The Most Polluted Cities In The US

The Most Polluted Cities In The US

For most people, pollution isn’t something you notice until you can see it. For instance on a hot summer day when the smog becomes visible, or when you see those photos of trash that hikers have left on Mount Everest. But if you live in a city, the pollution you’re dealing with is insidious. Invisible chemicals in the water or tiny particles in the air can have a cumulative impact on a person’s health. People who live in an area with high levels of air pollution are at just as much risk of lung damage as that caused by smoking. We took a look at a variety of sources to compile a list of the most polluted cities in the US.

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40. Cincinnati, Ohio

Cincinnati has a reputation for getting things done when it comes to business, and that industriousness is partly to blame for its low air quality. Though it’s pollution is moderate and poses no immediate threat to human health—apparently—it still has issues with particle pollution, and this is from construction sites, unpaved roads, automobiles, and power plants.

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39. Knoxville, Tennessee

Knoxville is one of the few cities on this list that has actually been making progress in the right direction—as in, it’s air quality is getting better. However, keeping the city free of pollution is a monumental task. Knoxville is in a valley, surrounded by mountains that keep the smog and soot from industrial factories in, a problem it has in common with a lot of other polluted US cities.

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38. Shreveport, Louisiana

Chronic respiratory disease is the fourth-leading cause of death in Louisiana, and air pollution is partly to blame. Shreveport scores low on the air quality index due to its high levels of ozone—otherwise known as smog. Also, Louisiana residents have been indicted as the worst litterbugs in the US, the state parks director  called it “the trashiest state in the US.” (source) Ouch. 

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37. Sheboygan, Wisconsin

When Sheboygan was designated as having a low quality air rating, its leaders were outraged. According to them, Sheboygan is a victim of dirtier cities upwind, like Chicago, blowing their smog into the city limits. Sure that probably doesn’t help, but Milwaukee has one of the biggest manufacturing sectors in the US, which means lots of factories churning pollution into the air. And you can’t blame everything on Chicago.

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36. Hartford, Connecticut

A few years ago a study determined that air pollution was the cause of death or hospitalization for over 600 people in Connecticut ever year, from issues such as heart attacks and bronchitis. Since then, the state has made some efforts to clean up their act, but Hartford still measures pretty high on the list of most polluted cities in the US, and it’s not even at fault—it just happens to be downwind of all those coal and oil power plants in the Midwest.

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35. Houston, Texas

Everything is bigger in Texas—including pollution levels. Houston’s bad air comes from the unwelcome combination of car emissions and extremely hot weather, which condenses and holds smog so it sticks around the city instead of dissipating. On top of that, Houston residents have had to deal with some major environmental concerns, including two chemical plant fires in 2019 alone, which released a lethal mix of carbon monoxide, sulfur dioxide, toluene, and naphtha into the air.

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34. Indianapolis, Indiana

Over the last decade, Indianapolis’s air quality has just gotten worse, and the city’s officials don’t seem much interested in cleaning it up. The problem lies with nearby coal-burning power plants in Indiana, and the fact that Indianapolis, a major city with almost a million people, doesn’t have a public transit system. Therefore, everyone has to rely on cars to get around. And cars, as we all know, mean pollution. 

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33. Atlanta, Georgia

Anyone who’s visited Atlanta has probably noticed how the city sits inside a tangled bramble of freeways. This puzzle of roads, overpasses, and off-ramps is a nightmare to navigate but contains a big clue as to why Atlanta’s air is so polluted. If you guessed cars, you’re right. Tailpipe emissions are making the air as unhealthy as all-you-can-eat ribs, and not nearly as delicious.  

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32. Washington, D.C.

We could make a quippy comparison to how the air above Washington is as dirty as the politicians who work there, but the political and environmental reality is too depressing. DC is slowly being smothered in a layer of smog as thick as a badly coiffed head of hair that looks unnatural in some way that’s difficult to put a finger on. Where does it come from? Ironically, most of it can be traced back to coal.

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31. New York, New York

As the most populous city in the US, New York’s high-density population is a recipe for pollution. The city struggles to deal with garbage disposal and air pollution from all the traffic—from over 8 million people going about their everyday lives. Even worse, one of the contributors to the issue is sewage overflow. Yup, it’s exactly what you think it is. But at least the rats don’t seem to mind.

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30. San Francisco, California

The Bay Area’s ecosystem is still recovering from the impact of the Gold Rush back in the 19th century. Chemical testing of the water in the San Francisco Bay revealed high levels of mercury and other heavy metals that you don’t want to drink or swim in. Couple that with a high traffic shipping industry, and it spells bad news for one of the best food cities in the US.


