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Radon Levels in Cumberland County, Illinois

EPA puts Cumberland County in Zone 2, its middle radon zone, and only 12 radon tests from it are on file with CDC (2017). 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

    21.8%

    21.3 pts below IL

    Cumberland
    21.8%
    Illinois
    43.1%

    55 tests, 2008 to 2017

  • Median result

    1.8pCi/L

    Below action level

    Cumberland
    1.8 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    55

    83rd of 93 by tests

    Cumberland
    55
    Cook
    14,199

    Reported to CDC before any fix, 2008 to 2017

  • 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

    81 of 93

    Lowest quarter

    Cumberland
    21.8%
    Stark
    80.5%

    By share, of 93 with 30+ tests

Read a result for Cumberland County

Starts at Cumberland County's median, 1.8 pCi/L

1.8pCi/L

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

EPA’s reading of 1.8 pCi/L

Below 2 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 below 2 pCi/L, the level at which EPA says a fix should be considered. Cumberland County's median reported result, 2008 to 2017.

Interpret this reading

The data

Cumberland County, At a glance

Cumberland County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Cumberland 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 95% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Cumberland County, 2017

Share of reported tests at or above 4 pCi/L, by year, Cumberland County
Share of reported tests at or above 4 pCi/L, by year, Cumberland County
YearShare of reported tests at or above 4 pCi/L
20140.0%
20150.0%
201725.0%

2017: 25.0%. Across these years the share ran from 0.0% to 25.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

Only 12 tests were reported to CDC for Cumberland County over 2017, 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: 2017. Measured data period: 2005 to 2017 (every CDC figure on file).

How to read these figures

Cumberland County, Compared

Cumberland County radon figures, compared

Calculated by Radon411

Cumberland County's 55 reported tests over the 2008 to 2017 laboratory totals had a middle value of 1.8 pCi/L and a maximum of 10.1 pCi/L, and 21.8% reached 4 pCi/L. Illinois as a whole (102 Illinois counties, pooled) comes to 43.1%: 21.3 points higher than here.

The newest figure, in 2017, counts only 12 tests (25.0% at or above 4 pCi/L), too few to compare, so this reading uses the 55-test figure.

Among its state's counties it ranks 81st of 93 Illinois counties with 30 or more tests for the same period. Statewide for the same period, Stark County reported the highest share (80.5%) and Williamson County the lowest (13.3%).

Below the action level, 30 tests (54.5%) came in under 2 pCi/L, against 31.6% statewide, and 13 tests (23.6%) fell between 2 and 4, against 25.3% statewide. The busiest year on file was 2014, with 18 tests reported; the quietest, 2015, had 6.

EPA's 1993 zone map puts Cumberland County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 95% of the county's land moderate radon potential.

Next door, the shares run from 22.1% in Clark County to 56.6% in Shelby County.

Cumberland County against Illinois, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Cumberland County
Cumberland County5521.8%1.8 pCi/LThis county
Illinois, pooled102 counties, pooled108,90943.1%Not pooled+21.3 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+13.9 points
Stark Countyhighest in the state8780.5%7.4 pCi/L+58.7 points
Williamson Countylowest in the state60113.3%1.3 pCi/L−8.5 points
Shelby County, ILborders it11356.6%4.4 pCi/L+34.8 points
Coles County, ILborders it29538.6%3.1 pCi/L+16.8 points
Effingham County, ILborders it76337.9%3.0 pCi/L+16.1 points
Jasper County, ILborders it7623.7%1.9 pCi/L+1.9 points
Clark County, ILborders it7722.1%2.0 pCi/L+0.3 points
Where Cumberland County's reported results fell, 2008 to 2017, laboratory, beside Illinois and the United States
ResultCumberland County testsCumberland County shareIllinois shareU.S. shareAgainst Illinois
Under 2 pCi/L3054.5%31.6%39.6%+22.9 points
2 to 4 pCi/L1323.6%25.3%24.7%−1.7 points
4 pCi/L and above1221.8%43.1%35.7%−21.3 points
Cumberland County ranked among the 93 Illinois counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Union County76 of 938725.3%1.9 pCi/L
Jasper County77 of 937623.7%1.9 pCi/L
Hamilton County78 of 933023.3%1.9 pCi/L
Jefferson County79 of 9332022.2%1.9 pCi/L
Clark County80 of 937722.1%2.0 pCi/L
Cumberland County81 of 935521.8%1.8 pCi/L
Saline County82 of 938220.7%1.7 pCi/L
Marion County83 of 9336420.6%1.7 pCi/L
Cook County84 of 9314,19920.2%1.8 pCi/L
Franklin County85 of 9319919.6%1.8 pCi/L
Crawford County86 of 9318119.3%1.8 pCi/L
Cumberland County radon tests by year, against Illinois' pooled share
YearTestsAt or above 4 pCi/LMedianHighestIllinois, pooledChange from the row before
20171225.0%2.8 pCi/L10.1 pCi/L33.7%+25.0 points
201560.0%2.3 pCi/L3.8 pCi/L36.6%Level
2014180.0%2.6 pCi/L3.5 pCi/L37.8%First on file

