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Air quality in Oregon

EPA monitors report from 23 of Oregon’s 36 counties. That is the honest limit of this page: the other 13 are not measured, not clean. In 2025 the most affected monitored county was Josephine County, with 8 days above the moderate category.

23
Counties with monitors
13
Counties without
28
Days above moderate, 2025
Summed across monitored counties
11.9%
Adults with asthma
Population-weighted county estimate

County by county

Monitored Oregon counties

GoodModerateUnhealthy for sensitive groupsUnhealthyVery unhealthyHazardous
County90th %ile AQIAbove moderateMax AQI2025 days by category
Josephine County678208
Lane County686153
Deschutes County523153
Klamath County693149
Clackamas County532119
Crook County652144
Jackson County672152
Lake County621105
Linn County571122
Baker County54085
Benton County52068
Columbia County45069
Douglas County62069
Grant County67089
Harney County60093
Jefferson County63090
Marion County58085
Multnomah County57087
Umatilla County64095
Union County54079
Wallowa County53088
Wasco County54081
Washington County57088

EPA Air Quality System annual summaries by county, 2025. The 90th percentile AQI describes a day worse than nine out of ten, which is a steadier measure than the annual maximum a single wildfire can set.

Not measured

13 counties without a monitor

No EPA monitor reported from these counties, so there is no air quality record to publish. Their radon zone is known, and radon is measured in the building rather than the air outside it.

Other states

Air quality elsewhere