29. Albuquerque, New Mexico

Last year, the wildfires in California were so bad that the smoke even reached New Mexico’s largest city. But smoke isn’t the only thing giving Albuquerque’s air a bad name. Railyards, asphalt companies, and bulk plants that store gasoline and diesel fuel are major contributors—not to mention the chemical sludge sprayed in the dry season to keep the dust problem down.

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28. Chico, California

Chico has been hit hard by California wildfires. The smoke is bad enough, but falling ash and soot has also contaminated the water supply, leading to a boil water advisory that residents are encouraged to follow.

abstract-art-blaze-bonfire-266526-300x200.jpgPhoto by Loe Moshkovska from Pexels

 27. Detroit, Michigan

If you’ve visited Detroit, you might be familiar with the funky smell that hangs over the city at times. That rotten egg odor comes from high concentrations of sulfur dioxide, just one of many icky chemicals in the air thanks to the oil refineries and steel mills around the city.

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26. Modesto, California

The Central Valley, where Modesto is located, has one of the most productive agricultural economies in the states. But the same industry keeping the rest of the country stocked with avocados and almonds has an unfortunate byproduct of bad quality air for Modesto residents.

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25. St. Louis, Missouri

Pollution is nothing new in St. Louis. The infamous 1939 St. Louis Smog incident occurred when sudden cold temperatures trapped smoke from coal-burning fires in the city’s air. The smog was so dense that it blocked out the sun, and the episode was so bad that the municipal government made major efforts to switch to clean-burning fuels (or cleaner, anyway.) Apparently, it wasn’t enough.


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24. Stockton, California

Though Stockton produces a lot of fruit and vegetable like asparagus, cherries, and tomatoes, the area’s fertility is one of the sources of its bad air quality. Agriculture is a major contributor due to crop burning, and so is shipping—you’ve got to get those tomatoes to other parts of the country somehow, and that means trucks that use diesel fuel. On top of that, Stockton is having an issue with water contaminates, leading environmentalists to warn that it’s in danger of becoming the next Flint.

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23. Yuba City, California

This city in Sutter County faces a pollution double whammy. Wildfire smoke has had a big impact on air quality, and rising temperatures and less rainfall suggest that the crisis will continue. On top of that, major plastics factories and industry giants like Coca Cola have been dumping waste into the Yuba River.


22. El Paso, Texas

Looks like it’s time to go back to riding on horses. Cars, which Texans use to get around the biggest state, create huge air quality problems. The city is creating incentives and running campaigns for people to use public transit, but so far this hasn’t made a dent in the brown fog that’s smothering El Paso.

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21. Philadelphia, Pennsylvania

Coal plants and diesel engines are the biggest offenders in the city of brotherly love. The particle pollution from these sources is dangerous since it can enter the bloodstream, triggering asthma attacks, strokes, and even lung cancer.

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20. Pittsburgh, Pennsylvania

Lots of industrial pollution is to blame for the fact that Pittsburgh has higher levels of cancer and asthma. Pittsburgh’s cold winters actually trap pollutants close to the ground—at nose level—and citizens even complain about the air smelling like rotten eggs. Yuck!

pittsburgh-4790389_1920-300x225.jpgImage by Christopher Klein from Pixabay

19. Madera, California

Central Valley, California, has a few contenders for most polluted city in the US, and Madera is one of them. Madera has an average of 47 unhealthy smog days and 25 unhealthy soot days each year, and none of that pollution is leaving the valley anytime soon.

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18. Chicago, Illinois

The source of the smog over Chicago has an easily traceable source. The city has a high concentration of coal-burning power plants, and coal is one of the worst enemies to air quality. Couple that with lots of industry relying on diesel engines, and you end up with a polluted brew.

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17. Las Cruces, New Mexico

The air in Las Cruces is hard to breathe due to cars, factories, and… dust? That’s right, but the dust we’re talking about can’t be taken care of with a Swiffer. Due to climate change and diminishing rains, New Mexico has been experiencing an increase in dust storms. And air full of dust is not the kind of air you want to be breathing.

people-walking-on-desert-on-a-windy-day-with-dust-clouding-3046299-300x200.jpgPhoto by Ricardo Esquivel from Pexels

16. Las Vegas, Nevada

The desert comes with its own set of environmental idiosyncracies. Pollution-wise, one of the major factors in Nevada is drought. Similar to California, Nevada has been experiencing a serious drought. Without any rain to wash the air clean, the city of sin has some crummy air quality going on of late.

