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 25 counties in 2011, at 94.1%. Lane County had the lowest, at 57%. The median was 73.6%. Source: EPA.

Keep it in a collection in your library.
Highest94.1Clackamas County
Lowest57Lane County
Median73.625 counties

Map of counties, 2011

Baker County: 72.2 %Benton County: 80.3 %Clackamas County: 94.1 %Columbia County: 84.2 %Coos County: 91.1 %Crook County: 67.7 %Deschutes County: 80.5 %Douglas County: 79.4 %Grant County: 59.4 %Harney County: 60.1 %Jackson County: 63.6 %Jefferson County: 79.4 %Josephine County: 71.5 %Klamath County: 61.4 %Lake County: 72.5 %Lane County: 57 %Linn County: 62.8 %Marion County: 75.9 %Multnomah County: 71.2 %Umatilla County: 75.7 %Union County: 73.6 %Wallowa County: 84.5 %Wasco County: 85.8 %Washington County: 71.8 %Yamhill County: 90.1 %
  • Under 63
  • 63 to 72
  • 72 to 77
  • 77 to 84
  • 84 and over
  • No data
%, 2011. 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, 2011

Clackamas County: 94.1 %Clackamas County94.1Coos County: 91.1 %Coos County91.1Yamhill County: 90.1 %Yamhill County90.1Wasco County: 85.8 %Wasco County85.8Wallowa County: 84.5 %Wallowa County84.5Columbia County: 84.2 %Columbia County84.2Deschutes County: 80.5 %Deschutes County80.5Benton County: 80.3 %Benton County80.3Douglas County: 79.4 %Douglas County79.4Jefferson County: 79.4 %Jefferson County79.4Marion County: 75.9 %Marion County75.9Umatilla County: 75.7 %Umatilla County75.7Union County: 73.6 %Union County73.6Lake County: 72.5 %Lake County72.5Baker County: 72.2 %Baker County72.2Washington County: 71.8 %Washington County71.8Josephine County: 71.5 %Josephine County71.5Multnomah County: 71.2 %Multnomah County71.2Crook County: 67.7 %Crook County67.7Jackson County: 63.6 %Jackson County63.6Linn County: 62.8 %Linn County62.8Klamath County: 61.4 %Klamath County61.4Harney County: 60.1 %Harney County60.1Grant County: 59.4 %Grant County59.4Lane County: 57 %Lane County57Clackamas County: 94.1 %Clackamas County94.1Coos County: 91.1 %Coos County91.1Yamhill County: 90.1 %Yamhill County90.1Wasco County: 85.8 %Wasco County85.8Wallowa County: 84.5 %Wallowa County84.5Columbia County: 84.2 %Columbia County84.2Deschutes County: 80.5 %Deschutes County80.5Benton County: 80.3 %Benton County80.3Douglas County: 79.4 %Douglas County79.4Jefferson County: 79.4 %Jefferson County79.4Marion County: 75.9 %Marion County75.9Umatilla County: 75.7 %Umatilla County75.7Union County: 73.6 %Union County73.6Lake County: 72.5 %Lake County72.5Baker County: 72.2 %Baker County72.2Washington County: 71.8 %Washington County71.8Josephine County: 71.5 %Josephine County71.5Multnomah County: 71.2 %Multnomah County71.2Crook County: 67.7 %Crook County67.7Jackson County: 63.6 %Jackson County63.6Linn County: 62.8 %Linn County62.8Klamath County: 61.4 %Klamath County61.4Harney County: 60.1 %Harney County60.1Grant County: 59.4 %Grant County59.4Lane County: 57 %Lane County57
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2011 (%)Change on 2010
1Clackamas County94.1-0.7 pts
2Coos County91.1n/a
3Yamhill County90.1-3.3 pts
4Wasco County85.8+5.3 pts
5Wallowa County84.5+3.6 pts
6Columbia County84.2-11.1 pts
7Deschutes County80.5-9.4 pts
8Benton County80.3-10.6 pts
9Douglas County79.4-7.7 pts
9Jefferson County79.4+7.9 pts
11Marion County75.9-3.8 pts
12Umatilla County75.7+8.6 pts
13Union County73.6+2.1 pts
14Lake County72.5-4.1 pts
15Baker County72.2-2.8 pts
16Washington County71.8-4.4 pts
17Josephine County71.5-7.1 pts
18Multnomah County71.2-6.3 pts
19Crook County67.7-9.7 pts
20Jackson County63.6-8.2 pts
21Linn County62.8+1.2 pts
22Klamath County61.4-1.7 pts
23Harney County60.1-2.2 pts
24Grant County59.4-6.9 pts
25Lane County57+1.7 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. 1 counties with data in other periods have no value for 2011 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), 2011) [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), 2011. 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=2011. 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), 2011. 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=2011.

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), 2011 [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=2011 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_oregon_by_2011,
  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), 2011}},
  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=2011. 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), 2011
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=2011
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/oregon-counties?period=2011.
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  -
Embed this chart

Paste this code into a web page or a blog post. The chart shows the latest figures as they are published, with the source and a link back to this page.

Sites that read oEmbed links, such as WordPress, can show the chart when you paste the link to this page.

Use this data in your AI agent

Invokely serves this figure to AI assistants through MCP and to code through a REST API, with the source and citation attached. Ask your assistant:

Rank Counties in Oregon by share of days with good air quality (US EPA AQI) using official data, and cite the source.
rank_places {"indicator":"aqi_good_days_share","level":"province","within":"Oregon","limit":10}
GET https://invokely.ai/api/v1/rank?indicator=aqi_good_days_share&level=province&within=Oregon&limit=10

Connect Claude, ChatGPT or Cursor in one step. The trial answers 25 calls a day without an account.

Questions

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

Clackamas County, with 94.1% in 2011, according to EPA.

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

Lane County, with 57% in 2011.

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. 1 counties have no value for 2011 and are not ranked.

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

Counties in Oregon: more rankings