Most Polluted Cities 1
Most Polluted Cities 1

While air pollution in the U.S. has improved remarkably since the passage of the Clean Air Act, the Environmental Protection Agency (EPA) estimates that 137 million people nationwide still live in counties where air pollution levels exceeded air quality standards. In 2018, the U.S. emitted 76 million tons of pollution into the atmosphere, which according to the American Lung Association, contributes to increased rates of lung cancer and reduced lifespans among American families.

Air quality standards for common pollutants that pose a threat to public health are managed by the EPA. These pollutants include ozone, fine and coarse particulate matter (PM2.5 and PM10), sulfur dioxide, lead, carbon monoxide, and nitrogen dioxide. From 1980 to 2018, the greatest air quality improvements occurred in lead, sulfur dioxide, and carbon monoxide levels.

According to the EPA, efforts to remove lead from automobile gasoline alone helped reduce levels of lead in the air by 89 percent over three decades. Similarly, a 1990 update to the Clean Air Act known as the Acid Rain Program set a permanent cap on emissions of sulfur dioxide and nitrogen oxides from power plants. The cap helped reduce sulfur dioxide to 9.0 percent of the 1980 value and the level of nitrogen dioxide to 39 percent over the same time period.

Most Polluted Cities Cities 3
Most Polluted Cities Cities 3

While levels of nitrogen dioxide, carbon monoxide, sulfur dioxide, and lead are all below 40 percent of their respective 1980 values, ozone and particle pollution continue to present a major public health risk. With these trends in mind, researchers at 360 Quote analyzed data from the EPA to find the U.S. metropolitan areas with the highest levels of air pollution.

The EPA uses a measure known as the Air Quality Index (AQI) to report daily air quality, with higher values corresponding to greater levels of air pollution. Values between 0-50 are considered good; values between 51-100 are moderate; values between 101-150 are unhealthy for sensitive groups; and values above 151 are unhealthy for the general public. Researchers used AQI data to determine air quality rankings for small, midsize, and large metropolitan areas.

The findings among the small and midsize metros are in line with the findings among the large metros. Specifically, locations in California make repeated appearances on these lists. When comparing air pollution levels of large metropolitan areas, five of the top 15 metros were found to exist in the coastal state. The prevalence of California locales is even higher among the top 15 small and midsize metros.

Here are the large metropolitan areas with the worst air quality:

MetroRankMedian AQIMax AQIGood daysModerate or unhealthy for sensitive groups daysUnhealthy, very unhealthy, or hazardous daysMost common pollutant
Riverside-San Bernardino-Ontario, CA1972962527565Ozone
Phoenix-Mesa-Scottsdale, AZ2779964230419Coarse particulate matter (PM10)
Los Angeles-Long Beach-Anaheim, CA3772013531020Ozone
Denver-Aurora-Lakewood, CO464174832748Ozone
San Diego-Carlsbad, CA564143732920Ozone
Sacramento–Roseville–Arden-Arcade, CA66131412421724Ozone
Salt Lake City, UT7611691382252Ozone
Las Vegas-Henderson-Paradise, NV8611541222421Ozone
Chicago-Naperville-Elgin, IL-IN-WI9571771172426Fine particulate matter (PM2.5)
Philadelphia-Camden-Wilmington, PA-NJ-DE-MD10551641322303Fine particulate matter (PM2.5)
Pittsburgh, PA11551541362281Fine particulate matter (PM2.5)
St. Louis, MO-IL12541821572062Fine particulate matter (PM2.5)
Detroit-Warren-Dearborn, MI13541511372262Fine particulate matter (PM2.5)
San Francisco-Oakland-Hayward, CA145324514720612Fine particulate matter (PM2.5)
New York-Newark-Jersey City, NY-NJ-PA15532101562063Fine particulate matter (PM2.5)

For more information, a detailed methodology, and complete results, you can find the original report on 360 Quote’s website: https://www.buyautoinsurance.com/air-pollution-worst-cities/

Stuart
Stuart is the founder, writer and wrangler at several sites including Gastronomic SLC, Utah Now and, The Utah Review; Stuart is a former restaurant critic of more than five years, working for the Salt Lake Tribune and has worked extensively with other local publications from Utah Stories through to Salt Lake Magazine and Visit Salt Lake.