In September, the average PM2.5 concentration across 339 prefecture-level and above cities nationwide was 16.0 micrograms per cubic meter, a 14.4% decrease year-on-year. The average PM10 concentration was 31 micrograms per cubic meter, down 11.4% year-on-year. The average O3 concentration was 119 micrograms per cubic meter, a 11.2% decrease year-on-year. The average SO₂ concentration was 7 μg/m³, unchanged year-on-year; the average NO₂ concentration was 14 μg/m³, down 6.7% year-on-year; and the average CO concentration was 0.7 mg/m³, unchanged year-on-year.

In September, the average proportion of days with good or excellent air quality across 339 prefecture-level and above cities nationwide reached 96.2%, an increase of 3.4 percentage points year-on-year. The average proportion of days with severe or worse pollution was 0.6%, up 0.5 percentage points year-on-year. The average proportion of days with exceedances caused by sandstorms was 1.4%, with severe or worse pollution accounting for 0.6% of these days.

From January to September, the average PM2.5 concentration across 339 prefecture-level and above cities was 26.0 micrograms per cubic meter, down 5.1% year-on-year; the average PM10 concentration was 45 micrograms per cubic meter, down 4.3% year-on-year; the average O3 concentration was 143 micrograms per cubic meter, down 2.7% year-on-year; The average SO₂ concentration was 7 μg/m³, down 12.5% year-on-year; the average NO₂ concentration was 17 μg/m³, down 5.6% year-on-year; and the average CO concentration was 0.9 mg/m³, down 10.0% year-on-year.

From January to September, the average proportion of days with good or excellent air quality across 339 prefecture-level and above cities nationwide was 87.6%, an increase of 1.8 percentage points year-on-year; the average proportion of days with severe or worse pollution was 1.1%, unchanged year-on-year. The average proportion of days with exceedances caused by sandstorms was 3.1%, of which the proportion of days with severe or worse pollution was 0.7%.

Proportion of Days by Pollution Level in 339 Prefecture-Level and Above Cities, January-September 2025

List of Top 20 and Bottom 20 Cities by Air Quality in 168 Key Cities, January-September 2025

From January to September, the top 20 cities with the best air quality among 168 key cities were Haikou, Lhasa, Huangshan, Zhangjiakou, Guiyang, Fuzhou, Zhuhai, Huizhou, Zhoushan, Lishui, Xiamen, Shenzhen, Zhongshan, Kunming, Taizhou, Ya'an, Yichun, Chengde, Nanning, and Jiangmen. The bottom 20 cities with poorer air quality were Xianyang, Lanzhou, Tianjin, Taiyuan, Jiaozuo, Kaifeng, Xinxiang, Xi'an, Xuzhou, Linyi, Hebi, Tangshan, Anyang, Xingtai, Liaocheng, Dezhou, Heze, Yangquan, Linfen, and Zibo.

From January to September, among 168 key cities, the top 20 cities with the lowest PM2.5 concentrations were Lhasa, Haikou, Shenzhen, Zhoushan, Zhuhai, Huizhou, Zhongshan, Zhangjiakou, Xiamen, Fuzhou, Lishui, Dongguan, Guiyang, Huangshan, Guangzhou, Chengde, Jiangmen, Foshan, Kunming, and Zhaoqing; The bottom 20 cities with the highest PM2.5 concentrations were Jingzhou, Shangqiu, Luohe, Jingmen, Xianyang, Xiangyang, Anyang, Zhoukou, Kaifeng, Hebi, Xuzhou, Xuchang, Suizhou, Suqian, Xi'an, Huaibei, Heze, Fuyang, Zaozhuang, and Changde.

Source: Ministry of Ecology and Environment