In China, eight of the top 10 cities are within 250 miles of Beijing. In the U.S., eight of the top 10 are in California.



China Air Daily

Measured in PM2.5 concentration levels in micrograms per cubic meter

Source: Chinese Ministry of Environmental Protection, American Lung Association

Caption information

Measured in PM2.5 concentration levels in micrograms per cubic meter

Source: Chinese Ministry of Environmental Protection, American Lung Association