The smog and haze of pollution hanging over major cities like New York might lead people to believe they are the worst areas for maintaining healthy lungs.
But according to recent research, they would be wrong.
In fact, the most polluted places in the country dot the West Coast, including three in Oregon, two in California, and one each in Washington, Nevada, and Alaska.
Researchers from the University of Colorado School of Medicine built an algorithm that used imagery from satellites and measures of particulate matter (PM2.5) to zero in on air pollution caused by wildfire smoke, which blankets a region for days or even weeks at a time after a blaze breaks out.
PM2.5 particles, measured as micrograms per cubic meter (µg/m3), are small enough to invade the lungs and cause a myriad of health problems, from respiratory illness to cancer, and a recent analysis of data found a link between wildfires and dementia.
According to the research, the eight smokiest city in the US was Medford, Oregon, followed by Grants Pass and Bend, Oregon. Then came Gardenville-Rancho, Nevada; Bishop, California; Yakima, Washington; Fairbanks-College, Alaska; and the Sacramento Metropolitan Area in California.
Wildfires are common along the West Coast, though last year’s wildfire season descended on the East Coast as well, and they cloud the air with smoke, ash and other pollutants produced by the deadly flames.
The EPA suggests yearly exposure to this type of particulate matter should stay below 9 µg/m3, but with daily averages in some of the cities up to 3.4 µg/m3, lead researcher Dr Dan Jaffe said this exposure is ‘a very significant fraction’ of the EPA’s cut off.
Researchers from the University of Washington and George Washington University found that over the past five years, the cities most affected by air pollution from wildfires were mainly along the West Coast. However, in 2023, smoke from Canadian wildfires reached as far east as Baltimore, affecting cities in Wisconsin, Minnesota, New York, and DC
Three cities in Oregon (pictured) were designated the top spots for air pollution linked to wildfires
Wildfires typically rage along the dry, warm West Coast and are becoming more common with an increase in droughts and surge in high temperatures.
They bombard the lungs with tiny particles that raise the risk of heart disease, stroke, lung cancer, and early death.
Researchers determined between 2019 and 2023, the areas hardest hit by air pollution linked to wildfires were all along the West Coast.
Three cities in western Oregon were the smokiest on average over five years.
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Smoke doesn’t affect these cities every day, but when averaged out for the entire year, the smokiest cities in each Western state had daily averages of at least 2 µg/m3.
In Medford, Oregon, the city with the highest smoke levels, daily amounts of PM2.5 averaged 4.2 µg/m3 over one year.
In Gardenville-Rancho, Nevada the daily average was 3.4 µg/m3. It was 2.7 µg/m3 in Bishop, California; 2.5 µg/m3 in Yakima, Washington; and 2.3 µg/m3 micrograms per cubic meter in Fairbanks-College, Alaska.
The smokiest city with over a million residents is the Sacramento metropolitan area, where the annual daily PM2.5 level averaged 2 µg/m3.
In total, around 3.45 million residents of these cities have been exposed to unsafe levels of wildfire smoke.
Fire-related air pollution nearly doubled in the United States in 2023 following the worst wildfires in Canadian history this summer
Blazes scorched 42.7 million acres of land in Canada due to out of control fires in 2023, blanketing much of the US in smog
The researchers could not say why certain cities' air quality was worse than others, including those that are more likely than rural areas to suffer severe air pollution.
But wildfire smoke has wide reach - thousands of miles - and depending on atmospheric conditions, where it settles can seem random.
Measuring the impacts of wildfire on air quality and health is a labor-intensive process that involves analyzing satellite image data, weather patterns, and measurements of PM2.5 in the air.
To speed the process up, researchers developed an algorithm that could quickly sort through two sets of data collected between 2019 and 2023 containing satellite images of smoke and PM2.5 concentrations collected at ground level throughout the country.
The algorithm was trained to recognize smoke days from those data sets. The team then added heath data from hospitals in the most polluted cities to determine whether the smoke had an impact on emergency room visits during 'especially hazy days.'
The smokiest cities over the five-year study period were all in the western US, however, the extreme 2023 fire season saw smoke spread over usually spared cities.
While not high among the study's entire period, due to last year's extreme wildfire season, North Dakota, Minnesota and Wisconsin joined the list of smokiest spots.
Additionally, Baltimore saw its annual PM2.5 average rise from 0.7 µg/m3 to 2 µg/m3.
PM2.5 particles, measured as micrograms per cubic meter (µg/m3), are small enough to invade the lungs and cause a myriad of health problems
The researchers noted states outside the West Coast also saw an uptick in emergency department visits in 2023. For instance, they estimated around one-third of all PM2.5-related emergency room visits in Detroit during 2023 were due to smoke from Canadian wildfires that had spread south.
Within the researchers' study period, 2023 had the highest increase in emergency room visits related to wildfire smoke and the US saw an extra 16,000 emergency room visits.
Dr Jaffe, an environmental chemist at the University of Washington, said: ‘2023 was this strange year where the Canadian forests were just torched like crazy, and the Midwest got hit extremely hard.
‘For cities and towns, I think it’s important to be planning ahead and thinking about what’s a normal year, and what’s an extreme year.’
And he told Newsweek: 'While wildfire smoke happens every year and impacts some communities, our research tells us which communities are consistently most impacted and therefore which communities should be doing the most to plan ahead for smoke.'