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

Cumberland County, Geology

The ground under Cumberland County

Predicted

Most of the ground under Cumberland County is one class on USGS's geologic map: 94.7% of its land is moderate radon potential, with 5.3% high. The map puts 94.7% of Cumberland County in the area it calls Southern Central Lowland Province and 5.3% in Bloomington Ridged Plain. USGS gives the first a radon index of 9, in the moderate band (9 to 11), and the second 13, in the high band (12 to 17).

USGS's geologic areas under Cumberland County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Southern Central Lowland ProvinceIllinoian glacial deposits, sandstone, and gray shale.Moderate994.7%
Bloomington Ridged PlainWisconsinan glacial deposits and loess over Paleozoic sedimentary rocks.High135.3%

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

Cumberland County beside the ground around it

Illinois as a whole has more high-potential ground than Cumberland County: 64.5% of its land, against 5.3% here. Of the 5 counties that border it, 2 have more high-potential ground, Coles County the most at 98.1%.

Share of land by USGS radon potential: Cumberland County, the 5 counties bordering it and Illinois
AreaEPA zoneLow potentialModerate potentialHigh potential
Cumberland CountyZone 2None94.7%5.3%
Jasper CountyZone 2None100%None
Coles CountyZone 1None1.9%98.1%
Clark CountyZone 2None96.5%3.5%
Effingham CountyZone 2None100%None
Shelby CountyZone 2None54.9%45.1%
Illinois102 counties, pooled by land areaVaries0.9%34.5%64.5%

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

Local help

Cumberland County, Local resources

Radon testing and mitigation in Cumberland 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

Cumberland County, Questions

Questions about radon in Cumberland County

Are radon levels high in Cumberland County?

In 2017, 25.0% of the radon tests reported to CDC for Cumberland County, Illinois were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.8 pCi/L. Of 93 Illinois counties with 30 or more tests for the same period, 80 reported a higher share; pooled, the state comes to 43.1%.

Which counties border Cumberland County?

Cumberland County borders 5 counties: Jasper County, Coles County, Clark County, Effingham County and Shelby County.

Products

Cumberland County, Products

Testing a home in Cumberland County

In Cumberland County, 21.8% of 55 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 43.1% pooled across Illinois. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Cumberland County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Cumberland County homes, compared

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Cumberland County, Bordering counties

Counties bordering Cumberland County

Calculated by Radon411

Cumberland County, Cities and towns

Cities and towns in Cumberland County

About 10,208 people live in Cumberland County by the Census Bureau's estimate for July 1, 2025, 224 fewer than in 2020 (−2.1%). That works out to 30 people per square mile of land. Casey, the largest place on its list (2,374 residents in all), extends beyond Cumberland County, so no share of the total is worked out for it. Reported testing is thin here: 55 tests over 2008 to 2017, or 5.4 for every 1,000 residents (2025 estimate), where Illinois as a whole comes to 8.6.

From Casey to Jewett, CDC publishes no figure by town: each reads Cumberland County's.

The cities and towns in Cumberland County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Caseyextends beyond Cumberland County2,374−2.3%Counted whole
Neoga1,369−2.1%13.4%
Greenup1,330−2.3%13.0%
Toledo1,140−2.0%11.2%
Montroseextends beyond Cumberland County211−0.9%Counted whole
Jewett186−2.1%1.8%

6 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 Cumberland County is counted whole, so it has no share.

Cumberland County, Homes

Homes in Cumberland County

Cumberland County is a place of houses on their own lots: 84% of its 4,720 homes are detached single-family houses, against 58% across Illinois. Half of its homes were built before 1969, close to Illinois' 1970: 39% date from before 1960 and 14% from 2000 or later. Owners live in 83% of the occupied homes (Illinois: 67%), so for most households a test and a fix are their own to order.

Homes in Cumberland County, Illinois, 2019 to 2023
HomesCumberland CountyIllinois
Housing units4,7205,443,501
Detached houses84%58%
In buildings of 5 or more1%22%
Mobile homes10%2%
Built before 196039%38%
Built since 200014%16%
Middle year built19691970
Owner-occupied83%67%

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