These 17 cities have the worst air quality in the entire country

An oil refinery on Puget Sound, near Seattle.

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An oil refinery on Puget Sound, near Seattle.
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Michael D. Burkhalter / Shutterstock

  • INSIDER analyzed EPA data to find out which cities have had the worst air pollution so far in 2019.
  • The cities with the cleanest air were small and relatively rural, while the places with the dirtiest air were industrial metropolises – but there were some surprises.
  • Air quality has plateaued in the US, but most cities still have clean air by EPA standards.

According to recent reporting from The Associated Press, US air quality is falling after decades of improvement. The reporting, based on Environmental Protection Agency (EPA) data, found that there were 15% more bad air days per city last year than the average from preceding years.

To find out what cities have had the worst air pollution since then, INSIDER looked at EPA data for cities across the United States so far this year. The data, which was last updated in May, shows the Air Quality Index (AQI) – an indicator of overall air quality in relation to health effects – of hundreds of urban centers since January.

The top 5 cities, all of which were small cities such as Enid, Oklahoma, and Malone, New York, all had a median AQI of zero, meaning that on every day that city’s air quality has been measured this year, it was more or less free from pollutants. Bottoming out the list were a combination of metropolises with industrial history and surprisingly small cities close to nature.

Air pollution varies throughout the year thanks to a confluence of factors, from temperature and weather, to traffic and power plant emissions. More smog and ozone are produced in the summer, while inversions occur in the winter, trapping pollutants in valleys. Wildfire season, which typically runs mid-summer through autumn – but has been getting longer and less predictable – can cause AQIs to veer into the “hazardous” range.

Despite plateauing air quality, the majority of US cities have clean air by AQI standards most of the time.


17. The Cincinnati, Ohio area, extending into Indiana and Kentucky, has had more moderate air days than good ones this year. The region’s pollution is <a href=”https://www.cincinnati.com/story/news/2018/04/19/study-cincinnati-one-worst-cities-us-air-pollution/527591002/”>likely</a> due to its coal-fired power plants and diesel emissions.

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EQRoy / Shutterstock

Median Air Quality Index: 51

Number of days measured: 121


16. Oklahoma City has cut ozone levels and <a href=”https://www.lung.org/local-content/_content-items/about-us/media/press-releases/oklahoma-city-air-quality.html”>improved</a> air quality in recent years, but just under half of the days measured so far this year have fallen in the EPA’s “good” range.

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Flickr / Kool Cats Photography over 4 Million Views

Median Air Quality Index: 51

Number of days measured: 91


15. Payson, Arizona is located close to nature and is home to under 16,000 people, but the area has <a href=”http://www.eastvalleytribune.com/local/the_valley/valley-among-nation-s-worst-for-air-pollution-posing-a/article_7bed954e-7e36-11e8-87c7-fbfc1ef96661.html”>often had</a> higher numbers of pollution days than other cities in Arizona.

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Tim Roberts Photography / Shutterstock

Median Air Quality Index: 51

Number of days measured: 90


14. Sault Ste. Marie, Michigan’s AQI has only been reported on one day this year, scoring within the moderate air quality range.

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Dana Foreman / Shutterstock

Median Air Quality Index: 51

Number of days measured: 1


13. Birmingham, Alabama was <a href=”https://www.al.com/news/birmingham/2019/04/birmingham-rated-14th-worst-us-city-for-year-round-particulate-air-pollution.html”>rated</a> among the worst cities in terms of year-round particulate air pollution by the American Lung Association earlier this year.

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Eric in SF/Wikimedia Commons

Median Air Quality Index: 52

Number of days measured: 32


12. The greater Chicago area, including parts of Indiana and Wisconsin, has had good air quality only about 40% of the time. The causes <a href=”https://news.wttw.com/2019/04/24/chicago-among-country-s-most-polluted-cities-study-finds”>might be</a> hotter days and vehicle emissions.

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Kristine Jones / Shutterstock

Median Air Quality Index: 52

Number of days measured: 102


11. Eugene, Oregon has held the title for the <a href=”https://kval.com/news/local/eugene-tops-list-for-worst-air-pollution-in-oregon-in-lung-association-study”>worst</a> air pollution in the state in recent years. Wildfires cause particle spikes in the air, and wintertime inversions trap smoke in the valley.

