Beijing will replace or remove some 300,000 heavily polluting vehicles within one year in an attempt to further improve its air quality. All heavily polluting vehicles will be banned within the sixth ring road by 1 October 2009.

Beijing has multiple ring roads (beltways)—the sixth ring road (physically the fifth), is currently the outermost at some 15-20 km from the center of Beijing. This toll expressway ring road links Beijing with Shunyi District, Tongzhou District, Changping District and Daxing District.

Currently, the number of heavily polluting vehicles accounts for about 10 percent of the total in the capital, but the pollutants they emit cover about half of the total from vehicles. The air quality at night often showed a pollution peak, which was mainly due to the large number of such vehicles running into the downtown, according to Feng Yuqiao, a Beijing Environmental Protection Bureau official.