Radon Testing & Mitigation in Franklin County, PA
59% of 20,716 basement radon tests reported to PA DEP in Franklin County measured 4.0 pCi/L or higher, EPA's action level (median 5.2 pCi/L).
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Radon in Franklin County: 59% of the 20,716 basement tests reported to PA DEP measured 4.0 pCi/L or higher, EPA's action level, 22 points above the 37% statewide share. The county ranks 6th highest of 67, and the median result is 5.2 pCi/L. Only a test shows one home's level.
Radon Test Results by ZIP Code in Franklin County
20 ZIP codes in Franklin County have at least 20 basement tests on record. Among those with 100 or more, the highest share at or above 4.0 pCi/L is in 17244 (Orrstown): 67% of 184 tests. The lowest is in 17214 (Blue Ridge Summit): 32% of 104 tests.
| ZIP code | Post office | Basement tests | Median pCi/L | At or above 4.0 |
|---|---|---|---|---|
| 17201 | Chambersburg | 5,247 | 5.4 | 60% |
| 17202 | Chambersburg | 3,720 | 5.2 | 58% |
| 17268 | Waynesboro | 3,602 | 5.0 | 58% |
| 17225 | Greencastle | 2,546 | 6.1 | 61% |
| 17222 | Fayetteville | 2,414 | 4.4 | 54% |
| 17257 | Shippensburg (part) | 1,202 | 6.1 | 60% |
| 17236 | Mercersburg | 806 | 6.1 | 65% |
| 17252 | Saint Thomas | 311 | 5.7 | 63% |
| 17244 | Orrstown | 184 | 6.1 | 67% |
| 17237 | Mont Alto | 113 | 3.7 | 48% |
| 17214 | Blue Ridge Summit | 104 | 2.8 | 32% |
| 17224 | Fort Loudon | 102 | 4.7 | 57% |
| 17254 | Scotland | 64 | 4.1 | 50% |
| 17262 | Spring Run | 37 | 5.2 | 65% |
| 17235 | Marion | 24 | 11.7 | 71% |
Show all 20 ZIP codes
| 17263 | State Line | 24 | 9.3 | 71% |
| 17265 | Upperstrasburg | 24 | 6.6 | 63% |
| 17271 | Willow Hill | 24 | 5.6 | 50% |
| 17220 | Dry Run | 21 | 14.7 | 76% |
| 17240 | Newburg (part) | 21 | 14.2 | 76% |
| Franklin County | 20,716 | 5.2 | 59% | |
| Pennsylvania | 2,629,492 | 2.8 | 37% | |
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Get matched with a DEP-certified radon professionalFirst-floor tests in Franklin County: 3,417 on record, median 2.6 pCi/L, 37% at or above 4.0 pCi/L.
EPA's Map of Radon Zones (1993) places Franklin County in Zone 1, its highest category (predicted average indoor screening level above 4 pCi/L). The map is a county-wide prediction; the figures in this table are measurements.
Figures count tests, not homes. A home tested more than once is counted each time, and tests run after a mitigation system was installed are included because the dataset does not separate them. ZIP codes with fewer than 20 basement tests are not shown.
Housing Age in Franklin County
53% of Franklin County's 67,157 housing units were built before 1980, 14 points below the 67% statewide figure; 16% date from before 1940. Those homes predate EPA's 1994 model standards for radon-resistant construction. Age does not predict a test result: EPA's guidance is that any home, new or old, may have a radon problem.
Source: U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates, table B25034. Counts all housing units, including vacant and seasonal ones. Retrieved September 29, 2026.
Bedrock Under Franklin County
Martinsburg Formation (Ordovician; shale) underlies 34% of the county. Rockdale Run Formation (Ordovician; limestone) underlies 7% of the county. St. Paul Group (Ordovician; limestone) underlies 7% of the county.
Limestone and dolomite are usually low in uranium themselves, but the soils left behind as the rock dissolves are often enriched in uranium and radium, and solution cavities in the rock give soil gas extra pathways.
