Radon levels in Clearwater County, Idaho
LowEPA Zone 1Predicted long-term basement average of 1.8 pCi/L (model estimate) across 5 ZIP codes - close to the US average of 1.8, about 31% below the Idaho average of 2.6. Ranked #44 of 44 Idaho counties.
Test Clearwater County, ID once anyway - radon varies house to house
The predicted basement average here is 1.8 pCi/L, below the EPA's 2 pCi/L "consider fixing" threshold. That's good news for the area - but the EPA still recommends every home be tested, because foundation cracks, soil pockets and ventilation make one house very different from its neighbor. One inexpensive kit settles it.
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Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. Measured state test results are shown separately below, labeled with their source and years. How the numbers work.
1.8 ± 0.07
pCi/L predicted basement mean (model SD)
1.3 ± 0.12
pCi/L predicted upstairs (above-ground) mean
1.6-3.2
range of ZIP-level basement predictions in the county
Measured radon tests in Clearwater County (Idaho Department of Health and Welfare, through 2019)
Actual results from home radon tests reported to the state, separate from the model estimate above. Coverage: through 2019 (start year not stated by the source).
- Measured mean
- 2.9 pCi/L
- Results ≥ 4 pCi/L
- 31.6%
- Sample
- 171 tests
| Figure | Model (predicted) | State tests (measured) |
|---|---|---|
| Mean, pCi/L | 1.8 basement | 2.9 |
| Share ≥ 4 pCi/L | not a model output | 31.6% |
The measured mean runs 1.1 pCi/L above the model because state test data is voluntary and skews toward basements, winter, and homeowners who already suspected a problem, while the model estimates the long-term average across all homes.
Source: Home Radon Test Results by Zip Code, Idaho Department of Health and Welfare, Indoor Environment / Radon Program. No license statement on the public feature service (publicly shared by the IDHW environmental-health account). Method and download.
Tested above 4 pCi/L? Get a mitigation quote from a certified local contractor
Typical mitigation runs $800-$2,500 and takes a day. Installers guarantee the system brings levels under 4 pCi/L. Tell us where you are in Clearwater County, ID and a certified mitigator will follow up - no obligation.
What this means for Clearwater
The typical Clearwater County home is predicted below 2 pCi/L, the lowest band. That is the best case an area can show - but it describes the average house, and the ZIP-level predictions within the county still span 1.6 to 3.2 pCi/L.
Note that the EPA classifies Clearwater County as Zone 1 while the newer model predicts 1.8 pCi/L. The zone map predates two decades of test data; where they disagree, we grade on the model but show both. County figures weight each ZIP by its 2010 Census population, so they describe where people live rather than empty land.
Comparable Idaho counties: Canyon County (1.9), Nez Perce County (2.0), Washington County (2.1), Idaho County (2.1). The state's highest is Teton County at 4.4 pCi/L.
ZIP codes in Clearwater County
Predicted basement and upstairs means by ZIP (model estimate). ZIPs whose land is mostly in this county.
If your test comes back at 4 pCi/L or higher
Mitigation is a routine job: a fan-driven pipe that vents soil gas from under the slab to above the roofline, typically $800-$2,500 installed (typical range; local quotes vary). Use certified professionals: EPA find-a-professional. Read the full mitigation guide.
Clearwater County radon questions
- Is radon high in Clearwater County, Idaho?
- Low. The model predicts a long-term basement average of 1.8 pCi/L in Clearwater County (close to the US average of 1.8 and about 31% below the Idaho average of 2.6). That is below the EPA's 2 pCi/L "consider fixing" threshold, though individual homes still vary. Ranked 44 of 44 Idaho counties.
- What do actual radon tests show in Clearwater County?
- Idaho Department of Health and Welfare data covering through 2019 (171 tests) shows an average of 2.9 pCi/L, 31.6% of results at or above the 4 pCi/L action level. These are voluntary home tests, so they skew toward basements and toward homes where radon was suspected; the model's predicted long-term basement average for the county is 1.8 pCi/L.
- Should I test for radon in Clearwater County?
- Yes, once. The EPA recommends testing every home regardless of area, and the model's ZIP-level predictions in Clearwater County already range from 1.6 to 3.2 pCi/L. A short-term kit costs little and settles the question for your house.
- What does EPA Radon Zone 1 mean for Clearwater County?
- Zone 1 - highest potential (predicted average > 4 pCi/L). The zone map dates from 1993 and classifies whole counties. The newer model's predicted average of 1.8 pCi/L does not line up with Zone 1, which is common - the EPA itself says high-radon homes exist in every zone. Neither replaces a test of your own home.
- How much does radon mitigation cost in Clearwater County?
- A standard active sub-slab depressurization system typically runs $800-$2,500 installed nationally; Idaho quotes vary with foundation type (slab, crawlspace, basement), home size and local labor. Get two or three bids from certified mitigators listed by your state radon program or the EPA's find-a-professional page.
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