which only some people were allowed to drive on certain days based on their license plate numbers. As a result, close to 2 million vehicles were pulled from the roads. Other mandates involved halting construction and decreasing the use of coal in favor of natural gas for electricity.

In 2007 and 2008, the researchers collected air quality data from equipment installed at two elevations on a building in the heart of Beijing. They also tracked emissions from vehicles in different areas of the city by following randomly selected cars and trucks in a minivan equipped with sensitive instruments for detecting carbon particles, including carbon monoxide, carbon dioxide and black carbon, or soot.

Among the researchers' conclusions: Black carbon pollution is significantly greater at ground level than at higher elevations, and diesel trucks are a major source of black carbon emission during the summer in Beijing. These particles are not onl
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