Data / Highest daily Air Quality Index (US EPA) / Johnson County

Highest daily Air Quality Index (US EPA) in Johnson County

Highest daily Air Quality Index (US EPA) in Johnson County was 84 in 2025, according to the U.S. Environmental Protection Agency. That is down 28 from 2024.

2025, index84
Change on 2024-28
Series high1262021
Series low332009

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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Highest daily Air Quality Index (US EPA) in Johnson County, 2002 to 2025

204060801001201402002200620102014202020252002: 55 index2003: 62 index2004: 52 index2005: 52 index2006: 65 index2007: 75 index2008: 54 index2009: 33 index2010: 39 index2011: 55 index2012: 66 index2013: 73 index2014: 68 index2015: 61 index2018: 90 index2019: 80 index2020: 93 index2021: 126 index2022: 101 index2023: 64 index2024: 112 index2025: 84 index2550751001251502002201020252002: 55 index2003: 62 index2004: 52 index2005: 52 index2006: 65 index2007: 75 index2008: 54 index2009: 33 index2010: 39 index2011: 55 index2012: 66 index2013: 73 index2014: 68 index2015: 61 index2018: 90 index2019: 80 index2020: 93 index2021: 126 index2022: 101 index2023: 64 index2024: 112 index2025: 84 index
index. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 22 values
Periodindex
202584
2024112
202364
2022101
2021126
202093
201980
201890
201561
201468
201373
201266
201155
201039
200933
200854
200775
200665
200552
200452
200362
200255

Johnson County compared with nearby places

Albany County: 172 indexCampbell County: 156 indexCarbon County: 43 indexConverse County: 63 indexFremont County: 100 indexJohnson County: 84 indexLaramie County: 108 indexLincoln County: 77 indexNatrona County: 76 indexPark County: 73 indexPlatte County: 723 indexSheridan County: 75 indexSublette County: 164 indexSweetwater County: 118 indexTeton County: 90 indexUinta County: 50 indexWashakie County: 68 index
  • Under 69
  • 69 to 76
  • 76 to 96
  • 96 to 150
  • 150 and over
  • No data
Highest daily Air Quality Index (US EPA), 2025, index. Johnson 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

Highest daily Air Quality Index (AQI) value recorded in a US county during the year, from the EPA AirData annual summaries. Values above 500 are beyond the AQI scale and are published as EPA computes them.

A single day decides the value, so one wildfire or dust event can set it. Dust from the dry Owens Lake bed puts Inyo and Mono counties in California in the thousands. 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: highest 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: highest daily AQI (Highest daily Air Quality Index (US EPA), Johnson County, 2002 to 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: highest daily AQI, Highest daily Air Quality Index (US EPA), Johnson County, 2002 to 2025. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/en/highest-daily-air-quality-index/johnson-county-wyoming. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: highest daily AQI. Highest daily Air Quality Index (US EPA), Johnson County, 2002 to 2025. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/en/highest-daily-air-quality-index/johnson-county-wyoming.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: highest daily AQI, Highest daily Air Quality Index (US EPA), Johnson County, 2002 to 2025 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/highest-daily-air-quality-index/johnson-county-wyoming (Accessed: 12 October 2026).

BibTeX
@misc{environmental_highest_daily_air_quality_2025,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: highest daily AQI: Highest daily Air Quality Index (US EPA), Johnson County, 2002 to 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/en/highest-daily-air-quality-index/johnson-county-wyoming. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: highest 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: highest daily AQI: Highest daily Air Quality Index (US EPA), Johnson County, 2002 to 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/en/highest-daily-air-quality-index/johnson-county-wyoming
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/highest-daily-air-quality-index/johnson-county-wyoming.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: highest daily AQI. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
ER  -
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Questions

What is the highest daily Air Quality Index (US EPA) in Johnson County?

Highest daily Air Quality Index (US EPA) in Johnson County was 84 in 2025, according to the U.S. Environmental Protection Agency. That is down 28 from 2024.

Where does this figure come from?

U.S. Environmental Protection Agency. EPA AirData annual AQI by county: highest daily AQI. Retrieved by Invokely on 2026-10-12.

What was the highest highest daily Air Quality Index (US EPA) in Johnson County?

126 in 2021, the highest value since 2002 in this series.

Related statistics for Johnson County

All statistics for Johnson County | Johnson County in figures