A Year in Air Quality, 2015

The number of days in which the average air quality level reached certain health thresholds defined in the Environmental Protection Agency’s Air Quality Index. The readings reflect concentrations of the pollutant PM2.5 that have been scaled to health categories in the index, or AQI.

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Notes

The data reflect average daily PM2.5 levels, scaled to the EPA Air Quality Index, as captured by sensors at single locations in each city: Beijing (U.S. Embassy), Shanghai (U.S. Embassy), Seoul (Yongsan District), Los Angeles (Chinatown), New York (Lower Manhattan)

Source: U.S. State Department (Beijing & Shanghai); City of Seoul Research Institute of Public Health and Environment (Seoul); U.S. Environmental Protection Agency (Los Angeles & New York)

Credit: Matt Stiles for NPR