In May, the average PM2.5 concentration in 339 prefecture-level and above cities nationwide was 24.5 micrograms per cubic meter, up 8.9% year-on-year; the average PM10 concentration was 46 micrograms per cubic meter, up 4.5% year-on-year; the average O3 concentration was 156 micrograms per cubic meter, down 3.1% year-on-year; the average SO2 concentration was 7 micrograms per cubic meter, down 12.5% year-on-year; the average NO2 concentration was 15 micrograms per cubic meter, a year-on-year decline of 6.2%; and the average concentration of CO was 0.7 mg/m3, flat year-on-year.

In May, the average proportion of good air quality days in 339 prefectural-level and above cities nationwide was 81.9%, up 3.7 percentage points year-on-year, while the average proportion of days with heavy or above pollution was 0.9%, up 0.4 percentage points year-on-year. The average proportion of days exceeding the standard caused by dusty weather was 4.2%, of which the proportion of days with heavy and above pollution was 0.9%.

Proportion of days at all levels in 339 cities at prefecture level and above nationwide in May 2025

List of Top 20 and Bottom 20 Cities in Air Quality Ranking of 168 Key Cities in May 2025

In May, among the 168 key cities: the top 20 cities with better air quality were, in order, Haikou, Lhasa, Kunming, Guiyang, Nanning, Zhongshan, Zhuhai, Huangshan, Shenzhen, Huizhou, Lishui, Urumqi, Zhoushan, Fuzhou, Xiamen, Taizhou, Ya'an, Yichun, Jiangmen, and Zhangjiakou; and the bottom 20 cities with worse air quality were, in order, Tangshan, Kaifeng, Tianjin, Langfang, Zhengzhou, Deyang, and Xuchang, Jiaozuo, Xiangyang, Xinxiang, Hebi, Mianyang, Luoyang, Pingdingshan, Luohe, Baoding, Taiyuan, Zhoukou, Yangquan and Bengbu.

In May, among the 168 key cities: the top 20 cities with lower PM2.5 concentrations were, in order, Lhasa, Haikou, Zhongshan, Zhuhai, Shenzhen, Kunming, Zhoushan, Urumqi, Huizhou, Nanning, Ningbo, Lishui, Xiamen, Guiyang, Dongguan, Guangzhou, Foshan, Jiangmen, Zhangjiakou, and Zhaoqing; the bottom 20 cities with higher PM2.5 concentrations were, in order, Xiangyang, Neijiang, Mianyang, Kaifeng, Huainan, Jingmen, Suizhou, Deyang, Xuchang, Luohe, Nanchong, Hebi, Fuyang, Zigong, Zhoukou, Shangqiu, Tangshan, Langfang, Ziyang and Zhengzhou.

Source: Ministry of Ecology and Environment