The "Crown" episode "Act of God" recreated for viewers the Great Smog of London, a catastrophic fog of polluted air that settled over the city in the winter of 1952. Sometimes called the Big Smoke, a dense cloud of coal-choked air turned day to night and killed thousands. An almost identical event had already occurred in 1948, in Donora, Pennsylvania. Home to the Donora Zinc Works, Donora was consumed by a dense smog filled with airborne pollutants released during zinc smelting. When the same unusual weather patterns that caused the disaster in Donora materialized in London, scientists knew what was coming but it was too late to act.
Following other tragedies in New York and the smoggiest day on record in Los Angeles, the U.S. government passed the Air Pollution Control Act of 1955—the predecessor of the Clean Air Acts. Nixon's administration established the Environmental Protection Agency in 1970 with the mission of enforcing regulations, collaborating with other organizations and sponsors, and educating the public about the hazards of pollution. The EPA has been successful in improving air quality in places like Donora.
Burning fossil fuels is the primary cause of both air pollution and climate change, but wildfires—most of which are human-caused—also lead to poor air quality. In the summer of 2025, the Garnet Fire led to hazy, smoky air in parts of California, while weeks earlier, hundreds of wildfires burning in Canada significantly worsened pollution in the U.S. Midwest and Northeast. And beyond merely being an annoyance, wildfire smoke can have deadly consequences. A study published in Nature in September 2025 found that toxic particles carried by smoke from the 2023 Canadian wildfires caused a stunning 82,000 deaths worldwide.
In the interest of finding other places in the country with the dirtiest air, Stacker compiled a list of the metro areas with the worst air pollution in the U.S. using the 2022 American Lung Association's State of the Air Report.
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1 / 26- Annual particle pollution: #25 most polluted metropolitan area
- High 24-hour particle pollution days: Not ranked in top 24 most polluted metropolitan areas
- High ozone days: Not ranked in top 25 most polluted metropolitan areas
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2 / 26- Annual particle pollution: #25 most polluted metropolitan area
- High 24-hour particle pollution days: Not ranked in top 24 most polluted metropolitan areas
- High ozone days: Not ranked in top 25 most polluted metropolitan areas
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3 / 26- Annual particle pollution: #24 most polluted metropolitan area
- High 24-hour particle pollution days: Not ranked in top 24 most polluted metropolitan areas
- High ozone days: Not ranked in top 25 most polluted metropolitan areas
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4 / 26- Annual particle pollution: #22 most polluted metropolitan area
- High 24-hour particle pollution days: Not ranked in top 24 most polluted metropolitan areas
- High ozone days: #16 most polluted metropolitan area
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5 / 26- Annual particle pollution: #22 most polluted metropolitan area
- High 24-hour particle pollution days: Not ranked in top 24 most polluted metropolitan areas
- High ozone days: #8 most polluted metropolitan area
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6 / 26- Annual particle pollution: #21 most polluted metropolitan area
- High 24-hour particle pollution days: #9 most polluted metropolitan area
- High ozone days: Not ranked in top 25 most polluted metropolitan areas
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7 / 26- Annual particle pollution: #18 most polluted metropolitan area
- High 24-hour particle pollution days: Not ranked in top 24 most polluted metropolitan areas
- High ozone days: Not ranked in top 25 most polluted metropolitan areas
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8 / 26- Annual particle pollution: #18 most polluted metropolitan area
- High 24-hour particle pollution days: Not ranked in top 24 most polluted metropolitan areas
- High ozone days: Not ranked in top 25 most polluted metropolitan areas
Sean Pavone // Shutterstock
9 / 26- Annual particle pollution: #18 most polluted metropolitan area
- High 24-hour particle pollution days: #15 most polluted metropolitan area
- High ozone days: Not ranked in top 25 most polluted metropolitan areas
Canva
10 / 26- Annual particle pollution: #16 most polluted metropolitan area
- High 24-hour particle pollution days: Not ranked in top 24 most polluted metropolitan areas
- High ozone days: #24 most polluted metropolitan area
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11 / 26- Annual particle pollution: #16 most polluted metropolitan area
- High 24-hour particle pollution days: #5 most polluted metropolitan area
- High ozone days: #23 most polluted metropolitan area
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12 / 26- Annual particle pollution: #15 most polluted metropolitan area
- High 24-hour particle pollution days: Not ranked in top 24 most polluted metropolitan areas
- High ozone days: Not ranked in top 25 most polluted metropolitan areas
ESB Professional // Shutterstock
13 / 26- Annual particle pollution: #14 most polluted metropolitan area
- High 24-hour particle pollution days: #22 most polluted metropolitan area
- High ozone days: Not ranked in top 25 most polluted metropolitan areas
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14 / 26- Annual particle pollution: #13 most polluted metropolitan area
- High 24-hour particle pollution days: Not ranked in top 24 most polluted metropolitan areas
- High ozone days: Not ranked in top 25 most polluted metropolitan areas
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15 / 26- Annual particle pollution: #12 most polluted metropolitan area
- High 24-hour particle pollution days: Not ranked in top 24 most polluted metropolitan areas
- High ozone days: Not ranked in top 25 most polluted metropolitan areas
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16 / 26- Annual particle pollution: #11 most polluted metropolitan area
- High 24-hour particle pollution days: #7 most polluted metropolitan area
- High ozone days: #9 most polluted metropolitan area
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17 / 26- Annual particle pollution: #10 most polluted metropolitan area
- High 24-hour particle pollution days: Not ranked in top 24 most polluted metropolitan areas
- High ozone days: #15 most polluted metropolitan area
MARELBU // Wikimedia Commons
18 / 26- Annual particle pollution: #9 most polluted metropolitan area
- High 24-hour particle pollution days: #6 most polluted metropolitan area
- High ozone days: #20 most polluted metropolitan area
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19 / 26- Annual particle pollution: #8 most polluted metropolitan area
- High 24-hour particle pollution days: #11 most polluted metropolitan area
- High ozone days: #5 most polluted metropolitan area
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20 / 26- Annual particle pollution: #7 most polluted metropolitan area
- High 24-hour particle pollution days: #3 most polluted metropolitan area
- High ozone days: Not ranked in top 25 most polluted metropolitan areas
Ahturner // Shutterstock
21 / 26- Annual particle pollution: #6 most polluted metropolitan area
- High 24-hour particle pollution days: #21 most polluted metropolitan area
- High ozone days: Not ranked in top 25 most polluted metropolitan areas
Canva
22 / 26- Annual particle pollution: #5 most polluted metropolitan area
- High 24-hour particle pollution days: #8 most polluted metropolitan area
- High ozone days: #1 most polluted metropolitan area
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23 / 26- Annual particle pollution: #4 most polluted metropolitan area
- High 24-hour particle pollution days: #4 most polluted metropolitan area
- High ozone days: #13 most polluted metropolitan area
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24 / 26- Annual particle pollution: #2 most polluted metropolitan area
- High 24-hour particle pollution days: #1 most polluted metropolitan area
- High ozone days: #4 most polluted metropolitan area
Jacob Boomsma // Shutterstock
25 / 26- Annual particle pollution: #2 most polluted metropolitan area
- High 24-hour particle pollution days: #9 most polluted metropolitan area
- High ozone days: #3 most polluted metropolitan area
Canva
26 / 26- Annual particle pollution: #1 most polluted metropolitan area
- High 24-hour particle pollution days: #2 most polluted metropolitan area
- High ozone days: #2 most polluted metropolitan area
