Data / Median Air Quality Index (US EPA) / St. Louis city

Median Air Quality Index (US EPA) in St. Louis city

Median Air Quality Index (US EPA) in St. Louis city was 55 in 2025, according to the U.S. Environmental Protection Agency. That is up 1 from 2024. That is the 1st highest of 21 counties in 2025.

2025, index55
Change on 2024+1
Rank1st of 21Counties in Missouri ranked
Series high851980
Series low411991

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 St. Louis city, 1980 to 2025

40506070809019801988199520022009201620251980: 85 index1982: 49 index1983: 51 index1984: 52 index1985: 50 index1986: 57 index1987: 48 index1988: 47 index1989: 45 index1990: 42 index1991: 41 index1992: 42 index1993: 42 index1994: 44 index1995: 43 index1996: 42 index1997: 42 index1998: 44 index1999: 63 index2000: 66 index2001: 65 index2002: 67 index2003: 64 index2004: 62 index2005: 70 index2006: 72 index2007: 62 index2008: 59 index2009: 58 index2010: 61 index2011: 61 index2012: 61 index2013: 57 index2014: 56 index2015: 55 index2016: 53 index2017: 52 index2018: 55 index2019: 54 index2020: 54 index2021: 55 index2022: 55 index2023: 58 index2024: 54 index2025: 55 index40608010019801996201120251980: 85 index1982: 49 index1983: 51 index1984: 52 index1985: 50 index1986: 57 index1987: 48 index1988: 47 index1989: 45 index1990: 42 index1991: 41 index1992: 42 index1993: 42 index1994: 44 index1995: 43 index1996: 42 index1997: 42 index1998: 44 index1999: 63 index2000: 66 index2001: 65 index2002: 67 index2003: 64 index2004: 62 index2005: 70 index2006: 72 index2007: 62 index2008: 59 index2009: 58 index2010: 61 index2011: 61 index2012: 61 index2013: 57 index2014: 56 index2015: 55 index2016: 53 index2017: 52 index2018: 55 index2019: 54 index2020: 54 index2021: 55 index2022: 55 index2023: 58 index2024: 54 index2025: 55 index
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 45 values
Periodindex
202555
202454
202358
202255
202155
202054
201954
201855
201752
201653
201555
201456
201357
201261
201161
201061
200958
200859
200762
200672
200570
200462
200364
200267
200165
200066
199963
199844
199742
199642
199543
199444
199342
199242
199141
199042
198945
198847
198748
198657
198550
198452
198351
198249
198085

St. Louis city 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. St. Louis city 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), St. Louis city, 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), St. Louis city, 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/st-louis-city-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), St. Louis city, 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/st-louis-city-missouri.

Harvard

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

Median Air Quality Index (US EPA) in St. Louis city was 55 in 2025, according to the U.S. Environmental Protection Agency. That is up 1 from 2024. That is the 1st 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 St. Louis city?

85 in 1980, the highest value since 1980 in this series.

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