Long-term kit
RL416 long-term radon test kit, lab fee included
- Lab fee included
Method: Alpha track
In home: 90 days to 12 months
Locations and reports
Radon Levels in Clarion County, Pennsylvania
EPA puts Clarion County in Zone 1, its highest radon zone, and 31.8% of its 107 reported radon tests (2020) were 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
Share at 4+ pCi/L
31.8%
1.5 pts above PA
- Clarion
- 31.8%
- PA
- 30.3%
107 tests, 2020
Median result
2.9pCi/L
Below action level
- Clarion
- 2.9 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2020
Tests reported
107
56th of 63 by tests
- Clarion
- 107
- Montgomery
- 10,508
Reported to CDC before any fix, 2020
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in PA
44 of 63
Middle half
- Clarion
- 31.8%
- Perry
- 57.7%
By share, of 63 with 30+ tests
Read a result for Clarion County
Starts at Clarion County's median, 2.9 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.9 pCi/L
Between 2 and 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 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. Clarion County's median reported result, 2020.
The data
Clarion County, At a glance
Clarion County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Clarion County in
USGS geologic potential: High across 98% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Clarion County, 2020
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 44.5% |
| 2015 | 52.0% |
| 2016 | 52.8% |
| 2017 | 40.6% |
| 2018 | 37.5% |
| 2019 | 36.1% |
| 2020 | 31.8% |
2020: 31.8%. Across these years the share ran from 31.8% to 52.8%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 107 tests reported to CDC for Clarion 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).
Clarion County, Compared
Clarion County radon figures, compared
Calculated by Radon411In Clarion County, about 3 in 10 reported tests in 2020 (34 of 107) were at or above EPA's action level. Against the national pool of 25.5%, the gap is 6.3 points higher. Across 67 Pennsylvania counties pooled together, 30.3% of tests reached that level, so Clarion County runs 1.5 points above its state.
Of 4 neighbours with a figure, all 4 reported a larger share at or above 4 pCi/L; the spread is 34.1% (Venango County) to 47.6% (Armstrong County). By share, Clarion County is 44th of 63 Pennsylvania counties with 30 or more tests for the same period.
Year by year, 2014 opened at 44.5% and 2020 closed at 31.8% (down 12.7 points), with 2016 the high at 52.8%. Half the tests came in under 2.9 pCi/L and half over it; the single highest reached 21.3 pCi/L. Below the action level, 33 tests (30.8%) came in under 2 pCi/L, against 44.3% statewide, and 40 tests (37.4%) fell between 2 and 4, against 25.4% statewide.
Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 31.8% share point the same way here. USGS geology rates 98% of the county's land high radon potential.
The busiest year on file was 2014, with 182 tests reported; the quietest, 2017, had 101.
Clarion CountyPennsylvania, pooled
| Year | Tests | Clarion County, at or above 4 pCi/L | Pennsylvania, pooled |
|---|---|---|---|
| 2014 | 182 | 44.5% | 36.1% |
| 2015 | 179 | 52.0% | 37.8% |
| 2016 | 161 | 52.8% | 34.4% |
| 2017 | 101 | 40.6% | 35.1% |
| 2018 | 104 | 37.5% | 30.5% |
| 2019 | 155 | 36.1% | 31.4% |
| 2020 | 107 | 31.8% | 30.3% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Clarion County, State data
Pennsylvania's own radon test data
MeasuredWhat Pennsylvania's own agencies publish about radon tests in Clarion 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 Clarion County
Pennsylvania DEP publishes its figures by ZIP code, not by county. These are the 32 ZIP codes that lie wholly or partly in Clarion County, each with the state's own figures for it. Period: Period not stated by DEP.
