Beijingers breathed in the least amount of pollutant in nine years in April, with a record 23 "blue sky days" and zero "hazardous day", the environment watchdog said Friday.

Photo taken on Dec. 31, 2008 shows a view of a street under the blue sky in Beijing, capital of China. Beijing had 274 blue-sky days this year, 28 more than last year, meaning that air quality in the capital improved for 10 consecutive years, according to Beijing Environmental Protection Bureau. [file photo]

For the first time since 2000, not a single day in April was rated "poor" or "hazardous", said Du Shaozhong, deputy chief of Beijing municipal environmental protection bureau.

Beijing has a five-grade classification of air quality: a reading below 50 is "excellent;" from 51 to 100 "fairly good;" 101 to 200 "slightly polluted;" 201 to 300 "poor;" and more than 301 "hazardous." Days with excellent or fairly good air quality are counted as blue sky days.

"Twenty-three out of the 30 days in April were rated 'blue sky days', four days more than the same period of last year and 10 days more than year 2000," said Du.

Seven days were "slightly polluted", including the six days from April 8 to 13, and April 18, he said. "The rapid rise of temperature and absence of wind on those days caused pollutants to stay."

The monthly average density of particulate matter, the top pollutant in Beijing, measured 0.12 mg in April, down 25 percent year-on-year and 40 percent compared with the same period of 2000, he said.

Beijing has experienced 96 "blue sky days" in the first four months, about 80 percent of the total but still 164 days away from the projected minimum of 260 blue sky days for this year.

The projection, however, was rather conservative as the number of blue sky days had risen to 274 last year from 100 in 1998, when the capital launched the blue sky drive.

(Xinhua News Agency May 1, 2009)