Beijing has met its 2008 target of 256 blue sky days as Sunday marked another day of good air quality.

As of Sunday, the number of the city's blue sky days was 25 more than that of the same period last year, according to the Beijing Environmental Protection Monitoring Center.

Beijing has met its 2008 target of 256 blue sky days as Sunday marked another day of good air quality. As of Sunday, the number of the city's blue sky days was 25 more than that of the same period last year, according to the Beijing Environmental Protection Monitoring Center.

From January to November, major pollution indices like concentrations of sulfur dioxide and carbon monoxide, fell by up to 27.8 percent, the center's statistics showed.

Beijing adopts a five-grade classification of air quality on the basis of pollution indices. Grade I is the best and Grade V the worst. Days with Grade I and II air quality are regarded as blue sky ones.

"The remarkable air quality improvement this year should be mainly attributed to the long-term effects of the city's consistent pollution control measures since 1998," said Du Shaozhong, deputy director of Beijing Environmental Protection Bureau.

He added that another important factor was the temporary emission cut measures during the Olympics. Beijing allowed odd and even-numbered vehicles on roads on alternate days and ordered heavily polluting industries to reduce pollution during the Games.

Beijing had 246 blue sky days in 2007. Since 1998, the capital has invested more than US$15 billion to improve its air quality.