Reducing Cars Lowers Pollution

As China looks to clean Beijing’s notoriously polluted air for the 2008 Summer Olympics, a soon-to-be-released study by Harvard researchers has determined that restricting vehicles in China’s capital is a surprisingly effective and fast-acting way to reduce air pollution.

The study, conducted by a professor and two post-doctoral fellows at Harvard’s School of Engineering and Applied Sciences, used satellite data to examine the effects of a three-day limit on vehicle traffic in Beijing during the November 2006 Summit of the Forum on China-Africa Cooperation.

By removing about 800,000 of Beijing’s nearly three million vehicles from the road during the conference—and pushing people to make greater use of busses and subways—officials cut the city’s concentration of a certain type of harmful nitrogen oxide by 40 percent.

Yuxuan Wang, one of the post-doctoral fellows who worked on the study, said that the results were promising.

“We do see large reduction in emissions, so that demonstrates traffic restrictions were very effective,” she said. The November 2006 program “is the first of a series of experiments [leading to the] Olympic Games in 2008. I’m sure they’ll do similar things or even larger [restrictions] in August 2008.”

Chris Nielsen, the executive director of the China Project at Harvard, said that Chinese officials consider the Beijing Olympics to be a “showcase” of the country’s rapid development, and that Chinese officials do not want air pollution to detract from the event.

The researchers of the study—which is being published in the journal Geophysical Research Letters—are affiliated with the China Project, which is part of the Harvard University Center for the Environment.

K. Folkert Boersma, another post-doctoral fellow who worked on the report, stressed the importance of new satellite technologies in collecting data on Beijing’s environment over the three-day period of vehicle restrictions.

Because of their precision, the newest satellites could eventually be used to track global pollution, Boersma said.

“There’s nothing to hide,” he said. “The whole [global] community is really after the most accurate satellite technology to track down where most pollution comes from, to see if countries are in compliance with international treaties.”

The Dutch-Finnish Ozone Monitoring Instrument (OMI), used for this research, is unique for its daily global coverage.

“Previously satellites...looked at [regions] every three days or every week, but OMI has the advantage of seeing the same place every day,” Wang added.