Beijing has seen better air quality in August, according to data released by the municipal environmental protection bureau Monday.

The Chinese capital had 28 "blue sky" days this month, three days more than the average level since 2000 and also that in July.

Beijing, however, reported 30 such days in August last year when a massive effort was made to improve the air quality for that month's Olympic Games. Measures implemented at the time, such as keeping half the city's autos off the roads each day, are unrepeatable in the long term.

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. There was 0.106 mg of inhaled particle matter per cubic meter of air in August.

China's air quality index uses different measures to that used by the World Health Organization.

Beijing had 199 "blue sky" days in the year to August, 20 days more than the same period last year. It needs further 61 such days to meet the government target.

In 2008, Beijing had 274 "blue-sky" days, the result of vehicle restrictions for the Olympic Games and a 15-billion-U.S-dollar investment in air quality.