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

Median Air Quality Index (US EPA) in Warren County

Median Air Quality Index (US EPA) in Warren County was 44 in 2025, according to the U.S. Environmental Protection Agency. That is up 1 from 2024.

2025, index44
Change on 2024+1
Series high602013
Series low201980

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 Warren County, 1980 to 2025

203040506019801987199420012008201520251980: 20 index1981: 32 index1982: 35 index1983: 41 index1984: 34 index1985: 39 index1986: 43 index1987: 48 index1988: 50 index1989: 50 index1990: 47 index1991: 58 index1992: 44 index1993: 49 index1994: 47 index1995: 49 index1996: 46 index1997: 45 index1998: 54 index1999: 54 index2000: 45 index2001: 45 index2002: 48 index2003: 46 index2004: 46 index2005: 50 index2006: 48 index2007: 57 index2008: 52 index2009: 50 index2010: 59 index2011: 57 index2012: 58 index2013: 60 index2014: 57 index2015: 47 index2016: 50 index2017: 49 index2018: 48 index2019: 47 index2020: 44 index2021: 44 index2022: 44 index2023: 44 index2024: 43 index2025: 44 index203040506019801996201220251980: 20 index1981: 32 index1982: 35 index1983: 41 index1984: 34 index1985: 39 index1986: 43 index1987: 48 index1988: 50 index1989: 50 index1990: 47 index1991: 58 index1992: 44 index1993: 49 index1994: 47 index1995: 49 index1996: 46 index1997: 45 index1998: 54 index1999: 54 index2000: 45 index2001: 45 index2002: 48 index2003: 46 index2004: 46 index2005: 50 index2006: 48 index2007: 57 index2008: 52 index2009: 50 index2010: 59 index2011: 57 index2012: 58 index2013: 60 index2014: 57 index2015: 47 index2016: 50 index2017: 49 index2018: 48 index2019: 47 index2020: 44 index2021: 44 index2022: 44 index2023: 44 index2024: 43 index2025: 44 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
202544
202443
202344
202244
202144
202044
201947
201848
201749
201650
201547
201457
201360
201258
201157
201059
200950
200852
200757
200648
200550
200446
200346
200248
200145
200045
199954
199854
199745
199646
199549
199447
199349
199244
199158
199047
198950
198850
198748
198643
198539
198434
198341
198235
198132
198020

Warren County compared with nearby places

Allen County: 42 indexAshtabula County: 43 indexAthens County: 31 indexBelmont County: 42 indexButler County: 55 indexClark County: 45 indexClermont County: 41 indexClinton County: 41 indexColumbiana County: 12 indexCuyahoga County: 53 indexDelaware County: 40 indexFranklin County: 53 indexGeauga County: 42 indexGreene County: 40 indexHamilton County: 54 indexJefferson County: 49 indexKnox County: 39 indexLake County: 42 indexLawrence County: 42 indexLicking County: 40 indexLorain County: 39 indexLucas County: 52 indexMadison County: 43 indexMahoning County: 44 indexMedina County: 43 indexMiami County: 40 indexMontgomery County: 46 indexNoble County: 37 indexPortage County: 43 indexPreble County: 43 indexScioto County: 46 indexStark County: 49 indexSummit County: 44 indexTrumbull County: 46 indexWarren County: 44 indexWashington County: 40 indexWood County: 39 index
  • Under 40
  • 40 to 41
  • 41 to 43
  • 43 to 44
  • 44 to 49
  • 49 and over
  • No data
Median Air Quality Index (US EPA), 2025, index. Warren 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), Warren 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), Warren 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/warren-county-ohio. 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), Warren 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/warren-county-ohio.

Harvard

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

Median Air Quality Index (US EPA) in Warren County was 44 in 2025, according to the U.S. Environmental Protection Agency. That is up 1 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 Warren County?

60 in 2013, the highest value since 1980 in this series.

Related statistics for Warren County

All statistics for Warren County | Warren County in figures