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

Median Air Quality Index (US EPA) in Washington County

Median Air Quality Index (US EPA) in Washington County was 34 in 2025, according to the U.S. Environmental Protection Agency. That is down 1 from 2024. That is the 15th highest of 23 counties in 2025.

2025, index34
Change on 2024-1
Rank15th of 23Counties in Minnesota ranked
Series high532018
Series low261997

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 Washington County, 1980 to 2025

203040506019801987199420012008201520251980: 44 index1981: 31 index1982: 31 index1983: 41 index1984: 37 index1985: 39 index1986: 37 index1987: 37 index1988: 46 index1989: 42 index1990: 39 index1991: 36 index1992: 34 index1993: 32 index1994: 35 index1995: 38 index1996: 38 index1997: 26 index1998: 36 index1999: 35 index2000: 39 index2001: 40 index2002: 40 index2003: 43 index2004: 36 index2005: 40 index2006: 40 index2007: 40 index2008: 42 index2009: 41 index2010: 40 index2011: 37 index2012: 49 index2013: 47 index2014: 44 index2015: 46 index2016: 36 index2017: 46 index2018: 53 index2019: 37 index2020: 33 index2021: 35 index2022: 36 index2023: 42 index2024: 35 index2025: 34 index203040506019801996201220251980: 44 index1981: 31 index1982: 31 index1983: 41 index1984: 37 index1985: 39 index1986: 37 index1987: 37 index1988: 46 index1989: 42 index1990: 39 index1991: 36 index1992: 34 index1993: 32 index1994: 35 index1995: 38 index1996: 38 index1997: 26 index1998: 36 index1999: 35 index2000: 39 index2001: 40 index2002: 40 index2003: 43 index2004: 36 index2005: 40 index2006: 40 index2007: 40 index2008: 42 index2009: 41 index2010: 40 index2011: 37 index2012: 49 index2013: 47 index2014: 44 index2015: 46 index2016: 36 index2017: 46 index2018: 53 index2019: 37 index2020: 33 index2021: 35 index2022: 36 index2023: 42 index2024: 35 index2025: 34 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
202534
202435
202342
202236
202135
202033
201937
201853
201746
201636
201546
201444
201347
201249
201137
201040
200941
200842
200740
200640
200540
200436
200343
200240
200140
200039
199935
199836
199726
199638
199538
199435
199332
199234
199136
199039
198942
198846
198737
198637
198539
198437
198341
198231
198131
198044

Washington County compared with nearby places

Anoka County: 38 indexBecker County: 38 indexBeltrami County: 36 indexBlue Earth County: 42 indexCarlton County: 33 indexCass County: 28 indexCook County: 16 indexCrow Wing County: 37 indexDakota County: 35 indexGoodhue County: 38 indexHennepin County: 45 indexLake County: 31 indexLyon County: 37 indexMille Lacs County: 34 indexOlmsted County: 39 indexPine County: 23 indexRamsey County: 34 indexSt. Louis County: 42 indexScott County: 38 indexStearns County: 37 indexWashington County: 34 indexWinona County: 21 indexWright County: 39 index
  • Under 32
  • 32 to 35
  • 35 to 37
  • 37 to 39
  • 39 and over
  • No data
Median Air Quality Index (US EPA), 2025, index. Washington 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), Washington 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), Washington 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/washington-county-minnesota. 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), Washington 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/washington-county-minnesota.

Harvard

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

Median Air Quality Index (US EPA) in Washington County was 34 in 2025, according to the U.S. Environmental Protection Agency. That is down 1 from 2024. That is the 15th 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 Washington County?

53 in 2018, the highest value since 1980 in this series.

Related statistics for Washington County

All statistics for Washington County | Washington County in figures