Data / Rankings / Median Air Quality Index (US EPA) / Counties in Utah

Counties in Utah by median Air Quality Index (US EPA), 2025

Salt Lake County had the highest median Air Quality Index (US EPA) of 17 counties in 2025, at 57. Garfield County had the lowest, at 12. The median was 45. Source: the U.S. Environmental Protection Agency.

Keep it in a collection in your library.
Highest57Salt Lake County
Lowest12Garfield County
Median4517 counties

Map of counties, 2025

Box Elder County: 45 indexCache County: 44 indexCarbon County: 44 indexDavis County: 46 indexDuchesne County: 46 indexGarfield County: 12 indexGrand County: 47 indexIron County: 44 indexSalt Lake County: 57 indexSan Juan County: 44 indexTooele County: 44 indexUintah County: 48 indexUtah County: 48 indexWasatch County: 45 indexWashington County: 44 indexWayne County: 14 indexWeber County: 45 index
  • Under 44
  • 44 to 45
  • 45 to 47
  • 47 and over
  • No data
index, 2025. Hatched areas have no value for this period. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2025

Salt Lake County: 57 indexSalt Lake County57Uintah County: 48 indexUintah County48Utah County: 48 indexUtah County48Grand County: 47 indexGrand County47Davis County: 46 indexDavis County46Duchesne County: 46 indexDuchesne County46Box Elder County: 45 indexBox Elder County45Wasatch County: 45 indexWasatch County45Weber County: 45 indexWeber County45Cache County: 44 indexCache County44Carbon County: 44 indexCarbon County44Iron County: 44 indexIron County44San Juan County: 44 indexSan Juan County44Tooele County: 44 indexTooele County44Washington County: 44 indexWashington County44Wayne County: 14 indexWayne County14Garfield County: 12 indexGarfield County12Salt Lake County: 57 indexSalt Lake County57Uintah County: 48 indexUintah County48Utah County: 48 indexUtah County48Grand County: 47 indexGrand County47Davis County: 46 indexDavis County46Duchesne County: 46 indexDuchesne County46Box Elder County: 45 indexBox Elder County45Wasatch County: 45 indexWasatch County45Weber County: 45 indexWeber County45Cache County: 44 indexCache County44Carbon County: 44 indexCarbon County44Iron County: 44 indexIron County44San Juan County: 44 indexSan Juan County44Tooele County: 44 indexTooele County44Washington County: 44 indexWashington County44Wayne County: 14 indexWayne County14Garfield County: 12 indexGarfield County12
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2025
index		Change on 2024
1Salt Lake County57+3
2Uintah County480
2Utah County48+1
4Grand County47-1
5Davis County460
5Duchesne County46-1
7Box Elder County45-2
7Wasatch County45+8
7Weber County450
10Cache County440
10Carbon County440
10Iron County44+1
10San Juan County440
10Tooele County44-2
10Washington County440
16Wayne County14+3
17Garfield County12+3

Other periods

About this ranking

Median of the daily Air Quality Index (AQI) values of a US county over the days of the year with an AQI, from the EPA AirData annual summaries.

More on how it is measured
  • The daily county AQI is the highest AQI among the monitors and pollutants reported that day (ozone, PM2.5, PM10, carbon monoxide and nitrogen dioxide).
  • Lower is cleaner: 0 to 50 is good, 51 to 100 moderate and above 100 unhealthy for sensitive groups.

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 2025 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: median daily AQI. 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: median daily AQI (Counties in Utah by median Air Quality Index (US EPA), 2025) [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: median daily AQI, Counties in Utah by median Air Quality Index (US EPA), 2025. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/median-air-quality-index/utah-counties. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Counties in Utah by median Air Quality Index (US EPA), 2025. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/median-air-quality-index/utah-counties.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Counties in Utah by median Air Quality Index (US EPA), 2025 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/median-air-quality-index/utah-counties (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_utah_by_2025,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Counties in Utah by median Air Quality Index (US EPA), 2025}},
  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/median-air-quality-index/utah-counties. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. 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: median daily AQI: Counties in Utah by median Air Quality Index (US EPA), 2025
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/median-air-quality-index/utah-counties
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/utah-counties.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. 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 Utah by median Air Quality Index (US EPA) using official data, and cite the source.
rank_places {"indicator":"aqi_median","level":"province","within":"Utah","limit":10}
GET https://invokely.ai/api/v1/rank?indicator=aqi_median&level=province&within=Utah&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 median Air Quality Index (US EPA)?

Salt Lake County, with 57 in 2025, according to the U.S. Environmental Protection Agency.

Which county has the lowest median Air Quality Index (US EPA)?

Garfield County, with 12 in 2025.

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: median daily AQI. Retrieved 2026-10-12. 2 counties have no value for 2025 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Utah: more rankings