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

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

Lincoln County had the highest share of days with good air quality (US EPA AQI) of 18 counties in 2019, at 99.7%. Albany County had the lowest, at 67.1%. The median was 87.4%. Source: EPA.

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Highest99.7Lincoln County
Lowest67.1Albany County
Median87.418 counties

Map of counties, 2019

Albany County: 67.1 %Big Horn County: 96.6 %Campbell County: 82.5 %Carbon County: 89.3 %Converse County: 86 %Fremont County: 79.7 %Johnson County: 94.8 %Laramie County: 81.1 %Lincoln County: 99.7 %Natrona County: 89.8 %Park County: 95.1 %Platte County: 93.3 %Sheridan County: 86.3 %Sublette County: 72.6 %Sweetwater County: 70.7 %Teton County: 88.5 %Uinta County: 86.3 %Weston County: 93.1 %
  • Under 80
  • 80 to 86
  • 86 to 89
  • 89 to 94
  • 94 and over
  • No data
%, 2019. 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, 2019

Lincoln County: 99.7 %Lincoln County99.7Big Horn County: 96.6 %Big Horn County96.6Park County: 95.1 %Park County95.1Johnson County: 94.8 %Johnson County94.8Platte County: 93.3 %Platte County93.3Weston County: 93.1 %Weston County93.1Natrona County: 89.8 %Natrona County89.8Carbon County: 89.3 %Carbon County89.3Teton County: 88.5 %Teton County88.5Sheridan County: 86.3 %Sheridan County86.3Uinta County: 86.3 %Uinta County86.3Converse County: 86 %Converse County86Campbell County: 82.5 %Campbell County82.5Laramie County: 81.1 %Laramie County81.1Fremont County: 79.7 %Fremont County79.7Sublette County: 72.6 %Sublette County72.6Sweetwater County: 70.7 %Sweetwater County70.7Albany County: 67.1 %Albany County67.1Lincoln County: 99.7 %Lincoln County99.7Big Horn County: 96.6 %Big Horn County96.6Park County: 95.1 %Park County95.1Johnson County: 94.8 %Johnson County94.8Platte County: 93.3 %Platte County93.3Weston County: 93.1 %Weston County93.1Natrona County: 89.8 %Natrona County89.8Carbon County: 89.3 %Carbon County89.3Teton County: 88.5 %Teton County88.5Sheridan County: 86.3 %Sheridan County86.3Uinta County: 86.3 %Uinta County86.3Converse County: 86 %Converse County86Campbell County: 82.5 %Campbell County82.5Laramie County: 81.1 %Laramie County81.1Fremont County: 79.7 %Fremont County79.7Sublette County: 72.6 %Sublette County72.6Sweetwater County: 70.7 %Sweetwater County70.7Albany County: 67.1 %Albany County67.1
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2019 (%)Change on 2018
1Lincoln County99.7+5.7 pts
2Big Horn County96.6+7.2 pts
3Park County95.1+3.6 pts
4Johnson County94.8+11.5 pts
5Platte County93.3-1.8 pts
6Weston County93.1+7.5 pts
7Natrona County89.8+11.4 pts
8Carbon County89.3+9.3 pts
9Teton County88.5+13.7 pts
10Sheridan County86.3+20.3 pts
10Uinta County86.3+7.7 pts
12Converse County86+1.1 pts
13Campbell County82.5+12.4 pts
14Laramie County81.1+2.2 pts
15Fremont County79.7+11.2 pts
16Sublette County72.6+9.6 pts
17Sweetwater County70.7+13.2 pts
18Albany County67.1+7.4 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. 3 counties with data in other periods have no value for 2019 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 Wyoming by share of days with good air quality (US EPA AQI), 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, Counties in Wyoming by share of days with good air quality (US EPA AQI), 2019. 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/wyoming-counties?period=2019. 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 Wyoming by share of days with good air quality (US EPA AQI), 2019. 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/wyoming-counties?period=2019.

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 Wyoming by share of days with good air quality (US EPA AQI), 2019 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/good-air-quality-days-share/wyoming-counties?period=2019 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_wyoming_by_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: Counties in Wyoming by share of days with good air quality (US EPA AQI), 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/rankings/good-air-quality-days-share/wyoming-counties?period=2019. 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 Wyoming by share of days with good air quality (US EPA AQI), 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/rankings/good-air-quality-days-share/wyoming-counties?period=2019
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/wyoming-counties?period=2019.
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

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

Lincoln County, with 99.7% in 2019, according to EPA.

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

Albany County, with 67.1% in 2019.

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. 3 counties have no value for 2019 and are not ranked.

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

Counties in Wyoming: more rankings