| ZIP code | What the state reports |
|---|---|
| 15829 | Basement: average 9.2 pCi/L, 46 tests; First floor: figures not shown |
| 15860 | Basement: figures not shown; First floor: figures not shown |
| 15864 | Basement: average 9.8 pCi/L, 50 tests; First floor: figures not shown |
| 16028 | Basement: average 13.7 pCi/L, 50 tests |
| 16036 | Basement: figures not shown; First floor: figures not shown |
| 16049 | Basement: average 14.4 pCi/L, 79 tests; First floor: figures not shown |
| 16054 | Basement: figures not shown |
| 16213 | Basement: figures not shown |
| 16214 | Basement: average 8.5 pCi/L, 814 tests; First floor: average 3.0 pCi/L, 165 tests |
| 16217 | Basement: figures not shown; First floor: figures not shown |
| 16220 | Basement: figures not shown; First floor: figures not shown |
| 16224 | Basement: average 10.1 pCi/L, 51 tests; First floor: figures not shown |
| 16230 | Basement: figures not shown |
| 16232 | Basement: average 7.6 pCi/L, 136 tests; First floor: figures not shown |
| 16233 | Basement: average 8.0 pCi/L, 90 tests; First floor: figures not shown |
| 16235 | Basement: average 12.5 pCi/L, 110 tests; First floor: figures not shown |
| 16240 | Basement: figures not shown; First floor: figures not shown |
| 16242 | Basement: average 9.8 pCi/L, 179 tests; First floor: figures not shown |
| 16248 | Basement: average 9.6 pCi/L, 85 tests; First floor: figures not shown |
| 16254 | Basement: average 7.4 pCi/L, 270 tests; First floor: average 2.9 pCi/L, 33 tests |
| 16255 | Basement: average 6.6 pCi/L, 59 tests; First floor: figures not shown |
| 16258 | Basement: average 6.3 pCi/L, 74 tests; First floor: figures not shown |
| 16260 | Basement: figures not shown; First floor: figures not shown |
| 16319 | Basement: average 9.6 pCi/L, 85 tests; First floor: figures not shown |
| 16326 | Basement: figures not shown; First floor: figures not shown |
| 16331 | Basement: figures not shown; First floor: figures not shown |
| 16332 | Basement: figures not shown; First floor: figures not shown |
| 16334 | Basement: figures not shown; First floor: figures not shown |
| 16353 | Basement: average 15.8 pCi/L, 98 tests; First floor: figures not shown |
| 16361 | Basement: figures not shown; First floor: figures not shown |
| 16364 | Basement: average 13.2 pCi/L, 40 tests; First floor: figures not shown |
| 16373 | Basement: average 27.0 pCi/L, 155 tests; First floor: average 11.8 pCi/L, 46 tests |
- 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.
Clarion County, Geology
The ground under Clarion County
PredictedMost of the ground under Clarion County is one class on USGS's geologic map: 98.0% of its land is high radon potential, with 2.0% moderate. 98.0% of it lies in the area the map calls Pennsylvanian Rocks of the Pittsburgh Low Plateau, to which USGS gives a radon index of 14, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Pennsylvanian Rocks of the Pittsburgh Low Plateau | Pennsylvanian marine shale, siltstone, sandstone, limestone, and coal. | High | 14 | 98.0% |
| High Plateau | Marine and continental Devonian-Pennsylvanian shale, sandstone, limestone, siltstone, and coal. | Moderate | 10 | 2.0% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Clarion County beside the ground around it
Clarion County has more high-potential ground than Pennsylvania as a whole: 98.0% of its land against 70.4%. Of the 5 counties that border it, 1 has more high-potential ground, Armstrong County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Clarion County, Local resources
Radon testing and mitigation in Clarion County
- Radon DivisionRadon Division, run by Department of Environmental Protection, licenses or certifies radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in Pennsylvania.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
Through an EPA-funded program, hospitals give parents of newborn children a packet of information which includes a coupon for a free radon test kit from the DEP.
- Compare kits
- Professionals in Pennsylvania151 professionals are listed in Pennsylvania.
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
Clarion County, Questions
Questions about radon in Clarion County
Are radon levels high in Clarion County?
