According to list of air quality improvement in 168 cities from January to June released by the Ministry of Ecology and Environment, Changchun ranks the sixth. The comprehensive index of ambient air and the number of days with first-class air quality remained the best compared with that of previous years. 

With a total of 118 days by June 30 this year, the number of days with good air quality amounted to 149, a year-on-year increase of 21 days, accounting for 82.3%, or a surge of 12 percentage points, including 62 first-class days, a year-on-year increase of 7 days; The comprehensive ambient air index was 4.12, a year-on-year decrease of 0.82 at a ratio of 16.6%.