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

Median Air Quality Index (US EPA) in Waukesha County

Median Air Quality Index (US EPA) in Waukesha County was 41 in 2025, according to the U.S. Environmental Protection Agency. That is down 2 from 2024.

2025, index41
Change on 2024-2
Series high572000
Series low211980

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 Waukesha County, 1980 to 2025

203040506019801987199420012008201520251980: 21 index1981: 28 index1982: 32 index1983: 31 index1984: 31 index1985: 28 index1986: 31 index1987: 34 index1988: 31 index1989: 39 index1990: 34 index1991: 28 index1992: 26 index1993: 28 index1994: 27 index1995: 26 index1996: 24 index1997: 24 index1998: 31 index1999: 37 index2000: 57 index2001: 56 index2002: 53 index2003: 50 index2004: 39 index2005: 43 index2006: 36 index2007: 36 index2008: 36 index2009: 34 index2010: 41 index2011: 44 index2012: 56 index2013: 47 index2014: 49 index2015: 44 index2016: 44 index2017: 43 index2018: 46 index2019: 45 index2020: 44 index2021: 51 index2022: 47 index2023: 52 index2024: 43 index2025: 41 index203040506019801996201220251980: 21 index1981: 28 index1982: 32 index1983: 31 index1984: 31 index1985: 28 index1986: 31 index1987: 34 index1988: 31 index1989: 39 index1990: 34 index1991: 28 index1992: 26 index1993: 28 index1994: 27 index1995: 26 index1996: 24 index1997: 24 index1998: 31 index1999: 37 index2000: 57 index2001: 56 index2002: 53 index2003: 50 index2004: 39 index2005: 43 index2006: 36 index2007: 36 index2008: 36 index2009: 34 index2010: 41 index2011: 44 index2012: 56 index2013: 47 index2014: 49 index2015: 44 index2016: 44 index2017: 43 index2018: 46 index2019: 45 index2020: 44 index2021: 51 index2022: 47 index2023: 52 index2024: 43 index2025: 41 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
202541
202443
202352
202247
202151
202044
201945
201846
201743
201644
201544
201449
201347
201256
201144
201041
200934
200836
200736
200636
200543
200439
200350
200253
200156
200057
199937
199831
199724
199624
199526
199427
199328
199226
199128
199034
198939
198831
198734
198631
198528
198431
198331
198232
198128
198021

Waukesha County compared with nearby places

Ashland County: 36 indexBrown County: 37 indexColumbia County: 40 indexDane County: 41 indexDodge County: 40 indexDoor County: 38 indexEau Claire County: 38 indexFond du Lac County: 37 indexForest County: 39 indexGrant County: 37 indexJackson County: 36 indexJefferson County: 40 indexKenosha County: 42 indexKewaunee County: 39 indexLa Crosse County: 37 indexManitowoc County: 36 indexMarathon County: 36 indexMilwaukee County: 43 indexMonroe County: 36 indexOutagamie County: 38 indexOzaukee County: 36 indexRacine County: 41 indexRock County: 42 indexSauk County: 35 indexSheboygan County: 41 indexTaylor County: 34 indexVilas County: 36 indexWalworth County: 42 indexWaukesha County: 41 index
  • Under 36
  • 36 to 37
  • 37 to 39
  • 39 to 41
  • 41 and over
  • No data
Median Air Quality Index (US EPA), 2025, index. Waukesha 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), Waukesha 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), Waukesha 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/waukesha-county-wisconsin. 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), Waukesha 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/waukesha-county-wisconsin.

Harvard

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

Median Air Quality Index (US EPA) in Waukesha County was 41 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 Waukesha County?

57 in 2000, the highest value since 1980 in this series.

Related statistics for Waukesha County

All statistics for Waukesha County | Waukesha County in figures