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

Median Air Quality Index (US EPA) in Franklin County

Median Air Quality Index (US EPA) in Franklin County was 37 in 2025, according to the U.S. Environmental Protection Agency. That is up 2 from 2024. That is the 28th highest of 38 counties in 2025.

2025, index37
Change on 2024+2
Rank28th of 38Counties in Pennsylvania ranked
Series high671998
Series low322018

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 Franklin County, 1996 to 2025

304050607019962001200620112016202120251996: 48 index1997: 54 index1998: 67 index1999: 64 index2000: 47 index2001: 64 index2002: 67 index2003: 46 index2004: 44 index2005: 45 index2006: 42 index2007: 48 index2008: 43 index2009: 37 index2010: 45 index2011: 41 index2012: 40 index2013: 40 index2014: 38 index2015: 34 index2016: 33 index2017: 33 index2018: 32 index2019: 36 index2020: 32 index2021: 35 index2022: 39 index2023: 39 index2024: 35 index2025: 37 index304050607019962006201620251996: 48 index1997: 54 index1998: 67 index1999: 64 index2000: 47 index2001: 64 index2002: 67 index2003: 46 index2004: 44 index2005: 45 index2006: 42 index2007: 48 index2008: 43 index2009: 37 index2010: 45 index2011: 41 index2012: 40 index2013: 40 index2014: 38 index2015: 34 index2016: 33 index2017: 33 index2018: 32 index2019: 36 index2020: 32 index2021: 35 index2022: 39 index2023: 39 index2024: 35 index2025: 37 index
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 30 values
Periodindex
202537
202435
202339
202239
202135
202032
201936
201832
201733
201633
201534
201438
201340
201240
201141
201045
200937
200843
200748
200642
200545
200444
200346
200267
200164
200047
199964
199867
199754
199648

Franklin County compared with nearby places

Adams County: 42 indexAllegheny County: 52 indexArmstrong County: 41 indexBeaver County: 46 indexBerks County: 43 indexBlair County: 40 indexBradford County: 37 indexBucks County: 36 indexCambria County: 41 indexCentre County: 41 indexChester County: 43 indexCumberland County: 35 indexDauphin County: 44 indexDelaware County: 44 indexElk County: 36 indexErie County: 34 indexFayette County: 40 indexFranklin County: 37 indexGreene County: 40 indexIndiana County: 39 indexLackawanna County: 39 indexLancaster County: 45 indexLebanon County: 42 indexLehigh County: 41 indexLycoming County: 40 indexMercer County: 42 indexMonroe County: 36 indexMontgomery County: 41 indexNorthampton County: 38 indexPhiladelphia County: 50 indexSomerset County: 36 indexSusquehanna County: 22 indexTioga County: 39 indexWarren County: 35 indexWashington County: 44 indexWestmoreland County: 39 indexWyoming County: 24 indexYork County: 45 index
  • Under 36
  • 36 to 39
  • 39 to 40
  • 40 to 42
  • 42 to 44
  • 44 and over
  • No data
Median Air Quality Index (US EPA), 2025, index. Franklin 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), Franklin County, 1996 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), Franklin County, 1996 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/franklin-county-pennsylvania. 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), Franklin County, 1996 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/franklin-county-pennsylvania.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Median Air Quality Index (US EPA), Franklin County, 1996 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/franklin-county-pennsylvania (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), Franklin County, 1996 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/franklin-county-pennsylvania. 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), Franklin County, 1996 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/franklin-county-pennsylvania
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/median-air-quality-index/franklin-county-pennsylvania.
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 Franklin County?

Median Air Quality Index (US EPA) in Franklin County was 37 in 2025, according to the U.S. Environmental Protection Agency. That is up 2 from 2024. That is the 28th highest of 38 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 Franklin County?

67 in 1998, the highest value since 1996 in this series.

Related statistics for Franklin County

All statistics for Franklin County | Franklin County in figures