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15. Sacramento, California

Smoke from the scourge of wildfires in California recently all seem to collect over Sacramento. The high temperatures don’t help; in the summer, the mercury can go up to 105 degrees several days a year. 

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14. Salt Lake City, Utah

Cars and trucks are pumping Utah’s skies full of smog, contributing to Salt Lake City’s position as one of the most polluted cities in the US. It also doesn’t help that many homes still have wood-burning stoves and fireplaces, which people use as their main source of heating in the winter. Wood smoke releases particle pollution that Utah’s mountains and valleys keep trapped through the winter.

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13. El Centro, California

This city on the US-Mexico border is so polluted that kids with asthma frequently wind up in the emergency room because of it. The surrounding area is primarily agricultural, and seasonal crop burning contributes to much of the haze hanging over El Centro.

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12. Denver, Colorado

Denver is a fast-growing city, which means that construction adds to the usual suspects making the air unclean to breathe. Also, it seems that Colorado is one of the worst violators of federal air quality laws. So much for its squeaky clean image.


11. San Diego, California

San Diego has always been a major port city, and it’s suffering the consequences. Massive amounts of soot in the air are trapped there by the surrounding mountains. However, San Diego is taking aggressive measures to combat the dirty air by expanding the public transit system and encouraging people to turn to zero-emission transportation options.

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10. Hanford, California

Hanford is home to a decommissioned nuclear production facility, so the fact that it’s now a contaminated wasteland is kind of unsurprising. Radioactive waste leaked into the river and the surrounding ground, creating toxic levels of radioactive materials in the water. So if you were thinking of visiting Hanford in the next 10 billion years, maybe think again?

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9. Payson, Arizona

Like Pheonix, nearby Payson is the opposite of an oasis in the Arizona desert, and the air has heavy levels of ozone. Experts report that “breathing in ozone at ground level can produce inflammation similar to a sunburn in the lungs, which can lead to permanent damage to lung tissue or cause issues to the respiratory system.” (source) Yikes.

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8. Fresno, California

Despite all its environmental laws, Big Oil and Big Agro still have a strong hold on California. Fresno has a lot of farms and a lot of oil fields, so it’s no surprise it makes the list of most polluted cities in the US. So much for being America’s Fertile Valley.

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7. Phoenix, Arizona

Phoenix is a big city sprawled out across the desert. As a result, most residents use a car to get around. This, in turn, contributes to some of the highest ozone levels in the country. Ozone is what happens when emissions like nitrogen and carbon monoxide mix with sunlight, which Arizona gets a lot of.

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6. Visalia, California

Cars, power plants, industrial boilers are the biggest culprits for why the air hanging over Visalia is so polluted. Soaring temperature averages and particle pollution from wildfires also play their part in this unhealthy mix. With little progress being made on climate change, California suffers from being the state with the highest number of most polluted cities in the US.


5. Bakersfield, California

Bad air in Bakersfield is pretty much stuck there thanks to its position in Central Valley. The city’s air quality problem is brought on primarily by the agriculture industry, traffic, and the oil industry. Because of this, the levels of soot and ozone in the hazy air are some of the highest in the country.


4. Hilo, Hawaii

Geographically, Hilo has bad luck. It’s the city closest to the volcanic activity on Hawaii, and the city is frequently under a veil of volcanic smog. Charmingly nicknamed “vog,” this particular brand of mugginess is created when sulfur dioxide mixes with the surrounding air, dust, and sunlight, and poses a risk to anyone with respiratory troubles.  


3. Riverside, California

Most people have never heard of Riverside. It’s a small suburb in California that, unfortunately, gets its bad air through no fault of its own. Winds pushing pollutants from LA inland mean this area suffers from worse pollution than it produces. The one positive side effect, if you can call it that, is that it’s one of the cheapest places to live and travel to in California.


2. Flint, Michigan

No matter how bad the air pollution is in the rest of the country, it can’t compare to the human toll that water contamination has had in Flint. An ongoing problem since 2014, toxic levels of lead in the Flint River thanks to factory dumping makes the groundwater undrinkable, hampering the lives of the locals in countless ways. 

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1. Los Angeles, California

LA still has the worst smog in the country. Sure, it might be the cause of the city’s glorious sunsets, but it’s also pretty bad for your lungs. Traffic, the shipping industry, and factories cause Los Angeles to have 145 days of unhealthy air quality out of the year, and it doesn’t stop there; smog from LA spreads all over the county, to Long Beach and even Disney World.

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