City Rankings

The American Lung Association "State of the Air 2020" report ranks the metropolitan areas based on ozone and particle pollution during 2016, 2017 and 2018. For particle pollution, we rank separately the areas with high year-round (annual average) levels and high short-term levels (24-hour) found in monitoring sites across the United States. We take official data from the U.S. Environmental Protection Agency (EPA) to compile the rankings. For more information about how we grade and rank cities, go to Methodology.