Seven cities in Beijing's neighboring Hebei Province were among the 10 most polluted in September, according to a ranking released by the Ministry of Environmental Protection (MEP) on Thursday.
The cities in Hebei are Hengshui, Xingtai, Tangshan, Handan, Baoding, Langfang and Shijiazhuang, according to the monthly report, which reviews air quality in 74 Chinese cities.
Jinan, capital city of eastern China's Shandong Province, had the worst air quality last month, with more than half of the days in September polluted.
The ministry said ozone overtook PM2.5 to become the main air pollutant in 74 Chinese cities in September.
In Beijing, nearly 27 percent of September days were polluted, with no days of heavy pollution, and the main pollutants were PM2.5 and ozone, said the report.
The Beijing-Tianjin-Hebei region witnessed improved air quality in September while air quality in the Pearl River Delta region last month was worse than August.
The Yangtze River Delta region did not see much change in air quality last month.
The MEP also named the 10 cities with the best air quality in September, which were Haikou, Lhasa, Zhoushan, Fuzhou, Kunming, Xiamen, Guiyang, Harbin, Zhuhai and Yancheng.
