Du Shaozhong: Fewer vehicles, cleaner beijing air

For four days, from August 17-20, Beijing restricted the number of motor vehicles on roads, based on license plate numbers.

Speaking at Tuesday's press conference, Du attributed the accurate measurement to two factors: 1. The weather was ideal, in that it was not conducive to air pollution dispersion, and allowed for an accurate measurement of the pollution; 2. City residents cooperated and kept more than one million motor vehicles off of roads.

Furthermore, said Du, the test results clearly indicate that limiting the number of motor vehicles on roads had a positive effect on improving Beijing's air quality, reducing air pollutants by 15-20%, and thereby achieving level 2 air quality (air pollution index between 50-100) for all four days.

Du pointed out that on Tuesday, when road traffic returned to normal, the sky was clear and blue, but the air quality was only at level 3, with the air pollution index at 116. He pointed out that a blue sky does not necessarily equal good air quality. A true "blue skies" day should be supported with numbers.

Various research organizations including the Beijing Environmental Monitoring Center, the Chinese Academy of Sciences, Peking University, Tsinghua University, etc. were involved in administering the numerous tests, employing various scientific methods in order to ensure accurate measurements.