Data / Rankings / Share of days with good air quality (US EPA AQI) / Counties in Pennsylvania

Counties in Pennsylvania by share of days with good air quality (US EPA AQI)

Lawrence County had the highest share of days with good air quality (US EPA AQI) of 38 counties in 2023, at 95.1%. Philadelphia County had the lowest, at 22.7%. The median was 64.6%. Source: EPA.

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Highest95.1Lawrence County
Lowest22.7Philadelphia County
Median64.638 counties

Map of counties, 2023

Adams County: 51.5 %Allegheny County: 33.2 %Armstrong County: 65.7 %Beaver County: 43.3 %Berks County: 56.3 %Blair County: 64 %Bradford County: 82 %Bucks County: 81.4 %Cambria County: 58.7 %Centre County: 65.5 %Chester County: 60.9 %Cumberland County: 58.1 %Dauphin County: 46.3 %Delaware County: 51.2 %Elk County: 94.5 %Erie County: 65.8 %Fayette County: 72.4 %Franklin County: 88.7 %Greene County: 72.5 %Indiana County: 72.7 %Lackawanna County: 63 %Lancaster County: 29.6 %Lawrence County: 95.1 %Lebanon County: 55.9 %Lehigh County: 63.4 %Lycoming County: 85.5 %Mercer County: 65.1 %Monroe County: 91.8 %Montgomery County: 63.6 %Northampton County: 57.7 %Philadelphia County: 22.7 %Somerset County: 91.2 %Susquehanna County: 82.9 %Tioga County: 83.6 %Washington County: 49.3 %Westmoreland County: 76.2 %Wyoming County: 84.2 %York County: 55.6 %
  • Under 51
  • 51 to 58
  • 58 to 65
  • 65 to 73
  • 73 to 84
  • 84 and over
  • No data
%, 2023. Hatched areas have no value for this period. Source: Invokely calculation with data from EPA. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2023

Lawrence County: 95.1 %Lawrence County95.1Elk County: 94.5 %Elk County94.5Monroe County: 91.8 %Monroe County91.8Somerset County: 91.2 %Somerset County91.2Franklin County: 88.7 %Franklin County88.7Lycoming County: 85.5 %Lycoming County85.5Wyoming County: 84.2 %Wyoming County84.2Tioga County: 83.6 %Tioga County83.6Susquehanna County: 82.9 %Susquehanna County82.9Bradford County: 82 %Bradford County82Bucks County: 81.4 %Bucks County81.4Westmoreland County: 76.2 %Westmoreland County76.2Indiana County: 72.7 %Indiana County72.7Greene County: 72.5 %Greene County72.5Fayette County: 72.4 %Fayette County72.4Erie County: 65.8 %Erie County65.8Armstrong County: 65.7 %Armstrong County65.7Centre County: 65.5 %Centre County65.5Mercer County: 65.1 %Mercer County65.1Blair County: 64 %Blair County64Montgomery County: 63.6 %Montgomery County63.6Lehigh County: 63.4 %Lehigh County63.4Lackawanna County: 63 %Lackawanna County63Chester County: 60.9 %Chester County60.9Cambria County: 58.7 %Cambria County58.7Cumberland County: 58.1 %Cumberland County58.1Northampton County: 57.7 %Northampton County57.7Berks County: 56.3 %Berks County56.3Lebanon County: 55.9 %Lebanon County55.9York County: 55.6 %York County55.6Adams County: 51.5 %Adams County51.5Delaware County: 51.2 %Delaware County51.2Washington County: 49.3 %Washington County49.3Dauphin County: 46.3 %Dauphin County46.3Beaver County: 43.3 %Beaver County43.3Allegheny County: 33.2 %Allegheny County33.2Lancaster County: 29.6 %Lancaster County29.6Philadelphia County: 22.7 %Philadelphia County22.7Lawrence County: 95.1 %Lawrence County95.1Elk County: 94.5 %Elk County94.5Monroe County: 91.8 %Monroe County91.8Somerset County: 91.2 %Somerset County91.2Franklin County: 88.7 %Franklin County88.7Lycoming County: 85.5 %Lycoming County85.5Wyoming County: 84.2 %Wyoming County84.2Tioga County: 83.6 %Tioga County83.6Susquehanna County: 82.9 %Susquehanna County82.9Bradford County: 82 %Bradford County82Bucks County: 81.4 %Bucks County81.4Westmoreland County: 76.2 %Westmoreland County76.2Indiana County: 72.7 %Indiana County72.7Greene County: 72.5 %Greene County72.5Fayette County: 72.4 %Fayette County72.4Erie County: 65.8 %Erie County65.8Armstrong County: 65.7 %Armstrong County65.7Centre County: 65.5 %Centre County65.5Mercer County: 65.1 %Mercer County65.1Blair County: 64 %Blair County64Montgomery County: 63.6 %Montgomery County63.6Lehigh County: 63.4 %Lehigh County63.4Lackawanna County: 63 %Lackawanna County63Chester County: 60.9 %Chester County60.9Cambria County: 58.7 %Cambria County58.7Cumberland County: 58.1 %Cumberland County58.1Northampton County: 57.7 %Northampton County57.7Berks County: 56.3 %Berks County56.3Lebanon County: 55.9 %Lebanon County55.9York County: 55.6 %York County55.6Adams County: 51.5 %Adams County51.5Delaware County: 51.2 %Delaware County51.2Washington County: 49.3 %Washington County49.3Dauphin County: 46.3 %Dauphin County46.3Beaver County: 43.3 %Beaver County43.3Allegheny County: 33.2 %Allegheny County33.2Lancaster County: 29.6 %Lancaster County29.6Philadelphia County: 22.7 %Philadelphia County22.7
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2023 (%)Change on 2022
1Lawrence County95.1+3.3 pts
2Elk County94.5-2.7 pts
3Monroe County91.8+0.7 pts
4Somerset County91.2-6.3 pts
5Franklin County88.7-6.2 pts
6Lycoming County85.5+12.8 pts
7Wyoming County84.2+3.1 pts
8Tioga County83.6+1.5 pts
9Susquehanna County82.9+4.4 pts
10Bradford County82+0.8 pts
11Bucks County81.4-1.3 pts
12Westmoreland County76.2+11.1 pts
13Indiana County72.7+0.4 pts
14Greene County72.5-6.1 pts
15Fayette County72.4+0.2 pts
16Erie County65.8-12.6 pts
17Armstrong County65.7+11.5 pts
18Centre County65.5-0.3 pts
19Mercer County65.1-13.8 pts
20Blair County64-0.5 pts
21Montgomery County63.6-1.9 pts
22Lehigh County63.4-5.1 pts
23Lackawanna County63-8.3 pts
24Chester County60.9-7.5 pts
25Cambria County58.7+11.6 pts
26Cumberland County58.1-1.1 pts
27Northampton County57.7-4.9 pts
28Berks County56.3-9.5 pts
29Lebanon County55.9-5.6 pts
30York County55.6-0.6 pts
31Adams County51.5-9 pts
32Delaware County51.2-1.1 pts
33Washington County49.3+1.9 pts
34Dauphin County46.3-7.9 pts
35Beaver County43.3-4.5 pts
36Allegheny County33.2-2.1 pts
37Lancaster County29.6+6.6 pts
38Philadelphia County22.7-19.8 pts

