Data / Share of days with good air quality (US EPA AQI) / San Juan County

Share of days with good air quality (US EPA AQI) in San Juan County

Share of days with good air quality (US EPA AQI) in San Juan County was 99.1% in 2019, according to EPA.

201999.1%

Next release: Tuesday, 13 July 2027, estimated by Invokely from past publication dates (low confidence), not announced by the publisher. Release calendar

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Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

All 1 values
Period%
201999.1

San Juan County compared with nearby places

Adams County: 94.2 %Asotin County: 70 %Benton County: 75 %Chelan County: 70.7 %Clallam County: 78.1 %Clark County: 76.1 %Columbia County: 88.2 %Cowlitz County: 83.6 %Franklin County: 86.5 %Garfield County: 92.2 %Grant County: 83.8 %Grays Harbor County: 92.9 %Jefferson County: 94.2 %King County: 57 %Kitsap County: 92.1 %Kittitas County: 73.4 %Klickitat County: 82.2 %Lewis County: 84.4 %Mason County: 84.5 %Okanogan County: 57.3 %Pierce County: 64.1 %San Juan County: 99.1 %Skagit County: 93.2 %Snohomish County: 62.4 %Spokane County: 70.7 %Stevens County: 61.1 %Thurston County: 79.5 %Walla Walla County: 81.9 %Whatcom County: 92 %Whitman County: 88.8 %Yakima County: 48.8 %
  • Under 64
  • 64 to 75
  • 75 to 82
  • 82 to 87
  • 87 to 92
  • 92 and over
  • No data
Share of days with good air quality (US EPA AQI), 2019, %. San Juan County is outlined. Same source and period for every area shown. Source: U.S. Environmental Protection Agency. Boundaries: U.S. Census Bureau cartographic boundary files.

Rankings

Definition

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.

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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 (Share of days with good air quality (US EPA AQI), San Juan County, 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, Share of days with good air quality (US EPA AQI), San Juan County, 2019. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/en/good-air-quality-days-share/san-juan-county-washington. 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. Share of days with good air quality (US EPA AQI), San Juan County, 2019. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/en/good-air-quality-days-share/san-juan-county-washington.

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, Share of days with good air quality (US EPA AQI), San Juan County, 2019 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/good-air-quality-days-share/san-juan-county-washington (Accessed: 12 October 2026).

BibTeX
@misc{environmental_share_of_days_with_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: Share of days with good air quality (US EPA AQI), San Juan County, 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/en/good-air-quality-days-share/san-juan-county-washington. 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: Share of days with good air quality (US EPA AQI), San Juan County, 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/en/good-air-quality-days-share/san-juan-county-washington
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/good-air-quality-days-share/san-juan-county-washington.
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

What is the share of days with good air quality (US EPA AQI) in San Juan County?

Share of days with good air quality (US EPA AQI) in San Juan County was 99.1% in 2019, according to EPA.

Where does this figure come from?

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 by Invokely on 2026-10-12.

Related statistics for San Juan County

All statistics for San Juan County | San Juan County in figures