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Radon Levels in Franklin County, Pennsylvania

EPA puts Franklin County in Zone 1, its highest radon zone, and high results are common there: 42.6% of the 1,059 radon tests reported to CDC (2020) came back at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    42.6%

    12.3 pts above PA

    Franklin
    42.6%
    PA
    30.3%

    1,059 tests, 2020

  • Median result

    3.1pCi/L

    Below action level

    Franklin
    3.1 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2020

  • Tests reported

    1,059

    21st of 63 by tests

    Franklin
    1,059
    Montgomery
    10,508

    Reported to CDC before any fix, 2020

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    EPA predicts over 4 pCi/L indoors

  • Rank in PA

    22 of 63

    Middle half

    Franklin
    42.6%
    Perry
    57.7%

    By share, of 63 with 30+ tests

Read a result for Franklin County

Starts at Franklin County's median, 3.1 pCi/L

3.1pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 3.1 pCi/L

Between 2 and 4 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 4 and aboveEPA says fix it

This result is between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Franklin County's median reported result, 2020.

Interpret this readingWhat a fix costs

The data

Franklin County, At a glance

Franklin County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Franklin County in and predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county. That is one forecast for the whole county, not a reading of any address in it; homes above EPA's turn up in all three zones.

USGS geologic potential: High across 94% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Franklin County, 2020

Share of reported tests at or above 4 pCi/L, by year, Franklin County
Share of reported tests at or above 4 pCi/L, by year, Franklin County
YearShare of reported tests at or above 4 pCi/L
201442.5%
201549.2%
201659.1%
201755.2%
201849.0%
201947.5%
202042.6%

2020: 42.6%. Across these years the share ran from 42.5% to 59.1%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 1,059 tests reported to CDC for Franklin County over 2020, many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.

Measured: CDC tracking data. Figure above: 2020. Measured data period: 2005 to 2020 (every CDC figure on file).

How to read these figures

Franklin County, Compared

Franklin County radon figures, compared

Calculated by Radon411

In Franklin County, about 4 in 10 reported tests in 2020 (451 of 1,059) were at or above EPA's action level. Against the national pool of 25.5%, the gap is 17.1 points higher. Across 67 Pennsylvania counties pooled together, 30.3% of tests reached that level, so Franklin County runs 12.3 points above its state.

Of 5 neighbours with a figure, 4 reported a larger share at or above 4 pCi/L and 1 a smaller one; the spread is 39.7% (Adams County) to 57.7% (Perry County). By share, Franklin County is 22nd of 63 Pennsylvania counties with 30 or more tests for the same period.

Year by year, 2014 opened at 42.5% and 2020 closed at 42.6% (about level), with 2016 the high at 59.1%. Half the tests came in under 3.1 pCi/L and half over it; the single highest reached 165.6 pCi/L. Below the action level, 395 tests (37.3%) came in under 2 pCi/L, against 44.3% statewide, and 213 tests (20.1%) fell between 2 and 4, against 25.4% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 42.6% share point the same way here. USGS geology rates 94% of the county's land high radon potential.

The busiest year on file was 2014, with 1,246 tests reported; the quietest, 2017, had 960.

