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Radon Levels in Hamilton County, Illinois

EPA puts Hamilton County in Zone 2, its middle radon zone, and only 6 radon tests from it are on file with CDC (2015). Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

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  • Share at 4+ pCi/L

    22.6%

    21.7 pts below IL

    Hamilton
    22.6%
    Illinois
    44.3%

    31 tests, 2006 to 2015

  • Median result

    2.0pCi/L

    Below action level

    Hamilton
    2.0 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2006 to 2015

  • Tests reported

    31

    92nd of 92 by tests

    Hamilton
    31
    Cook
    12,801

    Reported to CDC before any fix, 2006 to 2015

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    EPA predicts 2 to 4 pCi/L indoors

  • Rank in Illinois

    77 of 92

    Lowest quarter

    Hamilton
    22.6%
    Stark
    83.3%

    By share, of 92 with 30+ tests

Read a result for Hamilton County

Starts at Hamilton County's median, 2.0 pCi/L

2.0pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 2.0 pCi/L

Between 2 and 4 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 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. Hamilton County's median reported result, 2006 to 2015.

Interpret this readingWhat a fix costs

The data

Hamilton County, At a glance

Hamilton County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Hamilton County is a county: EPA's forecast for it as a whole is an average indoor of 2 to 4 pCi/L (75 to 150 Bq/m³). It describes no single address, and homes above EPA's are found in every zone, this one included.

USGS geologic potential: Moderate across 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Hamilton County, 2015

Share of reported tests at or above 4 pCi/L, by year, Hamilton County
Share of reported tests at or above 4 pCi/L, by year, Hamilton County
YearShare of reported tests at or above 4 pCi/L
20140.0%
20150.0%

2015: 0.0%. Across these years the share ran from 0.0% to 0.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

Only 6 tests were reported to CDC for Hamilton County over 2015, and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.

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

How to read these figures

Hamilton County, Compared

Hamilton County radon figures, compared

Calculated by Radon411

Hamilton County's 31 reported tests over the 2006 to 2015 laboratory totals had a middle value of 2.0 pCi/L and a maximum of 11.0 pCi/L, and 22.6% reached 4 pCi/L. Illinois as a whole (102 Illinois counties, pooled) comes to 44.3%: 21.7 points higher than here.

The newest figure, in 2015, counts only 6 tests (0.0% at or above 4 pCi/L), too few to compare, so this reading uses the 31-test figure.

Among its state's counties it ranks 77th of 92 Illinois counties with 30 or more tests for the same period. Statewide for the same period, Stark County reported the highest share (83.3%) and Williamson County the lowest (14.1%).

Below the action level, 15 tests (48.4%) came in under 2 pCi/L, against 30.8% statewide, and 9 tests (29.0%) fell between 2 and 4, against 24.9% statewide. The busiest year on file was 2014, with 6 tests reported; the quietest, 2015, had 6.

EPA's 1993 zone map puts Hamilton County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 100% of the county's land moderate radon potential.

Next door, the shares run from 15.1% in Wayne County to 25.0% in White County, with Jefferson County, Saline County and Franklin County below Hamilton County.

Hamilton County against Illinois, the United States and nearby counties, 2006 to 2015, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Hamilton County
Hamilton County3122.6%2.0 pCi/LThis county
Illinois, pooled102 counties, pooled99,33744.3%Not pooled+21.7 points
United States, pooled2,669 counties, pooled1,805,52836.3%Not pooled+13.7 points
Stark Countyhighest in the state6083.3%9.1 pCi/L+60.7 points
Williamson Countylowest in the state61114.1%1.3 pCi/L−8.5 points
White County, ILborders it4025.0%2.5 pCi/L+2.4 points
Jefferson County, ILborders it31522.2%1.9 pCi/L−0.4 points
Saline County, ILborders it8320.5%1.8 pCi/L−2.1 points
Franklin County, ILborders it21019.0%1.8 pCi/L−3.6 points
Wayne County, ILborders it8615.1%1.4 pCi/L−7.5 points
Gallatin County, ILborders it70.0%1.9 pCi/L−22.6 points
Where Hamilton County's reported results fell, 2006 to 2015, laboratory, beside Illinois and the United States
ResultHamilton County testsHamilton County shareIllinois shareU.S. shareAgainst Illinois
Under 2 pCi/L1548.4%30.8%39.4%+17.6 points
2 to 4 pCi/L929.0%24.9%24.3%+4.1 points
4 pCi/L and above722.6%44.3%36.3%−21.7 points
Hamilton County ranked among the 92 Illinois counties with 30 or more tests, by share at or above 4 pCi/L, 2006 to 2015, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Perry County72 of 9218125.4%2.3 pCi/L
White County73 of 924025.0%2.5 pCi/L
Clark County74 of 926924.6%1.8 pCi/L
Washington County75 of 9212623.8%2.5 pCi/L
Union County76 of 9211823.7%1.9 pCi/L
Hamilton County77 of 923122.6%2.0 pCi/L
Jefferson County78 of 9231522.2%1.9 pCi/L
Cumberland County79 of 924721.3%1.7 pCi/L
Cook County80 of 9212,80121.1%1.8 pCi/L
Saline County81 of 928320.5%1.8 pCi/L
Marion County82 of 9238619.9%1.8 pCi/L
Hamilton County radon tests by year, against Illinois' pooled share
YearTestsAt or above 4 pCi/LMedianHighestIllinois, pooledChange from the row before
201560.0%0.8 pCi/L0.9 pCi/L36.6%Level
201460.0%1.3 pCi/L1.3 pCi/L37.8%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Hamilton County, Geology

