Beijing has recorded six fewer days of so called "blue sky" days, or grade I and grade II air quality, in the first half of the year.

The decrease from the same period last year came as the Chinese capital was hit by more sandy-dusty weather in the spring, the city's environment protection agency stated in a monthly press release issued Wednesday.

The city reported 140 days with grade I and grade II air quality in the first six months, 126 days short of the 2010 target, it said.

Beijing uses a five-grade classification of air quality on the basis of pollution indices, with grade I being the best and grade V the worst. Days with grade I and II air quality are regarded as "blue sky" days.

Beijing reported the best air quality in nine years in the first half of last year. It recorded 146 blue sky days, 23 more days than the same period in 2008.

The city was hit by dust and sand 19 times from March to May this year, up from six a year earlier, which affecting the air quality of 21 days, it said.