Data / Rankings / Median Air Quality Index (US EPA) / Counties in Pennsylvania

Counties in Pennsylvania by median Air Quality Index (US EPA)

Allegheny County had the highest median Air Quality Index (US EPA) of 37 counties in 2016, at 56. Lawrence County had the lowest, at 33. The median was 45. Source: the U.S. Environmental Protection Agency.

Keep it in a collection in your library.
Highest56Allegheny County
Lowest33Lawrence County
Median4537 counties

Map of counties, 2016

Adams County: 44 indexAllegheny County: 56 indexArmstrong County: 53 indexBeaver County: 52 indexBerks County: 54 indexBlair County: 44 indexBradford County: 43 indexBucks County: 34 indexCambria County: 46 indexCentre County: 45 indexChester County: 52 indexClearfield County: 38 indexCumberland County: 51 indexDauphin County: 50 indexDelaware County: 55 indexElk County: 37 indexErie County: 44 indexFranklin County: 33 indexGreene County: 39 indexIndiana County: 38 indexLackawanna County: 45 indexLancaster County: 56 indexLawrence County: 33 indexLebanon County: 55 indexLehigh County: 52 indexLuzerne County: 34 indexLycoming County: 34 indexMercer County: 48 indexMonroe County: 43 indexMontgomery County: 34 indexNorthampton County: 53 indexPhiladelphia County: 55 indexSomerset County: 36 indexTioga County: 41 indexWashington County: 55 indexWestmoreland County: 53 indexYork County: 51 index
  • Under 36
  • 36 to 43
  • 43 to 45
  • 45 to 52
  • 52 to 54
  • 54 and over
  • No data
index, 2016. Hatched areas have no value for this period. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2016

Allegheny County: 56 indexAllegheny County56Lancaster County: 56 indexLancaster County56Delaware County: 55 indexDelaware County55Lebanon County: 55 indexLebanon County55Philadelphia County: 55 indexPhiladelphia County55Washington County: 55 indexWashington County55Berks County: 54 indexBerks County54Armstrong County: 53 indexArmstrong County53Northampton County: 53 indexNorthampton County53Westmoreland County: 53 indexWestmoreland County53Beaver County: 52 indexBeaver County52Chester County: 52 indexChester County52Lehigh County: 52 indexLehigh County52Cumberland County: 51 indexCumberland County51York County: 51 indexYork County51Dauphin County: 50 indexDauphin County50Mercer County: 48 indexMercer County48Cambria County: 46 indexCambria County46Centre County: 45 indexCentre County45Lackawanna County: 45 indexLackawanna County45Adams County: 44 indexAdams County44Blair County: 44 indexBlair County44Erie County: 44 indexErie County44Bradford County: 43 indexBradford County43Monroe County: 43 indexMonroe County43Tioga County: 41 indexTioga County41Greene County: 39 indexGreene County39Clearfield County: 38 indexClearfield County38Indiana County: 38 indexIndiana County38Elk County: 37 indexElk County37Somerset County: 36 indexSomerset County36Bucks County: 34 indexBucks County34Luzerne County: 34 indexLuzerne County34Lycoming County: 34 indexLycoming County34Montgomery County: 34 indexMontgomery County34Franklin County: 33 indexFranklin County33Lawrence County: 33 indexLawrence County33Allegheny County: 56 indexAllegheny County56Lancaster County: 56 indexLancaster County56Delaware County: 55 indexDelaware County55Lebanon County: 55 indexLebanon County55Philadelphia County: 55 indexPhiladelphia County55Washington County: 55 indexWashington County55Berks County: 54 indexBerks County54Armstrong County: 53 indexArmstrong County53Northampton County: 53 indexNorthampton County53Westmoreland County: 53 indexWestmoreland County53Beaver County: 52 indexBeaver County52Chester County: 52 indexChester County52Lehigh County: 52 indexLehigh County52Cumberland County: 51 indexCumberland County51York County: 51 indexYork County51Dauphin County: 50 indexDauphin County50Mercer County: 48 indexMercer County48Cambria County: 46 indexCambria County46Centre County: 45 indexCentre County45Lackawanna County: 45 indexLackawanna County45Adams County: 44 indexAdams County44Blair County: 44 indexBlair County44Erie County: 44 indexErie County44Bradford County: 43 indexBradford County43Monroe County: 43 indexMonroe County43Tioga County: 41 indexTioga County41Greene County: 39 indexGreene County39Clearfield County: 38 indexClearfield County38Indiana County: 38 indexIndiana County38Elk County: 37 indexElk County37Somerset County: 36 indexSomerset County36Bucks County: 34 indexBucks County34Luzerne County: 34 indexLuzerne County34Lycoming County: 34 indexLycoming County34Montgomery County: 34 indexMontgomery County34Franklin County: 33 indexFranklin County33Lawrence County: 33 indexLawrence County33
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2016
index		Change on 2015
1Allegheny County56-2
1Lancaster County560
3Delaware County550
3Lebanon County55+3
3Philadelphia County55-1
3Washington County550
7Berks County540
8Armstrong County530
8Northampton County53-3
8Westmoreland County53+1
11Beaver County52+1
11Chester County52-3
11Lehigh County52+18
14Cumberland County51-3
14York County51-4
16Dauphin County50-6
17Mercer County48-5
18Cambria County46-8
19Centre County45-1
19Lackawanna County45-6
21Adams County44-7
21Blair County44-8
21Erie County440
24Bradford County43+11
24Monroe County43+1
26Tioga County41-3
27Greene County39+2
28Clearfield County380
28Indiana County38+1
30Elk County37+1
31Somerset County36+2
32Bucks County34-19
32Luzerne County340
32Lycoming County340
32Montgomery County34-13
36Franklin County33-1
36Lawrence County330

Other periods

About this ranking

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.

Every value in the ranking comes from the same publisher and the same period, so the counties are compared on one definition. 7 counties with data in other periods have no value for 2016 and are left out rather than filled from another source. Equal values share a rank.

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 (Counties in Pennsylvania by median Air Quality Index (US EPA), 2016) [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, Counties in Pennsylvania by median Air Quality Index (US EPA), 2016. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/median-air-quality-index/pennsylvania-counties?period=2016. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Counties in Pennsylvania by median Air Quality Index (US EPA), 2016. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/median-air-quality-index/pennsylvania-counties?period=2016.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Counties in Pennsylvania by median Air Quality Index (US EPA), 2016 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/median-air-quality-index/pennsylvania-counties?period=2016 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_pennsylvania_by_2016,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Counties in Pennsylvania by median Air Quality Index (US EPA), 2016}},
  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/rankings/median-air-quality-index/pennsylvania-counties?period=2016. 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: Counties in Pennsylvania by median Air Quality Index (US EPA), 2016
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/rankings/median-air-quality-index/pennsylvania-counties?period=2016
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/pennsylvania-counties?period=2016.
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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Rank Counties in Pennsylvania by median Air Quality Index (US EPA) using official data, and cite the source.
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Questions

Which county has the highest median Air Quality Index (US EPA)?

Allegheny County, with 56 in 2016, according to the U.S. Environmental Protection Agency.

Which county has the lowest median Air Quality Index (US EPA)?

Lawrence County, with 33 in 2016.

Where does this ranking come from?

Every value comes from one source and one period, so the places are comparable: U.S. Environmental Protection Agency, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12. 7 counties have no value for 2016 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Pennsylvania: more rankings