Radon Testing & Mitigation in Clearfield County, PA
53% of 10,770 basement radon tests reported to PA DEP in Clearfield County measured 4.0 pCi/L or higher, EPA's action level (median 4.3 pCi/L).
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Radon in Clearfield County: 53% of the 10,770 basement tests reported to PA DEP measured 4.0 pCi/L or higher, EPA's action level, 16 points above the 37% statewide share. The county ranks 16th highest of 67, and the median result is 4.3 pCi/L. Only a test shows one home's level.
Radon Test Results by ZIP Code in Clearfield County
24 ZIP codes in Clearfield 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 16838 (Grampian): 63% of 158 tests. The lowest is in 16666 (Osceola Mills): 40% of 139 tests.
| ZIP code | Post office | Basement tests | Median pCi/L | At or above 4.0 |
|---|---|---|---|---|
| 15801 | Du Bois | 7,207 | 4.5 | 54% |
| 16830 | Clearfield | 1,390 | 3.5 | 46% |
| 16833 | Curwensville | 296 | 5.1 | 60% |
| 16858 | Morrisdale | 219 | 6.0 | 60% |
| 16651 | Houtzdale | 206 | 5.1 | 58% |
| 16838 | Grampian | 158 | 5.5 | 63% |
| 16866 | Philipsburg (part) | 150 | 3.0 | 42% |
| 16666 | Osceola Mills | 139 | 3.2 | 40% |
| 15856 | Rockton | 102 | 4.1 | 52% |
| 15849 | Penfield | 84 | 4.6 | 57% |
| 16881 | Woodland | 84 | 5.6 | 55% |
| 16878 | West Decatur | 81 | 3.6 | 46% |
| 15848 | Luthersburg | 56 | 3.8 | 50% |
| 16627 | Coalport | 51 | 2.9 | 37% |
| 15757 | Mahaffey | 50 | 4.9 | 58% |
Show all 24 ZIP codes
| 16836 | Frenchville | 49 | 5.6 | 61% |
| 16671 | Ramey | 42 | 6.3 | 57% |
| 16661 | Madera | 38 | 1.9 | 16% |
| 16680 | Smithmill | 34 | 5.0 | 56% |
| 16863 | Olanta | 33 | 4.8 | 52% |
| 16692 | Westover | 31 | 7.0 | 71% |
| 16849 | Lanse | 26 | 4.7 | 58% |
| 16845 | Karthaus (part) | 25 | 5.7 | 72% |
| 16839 | Grassflat | 23 | 3.1 | 44% |
| Clearfield County | 10,770 | 4.3 | 53% | |
| Pennsylvania | 2,629,492 | 2.8 | 37% | |
See your ZIP in the table?
Get matched with a DEP-certified radon professionalFirst-floor tests in Clearfield County: 957 on record, median 1.8 pCi/L, 28% at or above 4.0 pCi/L.
EPA's Map of Radon Zones (1993) places Clearfield 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 Clearfield County
65% of Clearfield County's 38,198 housing units were built before 1980, in line with the 67% statewide figure; 26% 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 Clearfield County
Allegheny Formation (Pennsylvanian; sandstone) underlies 43% of the county. Pottsville Formation (Pennsylvanian; sandstone and conglomerate) underlies 24% of the county.
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 Clearfield County
Lenders reported 630 home-purchase mortgages originated in Clearfield 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 Clearfield County
Clearfield County has 50 municipalities: 1 city, 19 boroughs and 30 townships.
Show all 50 municipalities
Beccaria township, Bell township, Bigler township, Bloom township, Boggs township, Bradford township, Brady township, Brisbin borough, Burnside borough, Burnside township, Chest township, Chester Hill borough, Clearfield borough, Coalport borough, Cooper township, Covington township, Curwensville borough, Decatur township, DuBois city, Falls Creek borough, Ferguson township, Girard township, Glen Hope borough, Goshen township, Graham township, Grampian borough, Greenwood township, Gulich township, Houtzdale borough, Huston township, Irvona borough, Jordan township, Karthaus township, Knox township, Lawrence township, Mahaffey borough, Morris township, New Washington borough, Newburg borough, Osceola Mills borough, Penn township, Pike township, Pine township, Ramey borough, Sandy township, Troutville borough, Union township, Wallaceton borough, Westover borough, Woodward township.
Source: U.S. Census Bureau, 2025 Gazetteer Files, county subdivisions. Retrieved September 29, 2026.
City Pages in Clearfield County
Neighboring Counties
- Radon in Blair County → 43% of 17,286 basement tests at or above 4.0 pCi/L
- Radon in Cambria County → 44% of 16,280 basement tests at or above 4.0 pCi/L
- Radon in Cameron County → 49% of 437 basement tests at or above 4.0 pCi/L
- Radon in Centre County → 56% of 39,672 basement tests at or above 4.0 pCi/L
- Radon in Clinton County → 46% of 4,689 basement tests at or above 4.0 pCi/L
- Radon in Elk County → 48% of 3,490 basement tests at or above 4.0 pCi/L
- Radon in Indiana County → 46% of 9,096 basement tests at or above 4.0 pCi/L
- Radon in Jefferson County → 56% of 4,552 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 Clearfield 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 Clearfield 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 Clearfield County typically costs $850–$2,150. 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 Clearfield County are at or above the EPA action level?
53% of the 10,770 basement tests reported to PA DEP from Clearfield County measured 4.0 pCi/L or higher, against 37% statewide. The median result is 4.3 pCi/L, and 11% of tests measured 20 pCi/L or higher.
Which Clearfield County ZIP code has the highest radon test results?
Among ZIP codes with at least 100 basement tests, 16838 (Grampian) has the highest share at or above 4.0 pCi/L: 63% of 158 tests, with a median of 5.5 pCi/L. 16666 (Osceola Mills) has the lowest, at 40%.
How does Clearfield County compare with other Pennsylvania counties?
Clearfield County ranks 16th highest of 67 counties by share of basement tests at or above 4.0 pCi/L, at 53%. Among its neighbors, Centre County has the highest share at 56% and Blair County the lowest at 43%.
What bedrock is under Clearfield County?
The largest mapped units are Allegheny Formation (43% of the county) and Pottsville Formation (24% of the county), according to the USGS compilation of the Pennsylvania Geological Survey state map.