Median Air Quality Index (US EPA) in Monroe County

Median Air Quality Index (US EPA) in Monroe County was 35 in 2025, according to the U.S. Environmental Protection Agency. That is unchanged from 2024. That is the 19th highest of 21 counties in 2025.

2025, index35
Change on 20240
Series high512001
Series low281987

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 Monroe County, 1987 to 2025

2530354045505519871993199920052011201720251987: 28 index1988: 40 index1989: 35 index1990: 32 index1991: 36 index1992: 37 index1993: 39 index1994: 44 index1995: 46 index1996: 45 index1997: 46 index1998: 46 index1999: 50 index2000: 48 index2001: 51 index2002: 50 index2003: 48 index2004: 43 index2005: 50 index2006: 46 index2007: 44 index2008: 40 index2009: 37 index2010: 41 index2011: 40 index2012: 32 index2013: 35 index2014: 34 index2015: 31 index2016: 32 index2017: 37 index2018: 35 index2019: 35 index2020: 31 index2021: 32 index2022: 34 index2023: 38 index2024: 35 index2025: 35 index203040506019872000201320251987: 28 index1988: 40 index1989: 35 index1990: 32 index1991: 36 index1992: 37 index1993: 39 index1994: 44 index1995: 46 index1996: 45 index1997: 46 index1998: 46 index1999: 50 index2000: 48 index2001: 51 index2002: 50 index2003: 48 index2004: 43 index2005: 50 index2006: 46 index2007: 44 index2008: 40 index2009: 37 index2010: 41 index2011: 40 index2012: 32 index2013: 35 index2014: 34 index2015: 31 index2016: 32 index2017: 37 index2018: 35 index2019: 35 index2020: 31 index2021: 32 index2022: 34 index2023: 38 index2024: 35 index2025: 35 index
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 39 values
Periodindex
202535
202435
202338
202234
202132
202031
201935
201835
201737
201632
201531
201434
201335
201232
201140
201041
200937
200840
200744
200646
200550
200443
200348
200250
200151
200048
199950
199846
199746
199645
199546
199444
199339
199237
199136
199032
198935
198840
198728

Monroe County compared with nearby places

Andrew County: 40 indexBoone County: 37 indexBuchanan County: 46 indexCallaway County: 41 indexCass County: 41 indexCedar County: 39 indexClay County: 42 indexClinton County: 41 indexGreene County: 45 indexJackson County: 47 indexJasper County: 38 indexJefferson County: 42 indexLincoln County: 41 indexMonroe County: 35 indexPerry County: 41 indexSt. Charles County: 40 indexSte. Genevieve County: 41 indexSt. Louis County: 43 indexStoddard County: 21 indexTaney County: 28 indexSt. Louis city: 55 index
  • Under 38
  • 38 to 41
  • 41 to 43
  • 43 and over
  • No data
Median Air Quality Index (US EPA), 2025, index. Monroe 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), Monroe County, 1987 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), Monroe County, 1987 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/monroe-county-missouri. 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), Monroe County, 1987 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/monroe-county-missouri.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Median Air Quality Index (US EPA), Monroe County, 1987 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/monroe-county-missouri (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), Monroe County, 1987 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/monroe-county-missouri. 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), Monroe County, 1987 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/monroe-county-missouri
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/median-air-quality-index/monroe-county-missouri.
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 Monroe County?

Median Air Quality Index (US EPA) in Monroe County was 35 in 2025, according to the U.S. Environmental Protection Agency. That is unchanged from 2024. That is the 19th highest of 21 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 Monroe County?

51 in 2001, the highest value since 1987 in this series.

Related statistics for Monroe County

All statistics for Monroe County | Monroe County in figures