As reported by OPB, over the past five years, wildfires have scorched more than 36 million acres of land across the United States. But the destruction extends far beyond the burn zones—wildfire smoke travels hundreds, sometimes thousands, of miles, impacting millions of people downwind.
Just ask residents of Medford, Grants Pass, and Bend—ranked as the top three smokiest cities in the nation between 2019 and 2023.
A research team led by Dan Jaffe and Haebum Lee at the University of Washington Bothell has developed a new method to rapidly assess the number of days communities experienced elevated levels of wildfire smoke. Their approach combines particulate readings from ground-based air quality monitors with satellite imagery to provide a clearer picture of smoke exposure.
Oregon cities dominated the top 10 list, with Klamath Falls (#5), Roseburg (#6), and Eugene/Springfield (#10) joining Medford, Grants Pass, and Bend. Meanwhile, Yakima ranked as the smokiest city in Washington at #15.
Particulate pollution stems from multiple sources, including vehicle emissions, power plants, industrial processes, wood stoves, and agricultural activity. However, in these wildfire-prone cities, at least 30% of the annual particulate matter (PM 2.5) came directly from wildfire smoke.
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These microscopic particulates are so small that they can penetrate deep into the lungs and enter the bloodstream, increasing the risk of respiratory illnesses, heart attacks, and strokes. To better understand the health impacts, researchers analyzed emergency room visits for asthma-related issues. Between 2019 and 2023, an estimated 42,500 ER visits were linked to wildfire smoke exposure.
Although smaller cities in the West bore the brunt of prolonged smoke exposure, high-population metro areas in the Eastern U.S. saw the highest total number of smoke-related ER visits. In Portland and Seattle, approximately 15% of all asthma-related emergency visits during this period were attributed to wildfire smoke.
The findings were recently presented at the American Geophysical Union annual meeting in Washington, D.C.