In 2020, 31.8% of the radon tests reported to CDC for Clarion County, Pennsylvania were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.9 pCi/L. Of 63 Pennsylvania counties with 30 or more tests for the same period, 43 reported a higher share; pooled, the state comes to 30.3%.
Which counties border Clarion County?
Clarion County borders 5 counties: Venango County, Jefferson County, Armstrong County, Forest County and Butler County.
Products
Clarion County, Products
Testing a home in Clarion County
In Clarion County, 31.8% of 107 tests reported to CDC in 2020 reached 4 pCi/L, against 30.3% pooled across Pennsylvania. In Zone 1 the year-round level in Clarion 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
MonitorKidde
Radon Detector (RAB) battery digital radon detector with an alarm
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
First reading: Within 12 hours
Short-term kit
Air Chek Short-Term radon test kit you hang, lab fee included
- Lab fee included
In home: 72 to 168 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Clarion County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Clarion County
Explore
Clarion County, Bordering counties
Counties bordering Clarion County
Calculated by Radon411- Radon levels in Forest CountyEPA zone 2
56.3%at or above 4 pCi/L
Median 5.0 pCi/L · 16 tests · 24.5 points above Clarion County
- Radon levels in Armstrong CountyEPA zone 1
47.6%at or above 4 pCi/L
Median 3.7 pCi/L · 187 tests · 15.8 points above Clarion County
- Radon levels in Butler CountyEPA zone 1
42.3%at or above 4 pCi/L
Median 3.3 pCi/L · 1,492 tests · 10.5 points above Clarion County
- Radon levels in Jefferson CountyEPA zone 2
38.6%at or above 4 pCi/L
Median 2.6 pCi/L · 254 tests · 6.8 points above Clarion County
- Radon levels in Venango CountyEPA zone 1
34.1%at or above 4 pCi/L
Median 3.0 pCi/L · 179 tests · 2.3 points above Clarion County
Clarion County, Cities and towns
Cities and towns in Clarion County
About 36,680 people live in Clarion County by the Census Bureau's estimate for July 1, 2025, 520 fewer than in 2020 (−1.4%). That works out to 61 people per square mile of land. No town dominates: Clarion, the largest, has 4,037 residents, 11.0% of the total. Reported testing is thin here: 107 tests over 2020, or 2.9 for every 1,000 residents (2025 estimate), where Pennsylvania as a whole comes to 7.2.
From Clarion to Callensburg, CDC publishes no figure by town: each reads Clarion County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Clarion | 4,037 | +2.9% | 11.0% |
| Knox | 1,068 | −2.6% | 2.9% |
| New Bethlehem | 943 | −2.7% | 2.6% |
| Rimersburg | 919 | −3.0% | 2.5% |
| East Brady | 799 | −2.3% | 2.2% |
| Sligo | 666 | −1.8% | 1.8% |
| Emlentonextends beyond Clarion County | 600 | −2.6% | Counted whole |
| Strattanville | 521 | −2.1% | 1.4% |
| Hawthorn | 468 | −1.9% | 1.3% |
| Shippenville | 440 | −0.5% | 1.2% |
| St. Petersburg | 326 | −3.3% | 0.9% |
| Foxburg | 178 | −1.7% | 0.5% |
- Callensburg
13 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Clarion County is counted whole, so it has no share.
Clarion County, Homes
Homes in Clarion County
Clarion County is a place of houses on their own lots: 76% of its 18,878 homes are detached single-family houses, against 57% across Pennsylvania. Half of its homes were built before 1966, close to Pennsylvania's 1965: 43% date from before 1960 and 11% from 2000 or later. 71% 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 | Clarion County | Pennsylvania |
|---|---|---|
| Housing units | 18,878 | 5,779,663 |
| Detached houses | 76% | 57% |
| In buildings of 5 or more | 8% | 13% |
| Mobile homes | 11% | 4% |
| Built before 1960 | 43% | 45% |
| Built since 2000 | 11% | 14% |
| Middle year built | 1966 | 1965 |
| Owner-occupied | 71% | 69% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.