Beijing car ban shows dramatic pollution cuts are possible

The analysis of restrictions on the city’s motorists during a conference last November shows that while traffic was down just 30%, some pollutants fell by as much as 40%.

The study was conducted by a team of researchers from the USA’s Harvard University, led by professor Micheal McElroy.

China’s restrictions on Beijing drivers coincided with the Summit of the Forum on China-Africa Cooperation, during which an estimated 800,000 of Beijing’s 2.82 million vehicles were taken off the road.

Using satellite observation, the Harvard team found that levels of NOx, a group of gases which contribute to the formation of ozone-based smog and global warming as well as causing more immediate health problems, fell by 40% during this period.

“I don’t think a proper analysis has ever been made before of such a remarkable shift of environmental policy in such a short period of time,” said professor McElroy.

“Traffic restrictions implemented during the Sino-African Summit were remarkably successful in reducing emissions of NOx,” said researcher Yuxuan Wang.

“We expected a drop in nitrogen emissions, but not to this extent, and after only a short period of time.”

Recent estimates say that during warmer months when heating systems are generally off, nearly 70% of all NOx emissions in the Beijing area are from vehicular emissions.

Last November’s driving restrictions ranged from regulating access to specific roads to restricting use of both private and government vehicles. China is expected to duplicate these traffic restrictions during the 2008 Summer Olympic Games.

“I think the real value here is that these kinds of restrictions can really bring about significant change,” said McElroy.

While he and his team are hesitant to leap to conclusions, they maintain that similar events in the future, such as the 2008 Olympic Games themselves and traffic reductions expected to be implemented this summer as a rehearsal for the Olympics, will offer valuable opportunities for further study of the processes determining the quality of air over Beijing.

“Coordinated observations on such occasions can provide precious opportunities to test and refine our understanding of atmospheric chemistry not only for Beijing but also for the large region of East Asia,” he said.

Sam Bond