The 10 US cities with the worst air pollution in 2023 got a big boost from wildfires, with pollution levels well above maximum safe levels, according to a new study.
But major cities like New York City, Los Angeles and Chicago, places that many people associate with low air quality, were nowhere in the top 10 in the world, let alone the country.
In its annual study of the world’s worst air pollution cities, Swiss air technology company IQAir found that more than 1,000 US cities experienced air pollution levels many times higher than the international standard for poor air quality.
This threshold is the World Health Organization (WHO) guideline for the type of air pollution considered most dangerous to human health: particles smaller than 2.5 microns.
Here’s the list of the 10 most air-polluted cities in the US for 2023, according to IQAir’s dimensions at a reported 7,800 measurement locations worldwide:
- 1. Coraopolis, PA
- Forest Park, Georgia
- Cave Junction, OR
- Happy Camp, CA
- Adrian, MI
- Claymont, DE
- Robesonia, PA
- Attleboro, MA
- Elwood, Illinois
- Huntington, IN
These cities had the highest average air levels of 2.5 micron particles or aerosols, also known as PM2.5.
This type of air pollution comes from cars, coal-fired power stations and the burning of waste; general activities around the world, wherever you live.
According to the WHO, a ‘safe’ amount of PM2.5 is an average exposure of 0-5 micrograms per cubic meter of air per year.
But the top 10 most air-polluted cities in the US in 2023 all produced 15-20 micrograms per cubic meter.
What makes these cities so dirty?
In addition to cars and coal, PM2.5 can also come from burning wood, and according to IQAir, the massive spike in air pollution in the US in 2023 was due to the wildfires that raged for months in Canada.
The resulting smoke that swept across the United States exposed the average person to 66 percent more fine particle pollution than the previous record year in 2021.
Coraopalis, Pennsylvania, was found to be the most polluted city in the US in 2023. But it is mainly the fault of the Canadian forest fires, as the
Cave Junction, Oregon, the third most polluted city in the US, also had a fluke, peaking from 9.7 micrograms of PM2.5 per cubic meter in 2022 to 17.1 in 2023.
In most cases there is nothing special about these cities.
Coraopolis, Pennsylvania, for example, measured an average of 19.3 micrograms of PM2.5 per cubic meter in 2023, according to IQAir measurements.
But these pollution levels do not reflect the typical air in Coraopalis, which was only 7.2 in 2022.
Much of this came from September, when levels reached 42.1, and October, when they reached a stifling 54.2.
And it’s the same story for the other cities on this list: pollution levels peaked in 2023, especially in the summer and fall, matching Canadian wildfires.
Cave Junction, Oregon, the third most polluted city in the US, also had a fluke, peaking from 9.7 micrograms of PM2.5 per cubic meter in 2022 to 17.1 in 2023.
Claymont, Delaware was the sixth most polluted city in the US in 2023, according to IQAir. Despite a summer spike that corresponded with the wildfires, 2023 was no fluke.
Forest Park, Georgia, the second most air-polluted city in the US in 2023, had similarly poor ratings in 2022 and 2021. It is part of greater Atlanta and is home to a criss-cross tapestry of clogged highways.
In other cases, 2023 was not a one-off.
For example, Claymont, Delaware, was the sixth most polluted city in the US in 2023, according to IQAir. Despite a summer spike that corresponded with the wildfires, 2023 was no fluke.
In 2023, the average PM2.5 concentration was 16.5, only a slight increase from 16.4 in 2022 and even a decrease from 16.7 in 2021.
For Claymont, the culprit has already been identified: highways.
The I-495 and I-95 highways run through it and emit so much air pollution that a one-time spike was barely registered.
Regardless of their source, PM2.5 clouds are just the right size to lodge in your lungs and infiltrate the bloodstream, making them particularly concerning from a public health perspective.
Adrian, Michigan, the fifth most polluted city in the US in 2023, was only slightly worse off that year than the year before.
According to the WHO, outdoor air pollution is estimated to cause more than 4 million premature deaths worldwide every year.
Exposure to high concentrations of particulate matter, even for relatively short periods of 24 hours, can be harmfulThis was reported by the California Air Resources Board.
These aerosols can contribute to respiratory diseases such as asthma and bronchitis, and increase the chance that someone will need to go to the hospital for heart or lung conditions.
Exposure to these nanoparticles has even been linked to dementia and cognitive decline.
The US scored favorably when it comes to air quality: out of 134 countries, the country was ranked 102nd dirtiest in the world.
But that’s just a national average, and someone in Delaware can’t breathe Montana air.
So for anyone looking for the least polluted air, here are the rankings from IQAir’s data:
- Makawao, Hawaii
- Telluride, CO
- Tulalip, Washington
- Homer, Alaska
- Waimea, Hawaii
- Koloa, Hawaii
- Kihei, Hawaii
- Bayfield, Colorado
Keen readers will see a pattern.