Locations and reports
Radon Levels in Lewis County, Washington
What this means for you
- Your area: EPA rates Lewis County Zone 3, the lowest of its three radon zones. That is a prediction for the whole county, and homes with elevated levels occur in all three zones.
- Local tests: Of 10 radon tests reported to CDC for Lewis County (2020), 70.0% were at or above 4 pCi/L, EPA's action level.
- Your home: The only way to know your home’s level is to test it.
pCi/L (picocuries per liter) is the unit radon is measured in. EPA recommends fixing a home at 4 pCi/L or above, its action level.
In 2020, 70.0% of the radon tests reported to CDC for Lewis County, Washington came back at or above the EPA action level of 4 pCi/L, and the median result was 15.6 pCi/L. EPA's Map of Radon Zones places the county in Zone 3, lower predicted potential. Radon levels vary from home to home, so only a test measures the level in yours.
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
EPA predicts an average indoor of less than 2 pCi/L (less than 75 Bq/m³) across the county as a whole.
This is a county-level geologic prediction. It is not a measurement of any address, and houses with elevated radon are found in all three zones.
USGS geologic potential: High across 100% of the county's land area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Lewis County, 2020
- Tests reported
- 10
- At or above 4 pCi/L
- 70.0%
- Median result
- 15.6 pCi/L
Of 10 pre-mitigation tests reported to CDC, not homes in this area. CDC publishes the share in each band, not a count per band, so the per-band counts in the table are calculated by Radon411 and rounded to add up to the published total.
| Result band | Tests Calculated by Radon411 | Share Measured |
|---|---|---|
| Under 2 pCi/L | 3 | 30.0% |
| 2 to 4 pCi/L | 0 | 0.0% |
| 4 pCi/L and above | 7 | 70.0% |
Distribution of tested buildings, not this house. People testing before a sale, or because they suspect a problem, are over-represented in any reported testing data.
Measured: CDC tracking data. Figure above: 2020. Measured data period: 2005 to 2020 (every CDC figure on file).
Lewis County, In figures
Lewis County in figures
What the published data says about Lewis County, in words. A zone and a share of tests describe an area, never the level in any one home.
Predicted
PredictedEPA places Lewis County in Zone 3, lower predicted potential, as it does 17 other counties of Washington's 39.
Of the 8 bordering counties, EPA places Skamania County in Zone 1, Yakima County in Zone 2 and Cowlitz County, Grays Harbor County, Pacific County, Pierce County, Thurston County and Wahkiakum County in Zone 3.
Reported tests
MeasuredCDC has annual figures for Lewis County for 7 years, 2014 to 2020. In 2020, 70.0% of 10 reported tests were at or above 4 pCi/L.
Across those years the share ranged from 0.0% (2017) to 70.0% (2020). Few tests in a year can move it a long way.
Local record
Washington's radon program is the Radon Program, run by Washington State Department of Health; its contacts are under Local resources.
The county's largest incorporated places are Centralia, Chehalis and Winlock; the figures here cover them as part of the county.
Lewis County, Reported testing
Reported testing over time
Measured| Year | Median reported result | Highest reported result | Share of tests at or above 4 pCi/L |
|---|---|---|---|
| 2014 | 0.4 pCi/L | 10.8 pCi/L | 2.8% |
| 2015 | 0.1 pCi/L | 8.0 pCi/L | 27.3% |
| 2016 | 0.8 pCi/L | 3.9 pCi/L | 0.0% |
| 2017 | 1.8 pCi/L | 3.5 pCi/L | 0.0% |
| 2018 | 2.4 pCi/L | 4.0 pCi/L | 11.1% |
| 2019 | 0.4 pCi/L | 17.9 pCi/L | 20.0% |
| 2020 | 15.6 pCi/L | 22.0 pCi/L | 70.0% |
What these figures count
Every percentage here is a share of radon tests reported to CDC for Lewis County in 2020. It is not a share of homes in Lewis County, and it is not a random sample: it counts only the tests people chose to run and that were reported.
