9 days in Grade I*, 2% of days in the year.
129 days in Grade II, 36% of days in the year.
106 days in Grade III, 29% of days in the year.
54 days in Grade IV, 15% of days in the year.
33 days in Grade V, 9% of days in the year.
34 days in Grade VI, 9% of days in the year.
*According to the criteria of the National Environment Air Quality Standard (GB 3095-2012), the air quality is divided into six grades, in which the air pollution index is arranged in ascending order.
Of the 13 rivers running through or around the municipality, 7 have been contaminated more severely while 6 are becoming better. The overall pollution index dropped by 10.0% compared to the previous year.
The environmental noise maintained a stable level in 2013, except a few areas were increasingly affected by construction noise. According to the international criteria, all 5 functioning areas met the daytime noise standard, while 2 passed the night-time noise standard.