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DEQ recommends EPA designate all Idaho airsheds as meeting new particulate matter standards

February 4, 2025

Contact: Mary Anderson, Air Quality Bureau Chief, Mary.Anderson@deq.idaho.gov 

BOISE – The Idaho Department of Environmental Quality (DEQ) recommends that the U. S. Environmental Protection Agency (EPA) designate all Idaho airsheds as meeting new federal health standards for particulate matter (PM2.5).  

In 2024, EPA lowered the annual health-based National Ambient Air Quality Standards for PM2.5 from 12 µg/m3 to 9 µg/m3. Particulate matter are microscopic particles emitted from sources like wildfires, outdoor burning, woodstoves, and vehicles. These particles can penetrate deep into the lungs and enter the bloodstream, increasing the risk of heart disease, lung cancer, stroke, and other health conditions, especially for vulnerable groups. 

DEQ is recommending that EPA exclude wildfire smoke impacts that contribute to days with high PM2.5 concentrations, which would keep Idaho airsheds within the new national levels. Some wildfire events are considered “exceptional” and not representative of typical air quality conditions. EPA will review DEQ’s recommendation and finalize designations for Idaho based on the most recent data, most likely 2022-2024, by February 7, 2026.   

DEQ’s recommendation comes after Idaho communities have worked for years to improve air quality, including replacing old woodstoves, providing woodsheds and moisture meters to homeowners, and much more.  

DEQ’s recommendation letter is available here.

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