The shares and the median are calculated from pre-mitigation tests (10 for 2020). CDC also reports the number of buildings tested (7), a different count, so the two totals are not interchangeable.
Lewis County, Comparison
How Lewis County compares
MeasuredLewis County's own published CDC figures beside those of the counties that border it, for the same period.
Share of reported tests at or above 4 pCi/L
Measured2020, highest first. Each county’s own published CDC figure.
- Lewis CountyThis page10 tests70.0%
- Skamania CountyWA17 tests52.9%
- Thurston CountyWA46 tests6.5%
- Yakima CountyWA57 tests5.3%
- Pierce CountyWA420 tests4.3%
- Cowlitz CountyWA24 tests4.2%
- Grays Harbor CountyWA9 tests0.0%
- Pacific CountyWA3 tests0.0%
- Wahkiakum CountyWA1 test0.0%
Median reported result
Measured2020, highest first. Each county’s own published CDC figure.
- Lewis CountyThis page10 tests15.6 pCi/L
- Skamania CountyWA17 tests4.9 pCi/L
- Grays Harbor CountyWA9 tests1.3 pCi/L
- Cowlitz CountyWA24 tests1.1 pCi/L
- Pierce CountyWA420 tests0.7 pCi/L
- Yakima CountyWA57 tests0.7 pCi/L
- Thurston CountyWA46 tests0.4 pCi/L
- Pacific CountyWA3 tests0.2 pCi/L
- Wahkiakum CountyWA1 test0.1 pCi/L
Each figure is that county’s own published CDC figure for 2020, counting radon tests reported to CDC, not homes. Lewis County is this page. Nothing is averaged or combined across counties. The test count beside each county is CDC’s published number of pre-mitigation tests behind its figures. Figures from few tests can swing widely from year to year. Every Washington county’s own figure is in the Washington county table.
CDC publishes this figure only for counties here, so there is no state or national number to compare Lewis County, Washington with.
Lewis County, Bordering counties
Counties bordering Lewis County
Calculated by Radon4118 counties share a boundary with Lewis County, computed from Census county geometry. Radon potential follows geology rather than county lines, so a bordering county’s report can be worth reading alongside this one.
- Cowlitz CountyWAZone 3: Lower predicted potential
- Pierce CountyWAZone 3: Lower predicted potential
- Thurston CountyWAZone 3: Lower predicted potential
- Skamania CountyWAZone 1: Highest predicted potential
- Wahkiakum CountyWAZone 3: Lower predicted potential
- Pacific CountyWAZone 3: Lower predicted potential
- Grays Harbor CountyWAZone 3: Lower predicted potential
- Yakima CountyWAZone 2: Moderate predicted potential
Lewis County, Local resources
Local resources in Washington
Who to ask in Washington: the state's radon program, test kits and professionals.
Radon Program
Washington State Department of Health
Washington’s radon program answers questions about testing, mitigation and the rules where you live.
- Phone
- 360-236-3200
- doh.radon@doh.wa.gov
Test kits
The program says: We have a limited supply of free radon test kits.
Radon professionals
No professionals are listed in Washington yet. The state program can point you to registered testers and mitigators.
See the Washington directoryLewis County, Cities and towns
Cities and towns in Lewis County
The radon figures on this page are for Lewis County as a whole. They do not differ by city or town.
- Centralia
- Chehalis
- Winlock
- Napavine
- Morton
- Mossyrock
- Toledo
- Vader
- Pe Ell
9 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files.
Lewis County, Questions
Questions about radon in Lewis County
Common questions8 questions, answered from the figures above
Are radon levels high in Lewis County?
In 2020, 70.0% of the radon tests reported to CDC for Lewis County, Washington were at or above 4 pCi/L, and the median reported pre-mitigation result was 15.6 pCi/L. That is a share of reported tests, not of homes. EPA places Lewis County in Zone 3, lower predicted potential, a predicted average indoor screening level less than 2 pCi/L. Homes with elevated levels occur in all three zones, so the figures describe the area, not your house. Testing is the only way to know the radon level in a specific building.
How do I get a radon test in Lewis County?