Share of reported tests at or above 4 pCi/L by year, Franklin County against Pennsylvania2014 to 2020, years with 30 or more tests: Franklin County 42.5% to 42.6%, the state's pooled share 30.3% in 2020.
Franklin CountyPennsylvania, pooled
Share of reported tests at or above 4 pCi/L by year, Franklin County against Pennsylvania: data table
YearTestsFranklin County, at or above 4 pCi/LPennsylvania, pooled
20141,24642.5%36.1%
20151,12649.2%37.8%
201697259.1%34.4%
201796055.2%35.1%
20181,00249.0%30.5%
20191,10747.5%31.4%
20201,05942.6%30.3%
Franklin County against Pennsylvania, the United States and nearby counties, 2020
AreaTestsAt or above 4 pCi/LMedianDifference from Franklin County
Franklin County1,05942.6%3.1 pCi/LThis county
Pennsylvania, pooled67 counties, pooled93,66930.3%Not pooled−12.3 points
United States, pooled915 counties, pooled405,35525.5%Not pooled−17.1 points
Lebanon Countyhighest in the state1,10254.2%4.8 pCi/L+11.6 points
Philadelphia Countylowest in the state8,44210.6%1.7 pCi/L−32.0 points
Fulton County, PAborders it2867.9%8.3 pCi/L+25.3 points
Perry County, PAborders it18957.7%4.9 pCi/L+15.1 points
Huntingdon County, PAborders it10054.0%4.5 pCi/L+11.4 points
Juniata County, PAborders it8752.9%4.4 pCi/L+10.3 points
Cumberland County, PAborders it2,95043.6%3.1 pCi/L+1.0 points
Adams County, PAborders it85239.7%2.8 pCi/L−2.9 points
Where Franklin County's reported results fell, 2020, beside Pennsylvania and the United States
ResultFranklin County testsFranklin County sharePennsylvania shareU.S. shareAgainst Pennsylvania
Under 2 pCi/L39537.3%44.3%51.6%−7.0 points
2 to 4 pCi/L21320.1%25.4%22.9%−5.3 points
4 pCi/L and above45142.6%30.3%25.5%+12.3 points
Franklin County ranked among the 63 Pennsylvania counties with 30 or more tests, by share at or above 4 pCi/L, 2020
CountyRankTestsAt or above 4 pCi/LMedian
Indiana County17 of 6322844.3%3.6 pCi/L
Somerset County18 of 6312643.7%3.7 pCi/L
Cumberland County19 of 632,95043.6%3.1 pCi/L
Bradford County20 of 6328643.4%3.4 pCi/L
Lancaster County21 of 634,39843.3%3.0 pCi/L
Franklin County22 of 631,05942.6%3.1 pCi/L
Snyder County23 of 639942.4%2.8 pCi/L
Beaver County24 of 6386842.4%3.2 pCi/L
Butler County25 of 631,49242.3%3.3 pCi/L
Blair County26 of 6342442.0%3.2 pCi/L
Montour County27 of 6312341.5%3.1 pCi/L
Franklin County radon tests by year, against Pennsylvania's pooled share
YearTestsAt or above 4 pCi/LMedianHighestPennsylvania, pooledChange from the row before
20201,05942.6%3.1 pCi/L165.6 pCi/L30.3%−4.9 points
20191,10747.5%3.6 pCi/L117.7 pCi/L31.4%−1.5 points
20181,00249.0%3.8 pCi/L170.2 pCi/L30.5%−6.2 points
201796055.2%4.5 pCi/L111.7 pCi/L35.1%−3.9 points
201697259.1%5.1 pCi/L156.5 pCi/L34.4%+9.9 points
20151,12649.2%3.8 pCi/L293.9 pCi/L37.8%+6.7 points
20141,24642.5%3.1 pCi/L128.9 pCi/L36.1%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Franklin County, State data

Pennsylvania's own radon test data

Measured

What Pennsylvania's own agencies publish about radon tests in Franklin County, with their period. These are not CDC's figures and are never added to them.

MeasuredState figures, not CDC's

What Pennsylvania DEP reports for the ZIP codes in Franklin County

Pennsylvania DEP publishes its figures by ZIP code, not by county. These are the 31 ZIP codes that lie wholly or partly in Franklin County, each with the state's own figures for it. Period: Period not stated by DEP.

ZIP codes in Franklin County
ZIP codeWhat the state reports
17021Basement: figures not shown; First floor: figures not shown
17201Basement: average 10.1 pCi/L, 4,153 tests; First floor: average 6.5 pCi/L, 729 tests
17202Basement: average 10.7 pCi/L, 1,999 tests; First floor: average 6.1 pCi/L, 235 tests
17210Basement: figures not shown; First floor: figures not shown
17214Basement: average 5.1 pCi/L, 64 tests; First floor: figures not shown
17217Basement: figures not shown; First floor: figures not shown
17219Basement: figures not shown; First floor: figures not shown
17220Basement: figures not shown; First floor: figures not shown
17221Basement: figures not shown; First floor: figures not shown
17222Basement: average 7.7 pCi/L, 1,614 tests; First floor: average 4.6 pCi/L, 227 tests
17224Basement: average 6.6 pCi/L, 67 tests; First floor: figures not shown
17225Basement: average 11.4 pCi/L, 1,554 tests; First floor: average 5.8 pCi/L, 240 tests
17232Basement: figures not shown; First floor: figures not shown
17235Basement: figures not shown; First floor: figures not shown
17236Basement: average 10.8 pCi/L, 559 tests; First floor: average 3.3 pCi/L, 189 tests
17237Basement: average 5.3 pCi/L, 74 tests; First floor: figures not shown
17240Basement: average 10.4 pCi/L, 228 tests; First floor: average 4.5 pCi/L, 37 tests
17244Basement: average 11.3 pCi/L, 131 tests; First floor: figures not shown
17246Basement: figures not shown; First floor: figures not shown
17247Basement: figures not shown; First floor: figures not shown
17250Basement: figures not shown
17251Basement: figures not shown; First floor: figures not shown
17252Basement: average 12.9 pCi/L, 170 tests; First floor: figures not shown
17254Basement: average 8.1 pCi/L, 53 tests; First floor: figures not shown
17257Basement: average 10.5 pCi/L, 2,605 tests; First floor: average 4.6 pCi/L, 796 tests
17261Basement: figures not shown; First floor: figures not shown
17262Basement: figures not shown; First floor: figures not shown
17263Basement: figures not shown; First floor: figures not shown
17265Basement: figures not shown; First floor: figures not shown
17268Basement: average 10.5 pCi/L, 2,247 tests; First floor: average 4.6 pCi/L, 407 tests
17271Basement: figures not shown; First floor: figures not shown
  • DEP's report gives the number of tests, the highest result and the average result for each floor tested; it states no period.
  • DEP says the smartest thing to do is to test your home for radon, no matter where you live.
  • A ZIP code that crosses the county line is listed whole; its figures cover all of it.

