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

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

Garfield County had the highest share of days with good air quality (US EPA AQI) of 17 counties in 2024, at 97.5%. Salt Lake County had the lowest, at 41%. The median was 65%. Source: EPA.

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Highest97.5Garfield County
Lowest41Salt Lake County
Median6517 counties

Map of counties, 2024

Box Elder County: 58.5 %Cache County: 65 %Carbon County: 76 %Davis County: 63.9 %Duchesne County: 61.5 %Garfield County: 97.5 %Grand County: 62.7 %Iron County: 83 %Salt Lake County: 41 %San Juan County: 77.5 %Tooele County: 62 %Uintah County: 59.6 %Utah County: 57.4 %Wasatch County: 90.2 %Washington County: 76 %Wayne County: 97.5 %Weber County: 66.4 %
  • Under 60
  • 60 to 63
  • 63 to 72
  • 72 to 82
  • 82 and over
  • No data
%, 2024. 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, 2024

Garfield County: 97.5 %Garfield County97.5Wayne County: 97.5 %Wayne County97.5Wasatch County: 90.2 %Wasatch County90.2Iron County: 83 %Iron County83San Juan County: 77.5 %San Juan County77.5Carbon County: 76 %Carbon County76Washington County: 76 %Washington County76Weber County: 66.4 %Weber County66.4Cache County: 65 %Cache County65Davis County: 63.9 %Davis County63.9Grand County: 62.7 %Grand County62.7Tooele County: 62 %Tooele County62Duchesne County: 61.5 %Duchesne County61.5Uintah County: 59.6 %Uintah County59.6Box Elder County: 58.5 %Box Elder County58.5Utah County: 57.4 %Utah County57.4Salt Lake County: 41 %Salt Lake County41Garfield County: 97.5 %Garfield County97.5Wayne County: 97.5 %Wayne County97.5Wasatch County: 90.2 %Wasatch County90.2Iron County: 83 %Iron County83San Juan County: 77.5 %San Juan County77.5Carbon County: 76 %Carbon County76Washington County: 76 %Washington County76Weber County: 66.4 %Weber County66.4Cache County: 65 %Cache County65Davis County: 63.9 %Davis County63.9Grand County: 62.7 %Grand County62.7Tooele County: 62 %Tooele County62Duchesne County: 61.5 %Duchesne County61.5Uintah County: 59.6 %Uintah County59.6Box Elder County: 58.5 %Box Elder County58.5Utah County: 57.4 %Utah County57.4Salt Lake County: 41 %Salt Lake County41
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2024 (%)Change on 2023
1Garfield County97.5-2.5 pts
1Wayne County97.5-0.8 pts
3Wasatch County90.2n/a
4Iron County83-1.7 pts
5San Juan County77.5+2.7 pts
6Carbon County76-14.6 pts
6Washington County76-3.7 pts
8Weber County66.4+6.7 pts
9Cache County65+5 pts
10Davis County63.9+6.1 pts
11Grand County62.7+7.5 pts
12Tooele County62-5.9 pts
13Duchesne County61.5+12.2 pts
14Uintah County59.6+17.4 pts
15Box Elder County58.5-25.4 pts
16Utah County57.4+2.3 pts
17Salt Lake County41+0.2 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 2024 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 Utah by share of days with good air quality (US EPA AQI), 2024) [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 Utah by share of days with good air quality (US EPA AQI), 2024. 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/utah-counties?period=2024. 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 Utah by share of days with good air quality (US EPA AQI), 2024. 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/utah-counties?period=2024.

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 Utah by share of days with good air quality (US EPA AQI), 2024 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/good-air-quality-days-share/utah-counties?period=2024 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_utah_by_2024,
  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 Utah by share of days with good air quality (US EPA AQI), 2024}},
  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/utah-counties?period=2024. 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 Utah by share of days with good air quality (US EPA AQI), 2024
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/utah-counties?period=2024
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/utah-counties?period=2024.
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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Rank Counties in Utah by share of days with good air quality (US EPA AQI) using official data, and cite the source.
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Questions

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

Garfield County, with 97.5% in 2024, according to EPA.

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

Salt Lake County, with 41% in 2024.

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 2024 and are not ranked.

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

Counties in Utah: more rankings