EPA says you can test your home yourself or hire a qualified radon test company, and that either approach takes only a small amount of time and effort. No certified tester listed on Radon411 names Lewis County as a service area yet. The Washington radon program is the place to ask about certified testers and any test kit offer it runs.
How to test a homeTest kits comparedFree and low-cost kits by stateWashington radon program
Who does radon mitigation in Lewis County?
Radon411 has no certified mitigators listed for Washington yet. EPA recommends having a qualified contractor fix a home with a radon problem, because lowering high radon levels takes technical knowledge and special skills, and some states require the work to be done by a licensed or certified professional. Your state radon program is the place to check whether Washington requires one.
How radon mitigation worksWhat mitigation costsWashington radon program
What EPA radon zone is Lewis County in?
EPA places Lewis County, Washington in Zone 3, which EPA describes as lower predicted potential for the area. A zone is a prediction for the whole county and never determines whether a particular home should be tested. EPA recommends testing every home regardless of zone.
Should I test my home in Lewis County?
Yes. Testing is the only way to know the radon level in a specific building. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. How to test a home.
When is the best time of year to test?
EPA says short-term tests stay in the home from 2 to 90 days and that all radon tests should run a minimum of 48 hours; long-term tests stay more than 90 days. EPA's guides do not name a best season: they say radon levels tend to vary from day to day and season to season, so a long-term test is more likely than a short-term test to tell you the year-round average.
What does it cost to test?
EPA's Citizen's Guide calls testing easy and inexpensive, and EPA's Home Buyer's and Seller's Guide says passive short-term and long-term devices are generally inexpensive, while active devices may cost more. No national average price is published for this, so Radon411 does not give one. What testing costs.
Which counties border Lewis County?
Lewis County borders 8 counties, derived from Census county geometry. Radon potential follows geology rather than county lines, so a bordering county's report can be relevant.
What these figures mean if you own, buy, sell or rent
The reported-test figures on this page describe Lewis County, Washington in 2020. They describe tests other people carried out in other buildings, and none of them measures yours.
- How to test a home
If you own your home
Test the lowest lived-in level; a short-term kit screens in days, a long-term kit reflects the year.
- Buying a house: radon guide
If you are buying
Ask for past results and any system's post-mitigation test, and test during the sale.
- Selling a house: radon guide
If you are selling
Testing before you list puts the timing in your hands; disclosure rules differ by state.
- Radon in rental homes
If you rent, or rent out a home
A tenant can test; a fix is the owner's to make, and duties differ by state.
How long a test has to run, under what conditions, and what EPA says a result means: the testing standard, in full.
Lewis County, Products
Testing and mitigation products
Whatever the figures for Lewis County show, only a test tells you about one home.
Testing
- Short-term test kitsPassive detectors exposed for a few days under closed-building conditions, then analyzed by a lab.
- Long-term test kitsDetectors exposed for more than 90 days, for a closer picture of the annual average.
- Continuous monitorsPowered devices that log radon on a repeating cycle, often used for transaction tests.
- Digital detectorsConsumer devices that display a running radon reading without a lab.
- Water radon testsKits for radon dissolved in well water, analyzed by a lab.
Mitigation
- Mitigation fansThe inline fan that keeps a soil depressurization system running, sized by the installer.
- System indicatorsU-tube manometers and fan alarms that show whether a mitigation system is still working.
- Sealing materialsCrack, joint and sump sealing used alongside a mitigation system, not instead of one.
Lewis County / Next steps
What to do next
Learn
Know what radon is
What radon is, how it gets indoors, and why a county zone is not a reading for your home.
Learn about radonTest
Test the building you live in
Short-term or long-term, where the device goes, and closed-house conditions.
How to testFix
Bring a high level down
How a mitigation system works, and the retest that confirms it.
How mitigation worksFind a pro
Hire a certified professional
Measurement and mitigation professionals by state, with their certifications.
Find a professional
Informational. Follow EPA guidance. EPA says all radon tests should be taken for a minimum of 48 hours, with windows and doors closed from 12 hours before a short-term test.