Measured: Pennsylvania DEP data, Period not stated by DEP.

Franklin County, Geology

The ground under Franklin County

Predicted

Most of the ground under Franklin County is one class on USGS's geologic map: 93.8% of its land is high radon potential, with 6.2% low. The map puts 66.8% of Franklin County in the area it calls Great Valley Section and 26.7% in Appalachian Mountain Section, with one smaller area beside them. USGS gives the first a radon index of 15 and the second 12, both in the high band (12 to 17).

USGS's geologic areas under Franklin County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Great Valley SectionSandstone, shale and siltstone.High1566.8%
Appalachian Mountain SectionPaleozoic sandstone, shale, and limestone.High1226.7%
Blue Ridge Gettysburg BasinMetasedimentary and metavolcanic rocks.Low86.2%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Franklin County beside the ground around it

Franklin County has more high-potential ground than Pennsylvania as a whole: 93.8% of its land against 70.4%. Of the 8 counties that border it, 5 have more high-potential ground, Fulton County the most at 100%.

Share of land by USGS radon potential: Franklin County, the 8 counties bordering it and Pennsylvania
AreaEPA zoneLow potentialModerate potentialHigh potential
Franklin CountyZone 16.2%None93.8%
Cumberland CountyZone 119.1%None80.9%
Fulton CountyZone 1NoneNone100%
Adams CountyZone 127.7%None72.3%
Juniata CountyZone 1NoneNone100%
Huntingdon CountyZone 1NoneNone100%
Washington County, MDZone 14.4%None95.6%
Perry CountyZone 1NoneNone100%
Frederick County, MDZone 133.5%19.1%47.4%
Pennsylvania67 counties, pooled by land areaVaries0.7%28.9%70.4%

The map rates the ground, not the air in any home.

Local help

Franklin County, Local resources

Radon testing and mitigation in Franklin County

Listed radon businesses with an address in Franklin County:

Listed radon professionals by town: Chambersburg

What Pennsylvania's program says
Phone
800-237-2366
Licensing of radon professionals
The Radon Certification Act requires DEP to establish by regulation, a certification program for persons conducting radon gas and radon progeny testing, laboratory analysis and mitigation of radon contamination in buildings.

What it means

Franklin County, Questions

Questions about radon in Franklin County

Are radon levels high in Franklin County?

In 2020, 42.6% of the radon tests reported to CDC for Franklin County, Pennsylvania were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.1 pCi/L. Of 63 Pennsylvania counties with 30 or more tests for the same period, 21 reported a higher share; pooled, the state comes to 30.3%.

Which counties border Franklin County?

Franklin County borders 8 counties: Cumberland County, PA, Fulton County, PA, Adams County, PA, Juniata County, PA, Huntingdon County, PA, Washington County, MD, Perry County, PA and Frederick County, MD.

Products

Franklin County, Products

Testing a home in Franklin County

In Franklin County, 42.6% of 1,059 tests reported to CDC in 2020 reached 4 pCi/L, against 30.3% pooled across Pennsylvania. In Zone 1 the year-round level in Franklin County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.

Test kits and monitors3

See every kit and monitor

Franklin County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Franklin County

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Franklin County, Bordering counties

Counties bordering Franklin County

Calculated by Radon411

Franklin County, Cities and towns

Cities and towns in Franklin County

The Census Bureau estimates 160,652 residents in Franklin County for July 1, 2025, 4,714 more than in 2020 (+3.0%). That works out to 208 people per square mile of land. No town dominates: Chambersburg, the largest, has 23,376 residents, 14.6% of the total. CDC's 1,059 reported tests for 2020 work out to 6.6 per 1,000 residents (2025 estimate), close to Pennsylvania's 7.2.

From Chambersburg to Orrstown, CDC publishes no figure by town: each reads Franklin County's.

The cities and towns in Franklin County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Chambersburg23,376+6.8%14.6%
Waynesboro11,190+1.6%7.0%
Shippensburgextends beyond Franklin County5,615+2.5%Counted whole
Greencastle4,222Level2.6%
Mont Alto1,563−0.8%1.0%
Mercersburg1,492−0.9%0.9%
Orrstown210−1.9%0.1%

7 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Franklin County is counted whole, so it has no share.

Franklin County, Homes

Homes in Franklin County

Of Franklin County's 66,787 homes, 68% are detached houses, against 57% across Pennsylvania; 6% are in buildings of five or more homes. Much of Franklin County is recent building: 22% of its homes have gone up since 2000 and the middle year built is 1978, against 1965 for Pennsylvania. 73% of occupied homes are lived in by their owner (Pennsylvania: 69%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Franklin County, Pennsylvania, 2019 to 2023
HomesFranklin CountyPennsylvania
Housing units66,7875,779,663
Detached houses68%57%
In buildings of 5 or more6%13%
Mobile homes6%4%
Built before 196030%45%
Built since 200022%14%
Middle year built19781965
Owner-occupied73%69%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.