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Nearly one in four Americans lives in a county with poor air quality. That figure comes from the EPA — and while conditions have gradually improved since the Clean Air Act passed in 1970, millions of people are still regularly breathing air that doesn't meet national health standards.
The causes vary by region. In the West, ozone and wildfire smoke are the dominant problems. In the industrial Midwest and mid-Atlantic, particle pollution and sulfur dioxide play a larger role. Economically disadvantaged communities tend to bear a disproportionate share of the burden — research consistently shows that higher pollution levels cluster in lower-income areas.
The good news is that outdoor air quality, while imperfect, has improved measurably over the past five decades — even as the U.S. economy, population, and energy use have all grown. The harder reality is that the most polluted metros in 1980 are still, for the most part, the most polluted today.
To identify which metropolitan areas have the worst and best air quality, researchers at Filterbuy analyzed median Air Quality Index (AQI) values published annually by the EPA. Higher AQI values indicate higher pollution and lower air quality. Only metros with at least 500,000 residents were included.
While many Americans are still living in places with unhealthy levels of air pollution, conditions have been improving in recent decades. Through EPA efforts and the passage of the Clean Air Act, the U.S. has seen gradual improvement in air quality and a decline in the emissions of common pollutants since 1970. CO2 emissions have also shown small declines since 2010. Such improvements have occurred even with steady increases in the gross domestic product, travel, total population, and energy consumption.
Still, air quality in many areas, especially in the Western U.S., does not meet national standards. In addition to causing environmental issues, poor air quality can have negative consequences for individual health, which can be particularly detrimental to those already suffering from certain health problems such as asthma and cardiovascular disease. Additionally, new research indicates that economically disadvantaged communities are more likely to face higher levels of pollution. Furthermore, while the US has improved as a whole, the most polluted areas from 1980 are still among the most polluted today.
To identify metropolitan areas with the worst (and best) air quality, researchers from Filterbuy analyzed median Air Quality Index (AQI) values for 2019. These values, published annually by the EPA, are a measure of an area’s air pollution. Higher AQI values indicate that an area experiences higher pollution levels and lower air quality.
For the purpose of this report, only metropolitan areas with at least 500,000 residents were included. Here are the metropolitan areas with the worst (and best) air quality in the nation.
TRENDING Replacing home air filters regularly can dramatically improve the air quality in your home. If you are dealing with particularly problematic conditions, consider using MERV 13 air filters.
Photo Credit: Alamy Stock Photo
Photo Credit: Alamy Stock Photo
Photo Credit: Alamy Stock Photo
Photo Credit: Alamy Stock Photo
Median Air Quality Index for 2019: 67
Good days: 119
Moderate days: 151
Unhealthy or hazardous days: 95
Maximum Air Quality Index observed in 2019: 548
Population: 896,764
Photo Credit: Alamy Stock Photo
Median Air Quality Index for 2019: 64
Good days: 87
Moderate days: 253
Unhealthy or hazardous days: 25
Maximum Air Quality Index observed in 2019: 169
Population: 3,343,364
Photo Credit: Alamy Stock Photo
Median Air Quality Index for 2019: 60
Good days: 139
Moderate days: 160
Unhealthy or hazardous days: 66
Maximum Air Quality Index observed in 2019: 187
Population: 994,400
Photo Credit: Alamy Stock Photo
Median Air Quality Index for 2019: 58
Good days: 91
Moderate days: 252
Unhealthy or hazardous days: 22
Maximum Air Quality Index observed in 2019: 154
Population: 2,932,415
Photo Credit: Alamy Stock Photo
Median Air Quality Index for 2019: 56
Good days: 129
Moderate days: 220
Unhealthy or hazardous days: 16
Maximum Air Quality Index observed in 2019: 161
Population: 2,324,743
Photo Credit: Alamy Stock Photo
Median Air Quality Index for 2019: 56
Good days: 135
Moderate days: 217
Unhealthy or hazardous days: 13
Maximum Air Quality Index observed in 2019: 142
Population: 4,326,442
Photo Credit: Alamy Stock Photo
Median Air Quality Index for 2019: 55
Good days: 121
Moderate days: 227
Unhealthy or hazardous days: 17
Maximum Air Quality Index observed in 2019: 174
Population: 9,498,716
The data used in this analysis is from the EPA’s 2019 Air Quality Index Report. The Air Quality Index (AQI) is EPA’s method for reporting daily air quality by location based on National Ambient Air Quality Standards. Higher AQI values correspond to higher levels of pollution and worse air quality. AQI values below 50 are considered good; AQI values between 51 and 100 are considered moderate; and AQI values that exceed 100 are considered unhealthy (at first for sensitive groups and then for everyone as values increase).
To determine the locations with the worst air quality, metropolitan areas were ranked by their respective median AQI values, with high AQI values corresponding to worse air quality. In the event of a tie, the location with the higher maximum AQI value was considered to have worse air quality.
Population data is from the U.S. Census Bureau’s 2018 American Community Survey 1-Year Estimates. Only metropolitan areas with at least 500,000 residents were included in the report.