Other periods

About this ranking

Days with a daily Air Quality Index of 0 to 50 (good) as a percentage of the days of the year with an AQI in a US county. Calculated by Invokely from the day counts in the EPA AirData annual summaries; both counts are stored with each value.

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. 6 counties with data in other periods have no value for 2023 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: good days as a share of days with an AQI, calculated with stored counts. 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: good days as a share of days with an AQI, calculated with stored counts (Counties in Pennsylvania by share of days with good air quality (US EPA AQI), 2023) [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: good days as a share of days with an AQI, calculated with stored counts, Counties in Pennsylvania by share of days with good air quality (US EPA AQI), 2023. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/good-air-quality-days-share/pennsylvania-counties?period=2023. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. Counties in Pennsylvania by share of days with good air quality (US EPA AQI), 2023. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/good-air-quality-days-share/pennsylvania-counties?period=2023.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts, Counties in Pennsylvania by share of days with good air quality (US EPA AQI), 2023 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/good-air-quality-days-share/pennsylvania-counties?period=2023 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_pennsylvania_by_2023,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts: Counties in Pennsylvania by share of days with good air quality (US EPA AQI), 2023}},
  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/good-air-quality-days-share/pennsylvania-counties?period=2023. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. 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: good days as a share of days with an AQI, calculated with stored counts: Counties in Pennsylvania by share of days with good air quality (US EPA AQI), 2023
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/good-air-quality-days-share/pennsylvania-counties?period=2023
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/pennsylvania-counties?period=2023.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
ER  -
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Questions

Which county has the highest share of days with good air quality (US EPA AQI)?

Lawrence County, with 95.1% in 2023, according to EPA.

Which county has the lowest share of days with good air quality (US EPA AQI)?

Philadelphia County, with 22.7% in 2023.

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: good days as a share of days with an AQI, calculated with stored counts. Retrieved 2026-10-12. 6 counties have no value for 2023 and are not ranked.

Share of days with good air quality (US EPA AQI): other rankings

Counties in Pennsylvania: more rankings