Beijing, May 1 (Inditop) Residents here breathed in the least amount of pollutants in nine years in April, with a record 23 “blue sky days” and zero “hazardous days”, an official said Friday.

Days with excellent or fairly good air quality are counted as blue sky days.

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”.

“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.”

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.