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Radon Levels in Lewis County, Missouri

Zone 2Moderate predicted potential513 square miles · 6 bordering counties

What this means for you

  • Your area: EPA rates Lewis County Zone 2, the middle 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: 1 buildings with radon tests reported to CDC for Lewis County (2023). CDC publishes no share above the action level here.
  • 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 2023, the median radon test reported to CDC for Lewis County, Missouri was 3.7 pCi/L. EPA's Map of Radon Zones places the county in Zone 2, moderate predicted potential. Radon levels vary from home to home, so only a test measures the level in yours.

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

EPA predicts an average indoor of 2 to 4 pCi/L (75 to 150 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: Moderate across 91% of the county's land area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Lewis County, 2023

Buildings tested
1
At or above 4 pCi/L
Not available
Median result
3.7 pCi/L

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: 2023. Measured data period: 2005 to 2023 (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

      Predicted

      EPA places Lewis County in Zone 2, moderate predicted potential, as it does 96 other counties of Missouri's 115.

      Of the 6 bordering counties, EPA places Adams County and Hancock County in Zone 1 and Clark County, Knox County, Marion County and Shelby County in Zone 2.

  • Reported tests

    Measured

    CDC has annual figures for Lewis County for 7 years, 2014 to 2022. In 2022, 0.0% of 1 reported tests were at or above 4 pCi/L.

    Across those years the share ranged from 0.0% (2022) to 100.0% (2014). Few tests in a year can move it a long way.

  • Local record

    Missouri's radon program is the Missouri Radon Program, run by Missouri Department of Health and Senior Services; its contacts are under Local resources.

    The county's largest incorporated places are Canton, La Grange and La Belle; the figures here cover them as part of the county.

Lewis County, Reported testing

Reported testing over time

Measured
Reported radon test results by year, Lewis County, pCi/LLogarithmic scale: each step up the axis multiplies the level, so the median and the single highest result can share one chart. The darker gridline is EPA's action level, 4 pCi/L.
Median reported resultHighest reported result

No figures are published for 2019 to 2020. The axis keeps the space for the missing years and the line is not drawn across it.

Reported radon test results by year, Lewis County, pCi/L: data table
YearMedian reported resultHighest reported resultShare of tests at or above 4 pCi/L
20147.7 pCi/L11.3 pCi/L100.0%
20152.1 pCi/L11.2 pCi/L25.0%
20162.6 pCi/L2.6 pCi/L0.0%
20171.4 pCi/L4.8 pCi/L25.0%
20181.4 pCi/L3.4 pCi/L0.0%
20211.8 pCi/L1.8 pCi/L0.0%
20221.2 pCi/L1.2 pCi/L0.0%
20233.7 pCi/L3.7 pCi/LNo data

What these figures count

Every percentage here is a share of radon tests reported to CDC for Lewis County in 2023. 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. CDC also reports the number of buildings tested (1), a different count, so the two totals are not interchangeable.

Lewis County, Comparison

How Lewis County compares

Measured

Lewis 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

Measured

2023, highest first. Each county’s own published CDC figure.

Lewis County has no published figure for this measure in 2023, so it is not ranked here.

Median reported result

Measured

2023, highest first. Each county’s own published CDC figure.

  1. Marion CountyMOTest count not published6.3 pCi/L
  2. Lewis CountyThis pageTest count not published3.7 pCi/L
  3. Knox CountyMOTest count not published1.4 pCi/L
  4. Shelby CountyMOTest count not published0.8 pCi/L
  5. Clark CountyMOTest count not published0.6 pCi/L

Each figure is that county’s own published CDC figure for 2023, 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. No published CDC figure for 2023: Adams County, IL; Hancock County, IL. Every Missouri county’s own figure is in the Missouri county table.

CDC publishes this figure only for counties here, so there is no state or national number to compare Lewis County, Missouri with.

Lewis County, Bordering counties

Counties bordering Lewis County

Calculated by Radon411

6 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.

Lewis County, Local resources

Local resources in Missouri

Who to ask in Missouri: the state's radon program, test kits and professionals.

Missouri Radon Program

Missouri Department of Health and Senior Services

Missouri’s radon program answers questions about testing, mitigation and the rules where you live.

Phone
573-751-6102
Email
radon@health.mo.gov
Visit the program's page(opens in a new tab)

Test kits

The program says: Free radon test kits are available for Missouri residents (limit one per household).

Radon professionals

6 professionals are listed in Missouri.

Professionals in Missouri

Lewis 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.

  • Canton
  • La Grange
  • La Belle
  • Lewistown
  • Ewing
  • Monticello

6 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?

No CDC testing statistics are published here for Lewis County, Missouri yet. EPA places Lewis County in Zone 2, moderate predicted potential, a predicted average indoor screening level 2 to 4 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.

What a radon level meansRadon in Missouri

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 Missouri 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 stateMissouri radon program

Who does radon mitigation in Lewis County?

No listed mitigator names Lewis County as a service area yet; the Missouri directory lists 6 companies. 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 Missouri requires one.

How radon mitigation worksWhat mitigation costsMitigators in Missouri

What EPA radon zone is Lewis County in?

EPA places Lewis County, Missouri in Zone 2, which EPA describes as moderate 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 6 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 EPA zone on this page describes Lewis County as a whole. It is a prediction for an area, and it does not measure your building.

  • 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.

    How to test a home
  • If you are buying

    Ask for past results and any system's post-mitigation test, and test during the sale.

    Buying a house: radon guide
  • If you are selling

    Testing before you list puts the timing in your hands; disclosure rules differ by state.

    Selling a house: radon guide
  • 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.

    Radon in rental homes

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.

Lewis County / Next steps

What to do next

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.