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)

Bradford County had the highest share of days with good air quality (US EPA AQI) of 38 counties in 2014, at 100%. Philadelphia County had the lowest, at 13.7%. The median was 43.4%. Source: EPA.

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Highest100Bradford County
Lowest13.7Philadelphia County
Median43.438 counties

Map of counties, 2014

Adams County: 60.8 %Allegheny County: 27.1 %Armstrong County: 37.6 %Beaver County: 41.1 %Berks County: 42.5 %Blair County: 41.4 %Bradford County: 100 %Bucks County: 40 %Cambria County: 41.4 %Centre County: 48.5 %Chester County: 42.4 %Clearfield County: 95.1 %Cumberland County: 38.7 %Dauphin County: 40.8 %Delaware County: 26.3 %Elk County: 94.2 %Erie County: 42.6 %Franklin County: 92.3 %Greene County: 90.3 %Indiana County: 91.8 %Lackawanna County: 50.7 %Lancaster County: 15.9 %Lawrence County: 92.3 %Lebanon County: 35.1 %Lehigh County: 91.5 %Luzerne County: 94.5 %Lycoming County: 94.2 %Mercer County: 31.2 %Monroe County: 58.2 %Montgomery County: 57.5 %Northampton County: 40.5 %Perry County: 94 %Philadelphia County: 13.7 %Somerset County: 95.6 %Tioga County: 90.1 %Washington County: 21.6 %Westmoreland County: 44.1 %York County: 42.5 %
  • Under 36
  • 36 to 41
  • 41 to 43
  • 43 to 80
  • 80 to 94
  • 94 and over
  • No data
%, 2014. 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, 2014

Bradford County: 100 %Bradford County100Somerset County: 95.6 %Somerset County95.6Clearfield County: 95.1 %Clearfield County95.1Luzerne County: 94.5 %Luzerne County94.5Elk County: 94.2 %Elk County94.2Lycoming County: 94.2 %Lycoming County94.2Perry County: 94 %Perry County94Franklin County: 92.3 %Franklin County92.3Lawrence County: 92.3 %Lawrence County92.3Indiana County: 91.8 %Indiana County91.8Lehigh County: 91.5 %Lehigh County91.5Greene County: 90.3 %Greene County90.3Tioga County: 90.1 %Tioga County90.1Adams County: 60.8 %Adams County60.8Monroe County: 58.2 %Monroe County58.2Montgomery County: 57.5 %Montgomery County57.5Lackawanna County: 50.7 %Lackawanna County50.7Centre County: 48.5 %Centre County48.5Westmoreland County: 44.1 %Westmoreland County44.1Erie County: 42.6 %Erie County42.6Berks County: 42.5 %Berks County42.5York County: 42.5 %York County42.5Chester County: 42.4 %Chester County42.4Blair County: 41.4 %Blair County41.4Cambria County: 41.4 %Cambria County41.4Beaver County: 41.1 %Beaver County41.1Dauphin County: 40.8 %Dauphin County40.8Northampton County: 40.5 %Northampton County40.5Bucks County: 40 %Bucks County40Cumberland County: 38.7 %Cumberland County38.7Armstrong County: 37.6 %Armstrong County37.6Lebanon County: 35.1 %Lebanon County35.1Mercer County: 31.2 %Mercer County31.2Allegheny County: 27.1 %Allegheny County27.1Delaware County: 26.3 %Delaware County26.3Washington County: 21.6 %Washington County21.6Lancaster County: 15.9 %Lancaster County15.9Philadelphia County: 13.7 %Philadelphia County13.7Bradford County: 100 %Bradford County100Somerset County: 95.6 %Somerset County95.6Clearfield County: 95.1 %Clearfield County95.1Luzerne County: 94.5 %Luzerne County94.5Elk County: 94.2 %Elk County94.2Lycoming County: 94.2 %Lycoming County94.2Perry County: 94 %Perry County94Franklin County: 92.3 %Franklin County92.3Lawrence County: 92.3 %Lawrence County92.3Indiana County: 91.8 %Indiana County91.8Lehigh County: 91.5 %Lehigh County91.5Greene County: 90.3 %Greene County90.3Tioga County: 90.1 %Tioga County90.1Adams County: 60.8 %Adams County60.8Monroe County: 58.2 %Monroe County58.2Montgomery County: 57.5 %Montgomery County57.5Lackawanna County: 50.7 %Lackawanna County50.7Centre County: 48.5 %Centre County48.5Westmoreland County: 44.1 %Westmoreland County44.1Erie County: 42.6 %Erie County42.6Berks County: 42.5 %Berks County42.5York County: 42.5 %York County42.5Chester County: 42.4 %Chester County42.4Blair County: 41.4 %Blair County41.4Cambria County: 41.4 %Cambria County41.4Beaver County: 41.1 %Beaver County41.1Dauphin County: 40.8 %Dauphin County40.8Northampton County: 40.5 %Northampton County40.5Bucks County: 40 %Bucks County40Cumberland County: 38.7 %Cumberland County38.7Armstrong County: 37.6 %Armstrong County37.6Lebanon County: 35.1 %Lebanon County35.1Mercer County: 31.2 %Mercer County31.2Allegheny County: 27.1 %Allegheny County27.1Delaware County: 26.3 %Delaware County26.3Washington County: 21.6 %Washington County21.6Lancaster County: 15.9 %Lancaster County15.9Philadelphia County: 13.7 %Philadelphia County13.7
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2014 (%)Change on 2013
1Bradford County100+0.7 pts
2Somerset County95.6+3.1 pts
3Clearfield County95.1+4.9 pts
4Luzerne County94.5+1.6 pts
5Elk County94.2+2.2 pts
5Lycoming County94.2+2.8 pts
7Perry County94+3.9 pts
8Franklin County92.3+11.2 pts
8Lawrence County92.3-0.6 pts
10Indiana County91.8+5.2 pts
11Lehigh County91.5+4.7 pts
12Greene County90.3+0.6 pts
13Tioga County90.1+0.8 pts
14Adams County60.8+13.4 pts
15Monroe County58.2+3.4 pts
16Montgomery County57.5+2.4 pts
17Lackawanna County50.7-6.3 pts
18Centre County48.5-9 pts
19Westmoreland County44.1+10.4 pts
20Erie County42.6+7 pts
21Berks County42.5+6.3 pts
21York County42.5-3.8 pts
23Chester County42.4+0.2 pts
24Blair County41.4+8.5 pts
24Cambria County41.4+4.7 pts
26Beaver County41.10 pts
27Dauphin County40.8+2.7 pts
28Northampton County40.5+6 pts
29Bucks County40-4.7 pts
30Cumberland County38.70 pts
31Armstrong County37.6+2.3 pts
32Lebanon County35.1-11.2 pts
33Mercer County31.2-8 pts
34Allegheny County27.1+0.3 pts
35Delaware County26.3-11.8 pts
36Washington County21.6-9.1 pts
37Lancaster County15.9-25.7 pts
38Philadelphia County13.7-12.9 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 2014 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), 2014) [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), 2014. 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=2014. 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), 2014. 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=2014.

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), 2014 [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=2014 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_pennsylvania_by_2014,
  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), 2014}},
  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=2014. 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), 2014
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=2014
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/pennsylvania-counties?period=2014.
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)?

Bradford County, with 100% in 2014, according to EPA.

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

Philadelphia County, with 13.7% in 2014.

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 2014 and are not ranked.

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

Counties in Pennsylvania: more rankings