Cyclists cross Chang'an Avenue amid strong winds in central Beijing Dec 2, 2010. [Photo/Agencies]

BEIJING - The sky appears blue, but the air remains polluted, Beijing's environmental watchdog ruled Thursday as strong winds blew away the murky haze that shrouded China's capital for days.

Beijing Environmental Monitoring Center's daily report shows that Beijing's average air quality from mid-day Wednesday to Thursday was "slightly polluted" (pollution reading 101 to 200).

Test results from 14 out of the 27 monitoring sub-stations in the city even show the day's air was "poor" (201 to 300) or "hazardous" (over 301).

The municipal government has vowed to achieve 266 "blue sky days" this year. It seems the target is reachable as as of Thursday Beijing is short of only two "blue sky days," environmental watchdog data show.

Beijing's notoriously air pollution, characterized by the usual thick smog in the sky, hit media headlines anew on November 19 when the U.S. Embassy, which has been using an independent hourly air quality monitoring system, described pollution levels in the capital as "crazy bad".

The phrase was later deleted as embassy officials said they would find more proper language to describe when air quality index goes beyond its highest point.

The U.S. Embassy uses PM 2.5 to track pollutants, a finer measurement than PM 10 being used by the Chinese government. Health experts say PM 10 monitor relatively coarse particulars but overlook those dust-like but deadly pollutants.

Officials with Beijing environmental bureau said the results issued by the U.S. Embassy's monitoring system can not represent the overall air quality in Beijing. But they said they are working to refine the government's monitoring systems to track smaller pollutants.