Data / Median Air Quality Index (US EPA) / Lincoln County

Median Air Quality Index (US EPA) in Lincoln County

Median Air Quality Index (US EPA) in Lincoln County was 45 in 2025, according to the U.S. Environmental Protection Agency. That is down 4 from 2024. That is the 1st highest of 23 counties in 2025.

2025, index45
Change on 2024-4
Rank1st of 23Counties in Montana ranked
Series high671987
Series low221995

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

Get an email when a new figure is out or this one is revised.
Keep it in a collection in your library.

Median Air Quality Index (US EPA) in Lincoln County, 1985 to 2025

20304050607019851991199720032009201520251985: 53 index1986: 63 index1987: 67 index1988: 51 index1989: 47 index1990: 45 index1991: 41 index1992: 42 index1993: 44 index1994: 30 index1995: 22 index1996: 24 index1997: 25 index1998: 24 index1999: 26 index2000: 26 index2001: 27 index2002: 27 index2003: 23 index2004: 30 index2005: 31 index2006: 56 index2007: 54 index2008: 53 index2009: 52 index2010: 52 index2011: 36 index2012: 51 index2013: 47 index2014: 41 index2015: 52 index2016: 44 index2017: 53 index2018: 55 index2019: 48 index2020: 52 index2021: 56 index2022: 49 index2023: 53 index2024: 49 index2025: 45 index2040608019851999201320251985: 53 index1986: 63 index1987: 67 index1988: 51 index1989: 47 index1990: 45 index1991: 41 index1992: 42 index1993: 44 index1994: 30 index1995: 22 index1996: 24 index1997: 25 index1998: 24 index1999: 26 index2000: 26 index2001: 27 index2002: 27 index2003: 23 index2004: 30 index2005: 31 index2006: 56 index2007: 54 index2008: 53 index2009: 52 index2010: 52 index2011: 36 index2012: 51 index2013: 47 index2014: 41 index2015: 52 index2016: 44 index2017: 53 index2018: 55 index2019: 48 index2020: 52 index2021: 56 index2022: 49 index2023: 53 index2024: 49 index2025: 45 index
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 41 values
Periodindex
202545
202449
202353
202249
202156
202052
201948
201855
201753
201644
201552
201441
201347
201251
201136
201052
200952
200853
200754
200656
200531
200430
200323
200227
200127
200026
199926
199824
199725
199624
199522
199430
199344
199242
199141
199045
198947
198851
198767
198663
198553

Lincoln County compared with nearby places

Beaverhead County: 13 indexCuster County: 40 indexDawson County: 18 indexFergus County: 41 indexFlathead County: 41 indexGallatin County: 11 indexGlacier County: 23 indexHill County: 14 indexLake County: 11 indexLewis and Clark County: 44 indexLincoln County: 45 indexMissoula County: 38 indexPhillips County: 19 indexPowell County: 13 indexRavalli County: 21 indexRichland County: 40 indexRoosevelt County: 16 indexRosebud County: 11 indexSanders County: 16 indexSheridan County: 18 indexSilver Bow County: 28 indexTeton County: 12 indexYellowstone County: 38 index
  • Under 13
  • 13 to 18
  • 18 to 24
  • 24 to 40
  • 40 and over
  • No data
Median Air Quality Index (US EPA), 2025, index. Lincoln 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

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.

Report a problem with this figure

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 (Median Air Quality Index (US EPA), Lincoln County, 1985 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: median daily AQI, Median Air Quality Index (US EPA), Lincoln County, 1985 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/median-air-quality-index/lincoln-county-montana. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Median Air Quality Index (US EPA), Lincoln County, 1985 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/median-air-quality-index/lincoln-county-montana.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Median Air Quality Index (US EPA), Lincoln County, 1985 to 2025 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/median-air-quality-index/lincoln-county-montana (Accessed: 12 October 2026).

BibTeX
@misc{environmental_median_air_quality_index_2025,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Median Air Quality Index (US EPA), Lincoln County, 1985 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/median-air-quality-index/lincoln-county-montana. 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: Median Air Quality Index (US EPA), Lincoln County, 1985 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/median-air-quality-index/lincoln-county-montana
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/median-air-quality-index/lincoln-county-montana.
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:

What is the latest median Air Quality Index (US EPA) in Lincoln County? Cite the source.
get_value {"indicator":"aqi_median","place":"us-county-30053"}
GET https://invokely.ai/api/v1/value?indicator=aqi_median&place=us-county-30053

Connect Claude, ChatGPT or Cursor in one step. The trial answers 25 calls a day without an account.

Questions

What is the median Air Quality Index (US EPA) in Lincoln County?

Median Air Quality Index (US EPA) in Lincoln County was 45 in 2025, according to the U.S. Environmental Protection Agency. That is down 4 from 2024. That is the 1st highest of 23 counties in 2025.

Where does this figure come from?

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

What was the highest median Air Quality Index (US EPA) in Lincoln County?

67 in 1987, the highest value since 1985 in this series.

Related statistics for Lincoln County

All statistics for Lincoln County | Lincoln County in figures