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Radon Levels in Henderson County, Illinois

Zone 1Highest predicted potential394 square miles · 6 bordering counties

What this means for you

  • Your area: EPA rates Henderson County Zone 1, the highest 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 3 radon tests reported to CDC for Henderson County (2015), 0.0% 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 2015, 0.0% of the radon tests reported to CDC for Henderson County, Illinois came back at or above the EPA action level of 4 pCi/L, and the median result was 3.4 pCi/L. EPA's Map of Radon Zones places the county in Zone 1, highest predicted potential. Radon levels vary from home to home, so only a test measures the level in yours.

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA predicts an average indoor of greater than 4 pCi/L (greater than 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: Low across 100% of the county's land area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Henderson County, 2015

Tests reported
3
At or above 4 pCi/L
0.0%
Median result
3.4 pCi/L
Reported results by concentration band, Henderson County, 2015
Under 2 pCi/L: 0%2 to 4 pCi/L: 100%4 pCi/L and above: 0%

Of 3 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.

Reported results by concentration band, Henderson County, 2015: data table
Result bandTests Calculated by Radon411Share Measured
Under 2 pCi/L00.0%
2 to 4 pCi/L3100.0%
4 pCi/L and above00.0%

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: 2015. Measured data period: 2005 to 2017 (every CDC figure on file).

Henderson County, In figures

Henderson County in figures

What the published data says about Henderson County, in words. A zone and a share of tests describe an area, never the level in any one home.

    • Predicted

      Predicted

      EPA places Henderson County in Zone 1, highest predicted potential, as it does 55 other counties of Illinois's 102.

      Of the 6 bordering counties, EPA places Des Moines County, Hancock County, Lee County, McDonough County, Mercer County and Warren County in Zone 1.

  • Reported tests

    Measured

    CDC has annual figures for Henderson County for 2 years, 2014 to 2015. In 2015, 0.0% of 3 reported tests were at or above 4 pCi/L.

  • Local record

    Illinois's radon program is the IEMA-OHS Radon Program, run by Illinois Emergency Management Agency and Office of Homeland Security; its contacts are under Local resources.

    The county's largest incorporated places are Oquawka, Dallas City and Stronghurst; the figures here cover them as part of the county.

Henderson County, Reported testing

Reported testing over time

Measured
Reported radon test results by year, Henderson 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
Reported radon test results by year, Henderson County, pCi/L: data table
YearMedian reported resultHighest reported resultShare of tests at or above 4 pCi/L
20146.8 pCi/L17.3 pCi/L66.7%
20153.4 pCi/L3.4 pCi/L0.0%

What these figures count

Every percentage here is a share of radon tests reported to CDC for Henderson County in 2015. It is not a share of homes in Henderson 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 (3 for 2015). CDC also reports the number of buildings tested (1), a different count, so the two totals are not interchangeable.

Henderson County, Comparison

How Henderson County compares

Measured

Henderson 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

2015, highest first. Each county’s own published CDC figure.

  1. Warren CountyIL27 tests66.7%
  2. Mercer CountyIL60 tests65.0%
  3. Hancock CountyIL6 tests50.0%
  4. McDonough CountyIL213 tests45.1%
  5. Henderson CountyThis page3 tests0.0%

Median reported result

Measured

2015, highest first. Each county’s own published CDC figure.

  1. Hancock CountyIL6 tests10.3 pCi/L
  2. Warren CountyIL27 tests5.4 pCi/L
  3. Mercer CountyIL60 tests5.1 pCi/L
  4. McDonough CountyIL213 tests3.8 pCi/L
  5. Henderson CountyThis page3 tests3.4 pCi/L

Each figure is that county’s own published CDC figure for 2015, counting radon tests reported to CDC, not homes. Henderson 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 2015: Des Moines County, IA; Lee County, IA. Every Illinois county’s own figure is in the Illinois county table.

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

Henderson County, Bordering counties

Counties bordering Henderson County

Calculated by Radon411

6 counties share a boundary with Henderson 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.

Henderson County, Local resources

Local resources in Illinois

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

IEMA-OHS Radon Program

Illinois Emergency Management Agency and Office of Homeland Security

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

Phone
(800) 325-1245
Licensing of radon professionals
The Agency also licenses and regulates the individuals who provide radon measurement and mitigation to the public.
Disclosure when a home is sold or rented
Illinois Radon Awareness Act - This is the legislation that requires the seller to provide to the buyer of any interest in residential real property the IEMA-OHS pamphlet entitled "Radon Testing Guidelines for Real Estate Transactions" and the Illinois Disclosure of Information on Radon Hazards.
Visit the program's page(opens in a new tab)

Test kits

Ask the program whether it has free or discounted kits, or compare kits you can buy.

Radon professionals

387 professionals are listed in Illinois.

Professionals in Illinois

Henderson County, Cities and towns

Cities and towns in Henderson County

The radon figures on this page are for Henderson County as a whole. They do not differ by city or town.

  • Oquawka
  • Dallas City (part)
  • Stronghurst
  • Lomax
  • Biggsville
  • Gladstone
  • Media
  • Raritan
  • Gulfport

9 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county.

Henderson County, Questions

Questions about radon in Henderson County

Common questions8 questions, answered from the figures above

Are radon levels high in Henderson County?

In 2015, 0.0% of the radon tests reported to CDC for Henderson County, Illinois were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.4 pCi/L. That is a share of reported tests, not of homes. EPA places Henderson County in Zone 1, highest predicted potential, a predicted average indoor screening level greater than 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 Illinois

How do I get a radon test in Henderson 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 Henderson County as a service area yet. The Illinois 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 stateIllinois radon program

Who does radon mitigation in Henderson County?

No listed mitigator names Henderson County as a service area yet; the Illinois directory lists 387 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 Illinois requires one.

How radon mitigation worksWhat mitigation costsMitigators in Illinois

What EPA radon zone is Henderson County in?

EPA places Henderson County, Illinois in Zone 1, which EPA describes as highest 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 Henderson 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 Henderson County?

Henderson 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 reported-test figures on this page describe Henderson County, Illinois in 2015. They describe tests other people carried out in other buildings, and none of them measures yours.

  • 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.

Henderson County, Products

Testing and mitigation products

Whatever the figures for Henderson County show, only a test tells you about one home.

Henderson 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.