Median Air Quality Index (US EPA) in Ada County

Median Air Quality Index (US EPA) in Ada County was 42 in 2025, according to the U.S. Environmental Protection Agency. That is down 2 from 2024.

2025, index42
Change on 2024-2
Series high571980
Series low301995

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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Median Air Quality Index (US EPA) in Ada County, 1980 to 2025

3040506019801987199420012008201520251980: 57 index1981: 55 index1982: 53 index1983: 51 index1984: 39 index1985: 40 index1986: 44 index1987: 39 index1988: 34 index1989: 41 index1990: 45 index1991: 40 index1992: 40 index1993: 32 index1994: 33 index1995: 30 index1996: 30 index1997: 35 index1998: 35 index1999: 37 index2000: 33 index2001: 45 index2002: 45 index2003: 40 index2004: 44 index2005: 44 index2006: 48 index2007: 54 index2008: 49 index2009: 54 index2010: 55 index2011: 43 index2012: 41 index2013: 38 index2014: 41 index2015: 41 index2016: 41 index2017: 46 index2018: 42 index2019: 41 index2020: 44 index2021: 46 index2022: 48 index2023: 44 index2024: 44 index2025: 42 index3040506019801996201220251980: 57 index1981: 55 index1982: 53 index1983: 51 index1984: 39 index1985: 40 index1986: 44 index1987: 39 index1988: 34 index1989: 41 index1990: 45 index1991: 40 index1992: 40 index1993: 32 index1994: 33 index1995: 30 index1996: 30 index1997: 35 index1998: 35 index1999: 37 index2000: 33 index2001: 45 index2002: 45 index2003: 40 index2004: 44 index2005: 44 index2006: 48 index2007: 54 index2008: 49 index2009: 54 index2010: 55 index2011: 43 index2012: 41 index2013: 38 index2014: 41 index2015: 41 index2016: 41 index2017: 46 index2018: 42 index2019: 41 index2020: 44 index2021: 46 index2022: 48 index2023: 44 index2024: 44 index2025: 42 index
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 46 values
Periodindex
202542
202444
202344
202248
202146
202044
201941
201842
201746
201641
201541
201441
201338
201241
201143
201055
200954
200849
200754
200648
200544
200444
200340
200245
200145
200033
199937
199835
199735
199630
199530
199433
199332
199240
199140
199045
198941
198834
198739
198644
198540
198439
198351
198253
198155
198057

Ada County compared with nearby places

Ada County: 42 indexBannock County: 36 indexBenewah County: 41 indexBlaine County: 17 indexBoise County: 42 indexBonner County: 47 indexBonneville County: 22 indexButte County: 42 indexCanyon County: 36 indexCuster County: 10 indexFranklin County: 21 indexIdaho County: 40 indexKootenai County: 31 indexLatah County: 31 indexLemhi County: 29 indexNez Perce County: 33 indexShoshone County: 44 indexTwin Falls County: 26 indexValley County: 34 index
  • Under 24
  • 24 to 31
  • 31 to 36
  • 36 to 42
  • 42 and over
  • No data
Median Air Quality Index (US EPA), 2025, index. Ada 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.

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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), Ada County, 1980 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), Ada County, 1980 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/ada-county-idaho. 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), Ada County, 1980 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/ada-county-idaho.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Median Air Quality Index (US EPA), Ada County, 1980 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/ada-county-idaho (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), Ada County, 1980 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/ada-county-idaho. 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), Ada County, 1980 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/ada-county-idaho
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/median-air-quality-index/ada-county-idaho.
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  - 
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Questions

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

Median Air Quality Index (US EPA) in Ada County was 42 in 2025, according to the U.S. Environmental Protection Agency. That is down 2 from 2024.

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 Ada County?

57 in 1980, the highest value since 1980 in this series.

Related statistics for Ada County

All statistics for Ada County | Ada County in figures