Data / Rankings / Median Air Quality Index (US EPA) / Counties in Oregon

Counties in Oregon by median Air Quality Index (US EPA)

Lane County had the highest median Air Quality Index (US EPA) of 24 counties in 2010, at 47. Benton County had the lowest, at 20. The median was 33. Source: the U.S. Environmental Protection Agency.

Keep it in a collection in your library.
Highest47Lane County
Lowest20Benton County
Median3324 counties

Map of counties, 2010

Baker County: 33 indexBenton County: 20 indexClackamas County: 27 indexColumbia County: 29 indexCrook County: 27 indexDeschutes County: 34 indexDouglas County: 28 indexGrant County: 33 indexHarney County: 33 indexJackson County: 39 indexJefferson County: 33 indexJosephine County: 29 indexKlamath County: 35 indexLake County: 28 indexLane County: 47 indexLinn County: 34 indexMarion County: 31 indexMultnomah County: 36 indexUmatilla County: 40 indexUnion County: 33 indexWallowa County: 26 indexWasco County: 25 indexWashington County: 33 indexYamhill County: 21 index
  • Under 27
  • 27 to 29
  • 29 to 33
  • 33 to 34
  • 34 and over
  • No data
index, 2010. Hatched areas have no value for this period. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2010

Lane County: 47 indexLane County47Umatilla County: 40 indexUmatilla County40Jackson County: 39 indexJackson County39Multnomah County: 36 indexMultnomah County36Klamath County: 35 indexKlamath County35Deschutes County: 34 indexDeschutes County34Linn County: 34 indexLinn County34Baker County: 33 indexBaker County33Grant County: 33 indexGrant County33Harney County: 33 indexHarney County33Jefferson County: 33 indexJefferson County33Union County: 33 indexUnion County33Washington County: 33 indexWashington County33Marion County: 31 indexMarion County31Columbia County: 29 indexColumbia County29Josephine County: 29 indexJosephine County29Douglas County: 28 indexDouglas County28Lake County: 28 indexLake County28Clackamas County: 27 indexClackamas County27Crook County: 27 indexCrook County27Wallowa County: 26 indexWallowa County26Wasco County: 25 indexWasco County25Yamhill County: 21 indexYamhill County21Benton County: 20 indexBenton County20Lane County: 47 indexLane County47Umatilla County: 40 indexUmatilla County40Jackson County: 39 indexJackson County39Multnomah County: 36 indexMultnomah County36Klamath County: 35 indexKlamath County35Deschutes County: 34 indexDeschutes County34Linn County: 34 indexLinn County34Baker County: 33 indexBaker County33Grant County: 33 indexGrant County33Harney County: 33 indexHarney County33Jefferson County: 33 indexJefferson County33Union County: 33 indexUnion County33Washington County: 33 indexWashington County33Marion County: 31 indexMarion County31Columbia County: 29 indexColumbia County29Josephine County: 29 indexJosephine County29Douglas County: 28 indexDouglas County28Lake County: 28 indexLake County28Clackamas County: 27 indexClackamas County27Crook County: 27 indexCrook County27Wallowa County: 26 indexWallowa County26Wasco County: 25 indexWasco County25Yamhill County: 21 indexYamhill County21Benton County: 20 indexBenton County20
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2010
index		Change on 2009
1Lane County47-5
2Umatilla County40-2
3Jackson County39-6
4Multnomah County36-7
5Klamath County35-17
6Deschutes County34-1
6Linn County34-10
8Baker County33-6
8Grant County33-6
8Harney County33-6
8Jefferson County33-4
8Union County33-3
8Washington County33-7
14Marion County31-5
15Columbia County29-5
15Josephine County29-8
17Douglas County28-9
17Lake County28-6
19Clackamas County27-5
19Crook County27-9
21Wallowa County26-5
22Wasco County25-5
23Yamhill County21-3
24Benton County20-6

Other periods

About this ranking

Median of the daily Air Quality Index (AQI) values of a US county over the days of the year with an AQI, from the EPA AirData annual summaries.

More on how it is measured
  • The daily county AQI is the highest AQI among the monitors and pollutants reported that day (ozone, PM2.5, PM10, carbon monoxide and nitrogen dioxide).
  • Lower is cleaner: 0 to 50 is good, 51 to 100 moderate and above 100 unhealthy for sensitive groups.

United States counties with air quality monitors only, about 1,000 of some 3,100 in recent years; a county without monitors has no value. The number of days with an AQI differs between counties because some monitors run only in the ozone season.

Every value in the ranking comes from the same publisher and the same period, so the counties are compared on one definition. 2 counties with data in other periods have no value for 2010 and are left out rather than filled from another source. Equal values share a rank.

How to cite

U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.

Citation styles

The publisher is the author. Invokely is named only as the place the figures were read, where a style asks for it.

APA 7

U.S. Environmental Protection Agency. (2026). EPA AirData annual AQI by county: median daily AQI (Counties in Oregon by median Air Quality Index (US EPA), 2010) [Data set]. Retrieved October 12, 2026, from https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual

MLA 9

EPA AirData annual AQI by county: median daily AQI, Counties in Oregon by median Air Quality Index (US EPA), 2010. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/median-air-quality-index/oregon-counties?period=2010. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Counties in Oregon by median Air Quality Index (US EPA), 2010. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/median-air-quality-index/oregon-counties?period=2010.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Counties in Oregon by median Air Quality Index (US EPA), 2010 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/median-air-quality-index/oregon-counties?period=2010 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_oregon_by_2010,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Counties in Oregon by median Air Quality Index (US EPA), 2010}},
  year = {2026},
  howpublished = {Data set},
  url = {https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual},
  urldate = {2026-10-12},
  note = {Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/oregon-counties?period=2010. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. https://aqs.epa.gov/aqsweb/airdata/download\_files.html\#Annual. Retrieved 2026-10-12.},
}
RIS
TY  - DATA
AU  - U.S. Environmental Protection Agency
TI  - EPA AirData annual AQI by county: median daily AQI: Counties in Oregon by median Air Quality Index (US EPA), 2010
PY  - 2026
DA  - 2026/07/13
PB  - U.S. Environmental Protection Agency
DB  - Invokely
UR  - https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual
L2  - https://invokely.ai/rankings/median-air-quality-index/oregon-counties?period=2010
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/oregon-counties?period=2010.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
ER  -
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Rank Counties in Oregon by median Air Quality Index (US EPA) using official data, and cite the source.
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Questions

Which county has the highest median Air Quality Index (US EPA)?

Lane County, with 47 in 2010, according to the U.S. Environmental Protection Agency.

Which county has the lowest median Air Quality Index (US EPA)?

Benton County, with 20 in 2010.

Where does this ranking come from?

Every value comes from one source and one period, so the places are comparable: U.S. Environmental Protection Agency, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12. 2 counties have no value for 2010 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Oregon: more rankings