Mapped bedrock describes an area. The USGS states that its radon assessment cannot be applied to individual homes. More on Pennsylvania radon and geology.
Sources: U.S. Geological Survey State Geologic Map Compilation, from Pennsylvania Geological Survey Map 1 (1980; digital edition 2001). Retrieved September 29, 2026. U.S. Geological Survey Open-File Report 93-292-C, Geologic Radon Potential of EPA Region 3 (1993).
Home Purchases in Franklin County
Lenders reported 1,676 home-purchase mortgages originated in Franklin County in 2024. The count covers financed purchases only; cash purchases are not in the data. See radon in a Pennsylvania home sale.
Source: FFIEC Home Mortgage Disclosure Act data, 2024. Retrieved September 29, 2026.
Municipalities in Franklin County
Franklin County has 22 municipalities: 7 boroughs and 15 townships.
Show all 22 municipalities
Antrim township, Chambersburg borough, Fannett township, Greencastle borough, Greene township, Guilford township, Hamilton township, Letterkenny township, Lurgan township, Mercersburg borough, Metal township, Mont Alto borough, Montgomery township, Orrstown borough, Peters township, Quincy township, Shippensburg borough, Southampton township, St. Thomas township, Warren township, Washington township, Waynesboro borough.
Source: U.S. Census Bureau, 2025 Gazetteer Files, county subdivisions. Retrieved September 29, 2026.
City Pages in Franklin County
Neighboring Counties
- Radon in Adams County → 44% of 16,613 basement tests at or above 4.0 pCi/L
- Radon in Cumberland County → 55% of 76,003 basement tests at or above 4.0 pCi/L
- Radon in Fulton County → 70% of 706 basement tests at or above 4.0 pCi/L
- Radon in Huntingdon County → 53% of 3,957 basement tests at or above 4.0 pCi/L
- Radon in Juniata County → 62% of 1,798 basement tests at or above 4.0 pCi/L
- Radon in Perry County → 62% of 5,945 basement tests at or above 4.0 pCi/L
- All 67 Pennsylvania county radon pages
DEP-Certified Mitigation Firms Based in County
No DEP-certified mitigation firms are physically based in Franklin County. Certified professionals from adjacent counties travel here to perform testing and mitigation.
Source: PA DEP Certified Mitigation Firms Directory, July 2026. This reflects business address only — firms based elsewhere may also serve Franklin County.
Testing, Cost and Certification
Short-term tests run 48–96 hours; long-term tests run 90 days or more. At 4.0 pCi/L or higher, retest or mitigate. How radon testing works in a Pennsylvania real estate transaction.
Mitigation in Franklin County typically costs $900–$2,050. Pennsylvania radon mitigation cost guide.
Anyone testing or mitigating for pay must hold DEP certification under 25 Pa. Code § 240. How to verify a contractor in the PA DEP Radon Services Directory.
Frequently Asked Questions
What share of radon tests in Franklin County are at or above the EPA action level?
59% of the 20,716 basement tests reported to PA DEP from Franklin County measured 4.0 pCi/L or higher, against 37% statewide. The median result is 5.2 pCi/L, and 12% of tests measured 20 pCi/L or higher.
Which Franklin County ZIP code has the highest radon test results?
Among ZIP codes with at least 100 basement tests, 17244 (Orrstown) has the highest share at or above 4.0 pCi/L: 67% of 184 tests, with a median of 6.1 pCi/L. 17214 (Blue Ridge Summit) has the lowest, at 32%.
How does Franklin County compare with other Pennsylvania counties?
Franklin County ranks 6th highest of 67 counties by share of basement tests at or above 4.0 pCi/L, at 59%. Among its neighbors, Fulton County has the highest share at 70% and Adams County the lowest at 44%.
What bedrock is under Franklin County?
The largest mapped units are Martinsburg Formation (34% of the county), Rockdale Run Formation (7% of the county) and St. Paul Group (7% of the county), according to the USGS compilation of the Pennsylvania Geological Survey state map.