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

Median Air Quality Index (US EPA) in Adams County

Median Air Quality Index (US EPA) in Adams County was 49 in 2025, according to the U.S. Environmental Protection Agency. That is down 6 from 2024. That is the 4th highest of 30 counties in 2025.

2025, index49
Change on 2024-6
Rank4th of 30Counties in Colorado ranked
Series high641986
Series low391990

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 Adams County, 1980 to 2025

3540455055606519801987199420012008201520251980: 58 index1981: 54 index1982: 44 index1983: 56 index1984: 50 index1985: 54 index1986: 64 index1987: 54 index1988: 49 index1989: 49 index1990: 39 index1991: 48 index1992: 51 index1993: 50 index1994: 55 index1995: 46 index1996: 49 index1997: 47 index1998: 51 index1999: 52 index2000: 50 index2001: 54 index2002: 50 index2003: 49 index2004: 49 index2005: 50 index2006: 50 index2007: 53 index2008: 49 index2009: 47 index2010: 44 index2011: 50 index2012: 49 index2013: 48 index2014: 48 index2015: 45 index2016: 46 index2017: 52 index2018: 54 index2019: 50 index2020: 49 index2021: 49 index2022: 51 index2023: 51 index2024: 55 index2025: 49 index304050607019801996201220251980: 58 index1981: 54 index1982: 44 index1983: 56 index1984: 50 index1985: 54 index1986: 64 index1987: 54 index1988: 49 index1989: 49 index1990: 39 index1991: 48 index1992: 51 index1993: 50 index1994: 55 index1995: 46 index1996: 49 index1997: 47 index1998: 51 index1999: 52 index2000: 50 index2001: 54 index2002: 50 index2003: 49 index2004: 49 index2005: 50 index2006: 50 index2007: 53 index2008: 49 index2009: 47 index2010: 44 index2011: 50 index2012: 49 index2013: 48 index2014: 48 index2015: 45 index2016: 46 index2017: 52 index2018: 54 index2019: 50 index2020: 49 index2021: 49 index2022: 51 index2023: 51 index2024: 55 index2025: 49 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
202549
202455
202351
202251
202149
202049
201950
201854
201752
201646
201545
201448
201348
201249
201150
201044
200947
200849
200753
200650
200550
200449
200349
200250
200154
200050
199952
199851
199747
199649
199546
199455
199350
199251
199148
199039
198949
198849
198754
198664
198554
198450
198356
198244
198154
198058

Adams County compared with nearby places

Adams County: 49 indexAlamosa County: 25 indexArapahoe County: 48 indexArchuleta County: 34 indexBoulder County: 48 indexChaffee County: 48 indexClear Creek County: 48 indexDelta County: 29 indexDenver County: 50 indexDouglas County: 46 indexEl Paso County: 46 indexFremont County: 23 indexGarfield County: 47 indexGilpin County: 46 indexGrand County: 44 indexGunnison County: 46 indexJackson County: 9 indexJefferson County: 48 indexLa Plata County: 48 indexLarimer County: 50 indexMesa County: 46 indexMontezuma County: 45 indexPark County: 48 indexPitkin County: 19 indexProwers County: 27 indexPueblo County: 45 indexRoutt County: 22 indexSan Juan County: 12 indexSan Miguel County: 36 indexWeld County: 52 index
  • Under 25
  • 25 to 41
  • 41 to 46
  • 46 to 48
  • 48 and over
  • No data
Median Air Quality Index (US EPA), 2025, index. Adams 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), Adams 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), Adams 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/adams-county-colorado. 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), Adams 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/adams-county-colorado.

Harvard

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

Median Air Quality Index (US EPA) in Adams County was 49 in 2025, according to the U.S. Environmental Protection Agency. That is down 6 from 2024. That is the 4th highest of 30 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 Adams County?

64 in 1986, the highest value since 1980 in this series.

Related statistics for Adams County

All statistics for Adams County | Adams County in figures