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)

Clackamas County had the highest share of days with good air quality (US EPA AQI) of 24 counties in 2019, at 95.1%. Harney County had the lowest, at 56%. The median was 73.7%. Source: EPA.

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Highest95.1Clackamas County
Lowest56Harney County
Median73.724 counties

Map of counties, 2019

Baker County: 81.4 %Benton County: 82.7 %Clackamas County: 95.1 %Columbia County: 94.2 %Coos County: 92.5 %Crook County: 72.9 %Deschutes County: 84.7 %Douglas County: 73.8 %Grant County: 58.7 %Harney County: 56 %Jackson County: 68.2 %Jefferson County: 71.5 %Josephine County: 68.8 %Klamath County: 63 %Lake County: 79.3 %Lane County: 59.2 %Linn County: 63.8 %Marion County: 73.6 %Multnomah County: 77.5 %Umatilla County: 73.2 %Union County: 85.8 %Wallowa County: 79.6 %Wasco County: 74.9 %Washington County: 73.4 %
  • Under 66
  • 66 to 73
  • 73 to 77
  • 77 to 84
  • 84 and over
  • No data
%, 2019. 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, 2019

Clackamas County: 95.1 %Clackamas County95.1Columbia County: 94.2 %Columbia County94.2Coos County: 92.5 %Coos County92.5Union County: 85.8 %Union County85.8Deschutes County: 84.7 %Deschutes County84.7Benton County: 82.7 %Benton County82.7Baker County: 81.4 %Baker County81.4Wallowa County: 79.6 %Wallowa County79.6Lake County: 79.3 %Lake County79.3Multnomah County: 77.5 %Multnomah County77.5Wasco County: 74.9 %Wasco County74.9Douglas County: 73.8 %Douglas County73.8Marion County: 73.6 %Marion County73.6Washington County: 73.4 %Washington County73.4Umatilla County: 73.2 %Umatilla County73.2Crook County: 72.9 %Crook County72.9Jefferson County: 71.5 %Jefferson County71.5Josephine County: 68.8 %Josephine County68.8Jackson County: 68.2 %Jackson County68.2Linn County: 63.8 %Linn County63.8Klamath County: 63 %Klamath County63Lane County: 59.2 %Lane County59.2Grant County: 58.7 %Grant County58.7Harney County: 56 %Harney County56Clackamas County: 95.1 %Clackamas County95.1Columbia County: 94.2 %Columbia County94.2Coos County: 92.5 %Coos County92.5Union County: 85.8 %Union County85.8Deschutes County: 84.7 %Deschutes County84.7Benton County: 82.7 %Benton County82.7Baker County: 81.4 %Baker County81.4Wallowa County: 79.6 %Wallowa County79.6Lake County: 79.3 %Lake County79.3Multnomah County: 77.5 %Multnomah County77.5Wasco County: 74.9 %Wasco County74.9Douglas County: 73.8 %Douglas County73.8Marion County: 73.6 %Marion County73.6Washington County: 73.4 %Washington County73.4Umatilla County: 73.2 %Umatilla County73.2Crook County: 72.9 %Crook County72.9Jefferson County: 71.5 %Jefferson County71.5Josephine County: 68.8 %Josephine County68.8Jackson County: 68.2 %Jackson County68.2Linn County: 63.8 %Linn County63.8Klamath County: 63 %Klamath County63Lane County: 59.2 %Lane County59.2Grant County: 58.7 %Grant County58.7Harney County: 56 %Harney County56
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2019 (%)Change on 2018
1Clackamas County95.1+13 pts
2Columbia County94.2+3.3 pts
3Coos County92.5n/a
4Union County85.8+7.9 pts
5Deschutes County84.7+9.5 pts
6Benton County82.7-3.8 pts
7Baker County81.4+2.7 pts
8Wallowa County79.6+3.3 pts
9Lake County79.3+11.1 pts
10Multnomah County77.5+3 pts
11Wasco County74.9-1.7 pts
12Douglas County73.8-2.4 pts
13Marion County73.6-1.5 pts
14Washington County73.4+2.2 pts
15Umatilla County73.2-4 pts
16Crook County72.9+3.8 pts
17Jefferson County71.5+19.3 pts
18Josephine County68.8+15.1 pts
19Jackson County68.2+16 pts
20Linn County63.8-5.8 pts
21Klamath County63+11.9 pts
22Lane County59.2+0.8 pts
23Grant County58.7+1.8 pts
24Harney County56-4.8 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 2019 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), 2019) [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), 2019. 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=2019. 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), 2019. 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=2019.

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), 2019 [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=2019 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_oregon_by_2019,
  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), 2019}},
  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=2019. 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), 2019
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=2019
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/oregon-counties?period=2019.
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)?

Clackamas County, with 95.1% in 2019, according to EPA.

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

Harney County, with 56% in 2019.

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 2019 and are not ranked.

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

Counties in Oregon: more rankings