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Joshua Rainey Photography / Shutterstock

Median Air Quality Index: 52

Number of days measured: 90


10. Denver, Colorado issued a health advisory in March, when its air quality reached its <a href=”https://www.westword.com/news/why-denvers-brown-cloud-is-back-and-why-it-might-get-worse-11263998″>highest level since 1983</a> for that month. The city’s rising population and growing gas and oil industries are the <a href=”https://www.9news.com/article/weather/weather-colorado/what-type-of-air-pollution-does-denver-get/73-6588a6d3-296d-437c-af65-70bd17632a74″>likely</a> culprits.

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Bridget Calip/Shutterstock

Median Air Quality Index: 53

Number of days measured: 104


9. Pittsburgh, Pennsylvania is close to several large coal-fired power plants and coke plants, whose pollutants were trapped by <a href=”https://www.pghcitypaper.com/pittsburgh/whats-behind-those-unhealthy-air-quality-warnings-in-pittsburgh/Content?oid=13474779″>a series of inversions</a> earlier this year.

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REUTERS/David Denoma

Median Air Quality Index: 54

Number of days measured: 91


8. St. Louis, Missouri received an “F” grade for industrial pollution from the American Lung Association, in their 2018 “<a href=”https://www.lung.org/our-initiatives/healthy-air/sota/”>State of the Air</a>” report released this April.

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Joseph Sohm / Shutterstock

Median Air Quality Index: 54

Number of days measured: 91


7. Weirton, West Virginia and Steubenville, Ohio were previously known for their steel production, though an ebb in industry has led to recent <a href=”http://www.theintelligencer.net/news/top-headlines/2019/03/weirton-steubenville-officials-population-loss-tied-to-industry/”>population decline</a>. Most of the days measured this year have fallen in the “moderate” air quality range.

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Sherman Caha / Shutterstock

Median Air Quality Index: 54

Number of days measured: 90


6. Seattle, Washington moved into the top 10 most polluted cities in the ALA’s “State of the Air” report, driven by smoldering wildfires in 2018. Cars and power plants <a href=”https://www.seattlepi.com/seattlenews/article/Seattle-air-quality-bad-low-wildfire-smoke-pollute-13792355.php”>might be</a> to blame for this year’s air quality.

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Oksana Perkins / Shutterstock

Median Air Quality Index: 55

Number of days measured: 32


5. Like the Seattle area, Spokane, Washington’s air was greatly impacted by the 2018 wildfire season. Wildfires have already contributed to unhealthy air quality in the city <a href=”http://www.spokesman.com/stories/2018/aug/21/spokanes-air-quality-youve-got-questions-weve-got-/”>this year</a>.

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Nagel Photography / Shutterstock

Median Air Quality Index: 55

Number of days measured: 31


4. Stockton, California is part of a region flush with air pollution, <a href=”https://www.motherjones.com/environment/2018/12/californias-fertile-valley-is-awash-in-air-pollution/”>thanks to a combination</a> of cattle farming, dusty crops, oil fields, and traffic. Stagnant weather and wildfires have <a href=”https://www.kcra.com/article/stockton-air-quality-early-spring-devils-mix-for-breathing/16770824″>exacerbated</a> the situation.

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Terrance Emerson / Shutterstock

Median Air Quality Index: 57

Number of days measured: 37


3. Yakima, Washington, in the center of the state, has recently been plagued with the <a href=”https://fox41yakima.com/yakimas-air-quality-recorded-as-the-worst-ever/”>worst air</a> the city has ever recorded. Its location in a valley makes it harder for polluted air to escape.

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Michael S. Shannon / Wikimedia Commons / CC 2.0 Attribution

Median Air Quality Index: 57

Number of days measured: 31


2. Missoula, Montana, in the northern Rockies, has <a href=”https://missoulian.com/news/local/report-climate-change-worsening-air-pollution-in-missoula-other-mt/article_45c05050-f7c7-551e-b972-b964b6d46ad0.html”>ranked</a> among the healthiest in the country in terms of ozone, but wildfires are increasingly threatening its air quality. This spring, wildfire smoke from Canada drifted into the city and <a href=”https://kpax.com/news/missoula-county/2019/05/31/air-quality-unhealthy-for-sensitive-groups-in-missoula/”>created unhealthy conditions</a> for sensitive groups.

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Keegan Connell / Shutterstock

Median Air Quality Index: 63

Number of days measured: 31


1. Seneca Falls, home of the 1848 women’s rights convention, is located in the picturesque Finger Lakes region of upstate New York. The area’s air is <a href=”https://www.lung.org/local-content/_content-items/about-us/media/press-releases/new-york-sota.html”>typically clean</a>, but so far in 2019, the city’s air quality has been unhealthy for sensitive groups on 11 of the 16 days reported.

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Debra Millet / Shutterstock

Median Air Quality Index: 114

Number of days measured: 16