Data / Rankings / Share of days with good air quality (US EPA AQI) / Counties in Oregon

Counties in Oregon by share of days with good air quality (US EPA AQI)

Columbia County had the highest share of days with good air quality (US EPA AQI) of 24 counties in 2010, at 95.3%. Lane County had the lowest, at 55.3%. The median was 77%. Source: EPA.

Keep it in a collection in your library.
Highest95.3Columbia County
Lowest55.3Lane County
Median7724 counties

Map of counties, 2010

Baker County: 75 %Benton County: 90.9 %Clackamas County: 94.8 %Columbia County: 95.3 %Crook County: 77.4 %Deschutes County: 89.9 %Douglas County: 87.1 %Grant County: 66.3 %Harney County: 62.3 %Jackson County: 71.8 %Jefferson County: 71.5 %Josephine County: 78.6 %Klamath County: 63.1 %Lake County: 76.6 %Lane County: 55.3 %Linn County: 61.6 %Marion County: 79.7 %Multnomah County: 77.5 %Umatilla County: 67.1 %Union County: 71.5 %Wallowa County: 80.9 %Wasco County: 80.5 %Washington County: 76.2 %Yamhill County: 93.4 %
  • Under 67
  • 67 to 75
  • 75 to 78
  • 78 to 88
  • 88 and over
  • No data
%, 2010. Hatched areas have no value for this period. Source: Invokely calculation with data from EPA. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2010

Columbia County: 95.3 %Columbia County95.3Clackamas County: 94.8 %Clackamas County94.8Yamhill County: 93.4 %Yamhill County93.4Benton County: 90.9 %Benton County90.9Deschutes County: 89.9 %Deschutes County89.9Douglas County: 87.1 %Douglas County87.1Wallowa County: 80.9 %Wallowa County80.9Wasco County: 80.5 %Wasco County80.5Marion County: 79.7 %Marion County79.7Josephine County: 78.6 %Josephine County78.6Multnomah County: 77.5 %Multnomah County77.5Crook County: 77.4 %Crook County77.4Lake County: 76.6 %Lake County76.6Washington County: 76.2 %Washington County76.2Baker County: 75 %Baker County75Jackson County: 71.8 %Jackson County71.8Jefferson County: 71.5 %Jefferson County71.5Union County: 71.5 %Union County71.5Umatilla County: 67.1 %Umatilla County67.1Grant County: 66.3 %Grant County66.3Klamath County: 63.1 %Klamath County63.1Harney County: 62.3 %Harney County62.3Linn County: 61.6 %Linn County61.6Lane County: 55.3 %Lane County55.3Columbia County: 95.3 %Columbia County95.3Clackamas County: 94.8 %Clackamas County94.8Yamhill County: 93.4 %Yamhill County93.4Benton County: 90.9 %Benton County90.9Deschutes County: 89.9 %Deschutes County89.9Douglas County: 87.1 %Douglas County87.1Wallowa County: 80.9 %Wallowa County80.9Wasco County: 80.5 %Wasco County80.5Marion County: 79.7 %Marion County79.7Josephine County: 78.6 %Josephine County78.6Multnomah County: 77.5 %Multnomah County77.5Crook County: 77.4 %Crook County77.4Lake County: 76.6 %Lake County76.6Washington County: 76.2 %Washington County76.2Baker County: 75 %Baker County75Jackson County: 71.8 %Jackson County71.8Jefferson County: 71.5 %Jefferson County71.5Union County: 71.5 %Union County71.5Umatilla County: 67.1 %Umatilla County67.1Grant County: 66.3 %Grant County66.3Klamath County: 63.1 %Klamath County63.1Harney County: 62.3 %Harney County62.3Linn County: 61.6 %Linn County61.6Lane County: 55.3 %Lane County55.3
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2010 (%)Change on 2009
1Columbia County95.3+12.8 pts
2Clackamas County94.8+10.4 pts
3Yamhill County93.4+6.2 pts
4Benton County90.9+10.4 pts
5Deschutes County89.9+5.3 pts
6Douglas County87.1+13.8 pts
7Wallowa County80.9+2.1 pts
8Wasco County80.5+4.6 pts
9Marion County79.7+7.4 pts
10Josephine County78.6+14.2 pts
11Multnomah County77.5+14.2 pts
12Crook County77.4+14.9 pts
13Lake County76.6+8.8 pts
14Washington County76.2+14.8 pts
15Baker County75+7.4 pts
16Jackson County71.8+12.3 pts
17Jefferson County71.5+2.7 pts
17Union County71.5+2.2 pts
19Umatilla County67.1+3 pts
20Grant County66.3+6.8 pts
21Klamath County63.1+15.3 pts
22Harney County62.3+2.9 pts
23Linn County61.6+6.3 pts
24Lane County55.3+11.5 pts

Other periods

About this ranking

Days with a daily Air Quality Index of 0 to 50 (good) as a percentage of the days of the year with an AQI in a US county. Calculated by Invokely from the day counts in the EPA AirData annual summaries; both counts are stored with each value.

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: good days as a share of days with an AQI, calculated with stored counts. 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: good days as a share of days with an AQI, calculated with stored counts (Counties in Oregon by share of days with good air quality (US EPA AQI), 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: good days as a share of days with an AQI, calculated with stored counts, Counties in Oregon by share of days with good air quality (US EPA AQI), 2010. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/good-air-quality-days-share/oregon-counties?period=2010. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. Counties in Oregon by share of days with good air quality (US EPA AQI), 2010. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/good-air-quality-days-share/oregon-counties?period=2010.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts, Counties in Oregon by share of days with good air quality (US EPA AQI), 2010 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/good-air-quality-days-share/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: good days as a share of days with an AQI, calculated with stored counts: Counties in Oregon by share of days with good air quality (US EPA AQI), 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/good-air-quality-days-share/oregon-counties?period=2010. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. 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: good days as a share of days with an AQI, calculated with stored counts: Counties in Oregon by share of days with good air quality (US EPA AQI), 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/good-air-quality-days-share/oregon-counties?period=2010
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/oregon-counties?period=2010.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
ER  -
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Questions

Which county has the highest share of days with good air quality (US EPA AQI)?

Columbia County, with 95.3% in 2010, according to EPA.

Which county has the lowest share of days with good air quality (US EPA AQI)?

Lane County, with 55.3% 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: good days as a share of days with an AQI, calculated with stored counts. Retrieved 2026-10-12. 2 counties have no value for 2010 and are not ranked.

Share of days with good air quality (US EPA AQI): other rankings

Counties in Oregon: more rankings