The ground under Hamilton County

Predicted

USGS's geologic map puts all of Hamilton County's mapped land in one class: moderate radon potential. All of it lies in the area the map calls Southern Central Lowland Province, to which USGS gives a radon index of 9, in the moderate band (9 to 11).

USGS's geologic areas under Hamilton County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Southern Central Lowland ProvinceIllinoian glacial deposits, sandstone, and gray shale.Moderate9100%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Hamilton County beside the ground around it

Across Illinois 64.5% of the land is rated high; none of Hamilton County's is. Of the 6 counties that border it, none has as large a share of moderate-potential ground; Franklin County comes nearest at 100%.

Share of land by USGS radon potential: Hamilton County, the 6 counties bordering it and Illinois
AreaEPA zoneLow potentialModerate potentialHigh potential
Hamilton CountyZone 2None100%None
Saline CountyZone 2None100%None
White CountyZone 2None100%None
Franklin CountyZone 2None100%None
Wayne CountyZone 2None100%None
Gallatin CountyZone 2None100%None
Jefferson CountyZone 2None100%None
Illinois102 counties, pooled by land areaVaries0.9%34.5%64.5%

The map rates the ground, not the air in any home.

Local help

Hamilton County, Local resources

Radon testing and mitigation in Hamilton County

What Illinois's program says
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.

What it means

Hamilton County, Questions

Questions about radon in Hamilton County

Are radon levels high in Hamilton County?

In 2015, 0.0% of the radon tests reported to CDC for Hamilton County, Illinois were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.8 pCi/L. Of 92 Illinois counties with 30 or more tests for the same period, 76 reported a higher share; pooled, the state comes to 44.3%.

Which counties border Hamilton County?

Hamilton County borders 6 counties: Saline County, White County, Franklin County, Wayne County, Gallatin County and Jefferson County.

Products

Hamilton County, Products

Testing a home in Hamilton County

In Hamilton County, 22.6% of 31 tests reported to CDC over the 2006 to 2015 laboratory totals reached 4 pCi/L, against 44.3% pooled across Illinois. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Hamilton County; a long-term test tells the year-round average.

Test kits and monitors3

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Best radon monitors for Hamilton County homes, compared

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Hamilton County, Bordering counties

Counties bordering Hamilton County

Calculated by Radon411

Hamilton County, Cities and towns

Cities and towns in Hamilton County

About 7,859 people live in Hamilton County by the Census Bureau's estimate for July 1, 2025, 137 fewer than in 2020 (−1.7%). That works out to 18 people per square mile of land. Its largest town, McLeansboro, has 2,585 residents, 32.9% of the total. Reported testing is thin here: 31 tests over 2006 to 2015, or 3.9 for every 1,000 residents (2025 estimate), where Illinois as a whole comes to 7.8.

From McLeansboro to Macedonia, CDC publishes no figure by town: each reads Hamilton County's.

The cities and towns in Hamilton County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
McLeansboro2,585−1.9%32.9%
Dahlgren495−1.6%6.3%
Broughton180−1.6%2.3%
Belle Prairie City47−2.1%0.6%
Macedoniaextends beyond Hamilton County27LevelCounted whole

5 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Hamilton County is counted whole, so it has no share.

Hamilton County, Homes

Homes in Hamilton County

Hamilton County is a place of houses on their own lots: 76% of its 3,809 homes are detached single-family houses, against 58% across Illinois. Half of its homes were built before 1971, close to Illinois' 1970: 41% date from before 1960 and 14% from 2000 or later. Owners live in 78% of the occupied homes (Illinois: 67%), so for most households a test and a fix are their own to order.

Homes in Hamilton County, Illinois, 2019 to 2023
HomesHamilton CountyIllinois
Housing units3,8095,443,501
Detached houses76%58%
In buildings of 5 or more4%22%
Mobile homes18%2%
Built before 196041%38%
Built since 200014%16%
Middle year built19711970
Owner-occupied78%67%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.