23. Xingtai, North China
> Population: 742,000
> Average annual PM2.5 pollution per cubic meter: 87.0 micrograms
> Average annual PM10 pollution per cubic meter: 185.9 micrograms
22. Shijiazhuang, North China
> Population: 3.3 million
> Average annual PM2.5 pollution per cubic meter: 89.0 micrograms
> Average annual PM10 pollution per cubic meter: 147.0 micrograms
21. Ji’nan, East China
> Population: 4.0 million
> Average annual PM2.5 pollution per cubic meter: 90.0 micrograms
> Average annual PM10 pollution per cubic meter: 192.3 micrograms
20. Ulaanbaatar, Mongolia
> Population: 1.4 million
> Average annual PM2.5 pollution per cubic meter: 92.2 micrograms
> Average annual PM10 pollution per cubic meter: 196.9 micrograms
19. Baoding, North China
> Population: 1.1 million
> Average annual PM2.5 pollution per cubic meter: 93.0 micrograms
> Average annual PM10 pollution per cubic meter: 147.0 micrograms