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Radon Levels in Macoupin County, Illinois

EPA puts Macoupin County in Zone 2, its middle radon zone, and 25.6% of its 258 reported radon tests (2017) were at or above 4 pCi/L. 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

    25.6%

    8.1 pts below IL

    Macoupin
    25.6%
    Illinois
    33.7%

    258 tests, 2017

  • Median result

    2.2pCi/L

    Below action level

    Macoupin
    2.2 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2017

  • Tests reported

    258

    36th of 70 by tests

    Macoupin
    258
    Cook
    26,937

    Reported to CDC before any fix, 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

    61 of 70

    Lowest quarter

    Macoupin
    25.6%
    Stark
    69.2%

    By share, of 70 with 30+ tests

Read a result for Macoupin County

Starts at Macoupin County's median, 2.2 pCi/L

2.2pCi/L

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

EPA’s reading of 2.2 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. Macoupin County's median reported result, 2017.

Interpret this readingWhat a fix costs

The data

Macoupin County, At a glance

Macoupin County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Macoupin 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: High across 58% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Macoupin County, 2017

Share of reported tests at or above 4 pCi/L, by year, Macoupin County
Share of reported tests at or above 4 pCi/L, by year, Macoupin County
YearShare of reported tests at or above 4 pCi/L
201426.2%
201529.0%
201725.6%

2017: 25.6%. Across these years the share ran from 25.6% to 29.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 258 tests reported to CDC for Macoupin County over 2017, many from homes being sold or already suspected of a problem: they describe the county's reported tests, not 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

Macoupin County, Compared

Macoupin County radon figures, compared

Calculated by Radon411

Macoupin County's 258 reported tests in 2017 had a middle value of 2.2 pCi/L and a maximum of 19.4 pCi/L, and 25.6% reached 4 pCi/L. Illinois as a whole (93 Illinois counties, pooled) comes to 33.7%: 8.1 points higher than here.

Among its state's counties it ranks 61st of 70 Illinois counties with 30 or more tests for the same period. Statewide for the same period, Stark County reported the highest share (69.2%) and Williamson County the lowest (8.4%).

Below the action level, 105 tests (40.7%) came in under 2 pCi/L, against 37.7% statewide, and 87 tests (33.7%) fell between 2 and 4, against 28.6% statewide. The busiest year on file was 2014, with 447 tests reported; the quietest, 2015, had 207.

EPA's 1993 zone map puts Macoupin County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 58% of the county's land high radon potential.

Next door, the shares run from 29.5% in Madison County to 66.9% in Morgan County. Over 3 years of annual figures the share held within 2 points, from 26.2% in 2014 to 25.6% in 2017; its peak was 29.0% in 2015.

Share of reported tests at or above 4 pCi/L by year, Macoupin County against Illinois2014 to 2017, years with 30 or more tests: Macoupin County 26.2% to 25.6%, the state's pooled share 33.7% in 2017.
Macoupin CountyIllinois, pooled
Share of reported tests at or above 4 pCi/L by year, Macoupin County against Illinois: data table
YearTestsMacoupin County, at or above 4 pCi/LIllinois, pooled
201444726.2%37.8%
201520729.0%36.6%
201725825.6%33.7%
Macoupin County against Illinois, the United States and nearby counties, 2017
AreaTestsAt or above 4 pCi/LMedianDifference from Macoupin County
Macoupin County25825.6%2.2 pCi/LThis county
Illinois, pooled93 counties, pooled138,00633.7%Not pooled+8.1 points
United States, pooled937 counties, pooled528,06231.7%Not pooled+6.1 points
Stark Countyhighest in the state3969.2%5.8 pCi/L+43.6 points
Williamson Countylowest in the state2498.4%0.9 pCi/L−17.2 points
Morgan County, ILborders it38166.9%6.5 pCi/L+41.3 points
Jersey County, ILborders it12946.5%3.6 pCi/L+20.9 points
Montgomery County, ILborders it12343.9%3.3 pCi/L+18.3 points
Sangamon County, ILborders it3,37843.7%3.7 pCi/L+18.1 points
Madison County, ILborders it5,21429.5%2.6 pCi/L+3.9 points
Greene County, ILborders it120.0%2.7 pCi/L−25.6 points
Where Macoupin County's reported results fell, 2017, beside Illinois and the United States
ResultMacoupin County testsMacoupin County shareIllinois shareU.S. shareAgainst Illinois
Under 2 pCi/L10540.7%37.7%43.5%+3.0 points
2 to 4 pCi/L8733.7%28.6%24.8%+5.1 points
4 pCi/L and above6625.6%33.7%31.7%−8.1 points
Macoupin County ranked among the 70 Illinois counties with 30 or more tests, by share at or above 4 pCi/L, 2017
CountyRankTestsAt or above 4 pCi/LMedian
Bond County56 of 707532.0%2.6 pCi/L
Kankakee County57 of 7052231.6%2.7 pCi/L
Madison County58 of 705,21429.5%2.6 pCi/L
Lake County59 of 7013,05027.4%2.4 pCi/L
Fayette County60 of 705726.3%2.5 pCi/L
Macoupin County61 of 7025825.6%2.2 pCi/L
Jackson County62 of 709625.0%2.5 pCi/L
Iroquois County62 of 703625.0%1.9 pCi/L
Mason County64 of 704221.4%2.8 pCi/L
Marion County65 of 704520.0%1.9 pCi/L
Jefferson County66 of 7013819.6%1.9 pCi/L
Macoupin County radon tests by year, against Illinois' pooled share
YearTestsAt or above 4 pCi/LMedianHighestIllinois, pooledChange from the row before
201725825.6%2.2 pCi/L19.4 pCi/L33.7%−3.4 points
201520729.0%2.3 pCi/L17.7 pCi/L36.6%+2.8 points
201444726.2%2.1 pCi/L11.1 pCi/L37.8%First on file

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

Macoupin County, Geology

The ground under Macoupin County

Predicted

USGS's geologic map splits Macoupin County: 57.6% of its land is high radon potential and 42.4% moderate. The map puts 57.6% of Macoupin County in the area it calls Galesburg Plain and 42.4% in Southern Central Lowland Province. USGS gives the first a radon index of 13, in the high band (12 to 17), and the second 9, in the moderate band (9 to 11).

USGS's geologic areas under Macoupin County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Galesburg PlainIllinoian glacial deposits and loess over Paleozoic sedimentary rocks.High1357.6%
Southern Central Lowland ProvinceIllinoian glacial deposits, sandstone, and gray shale.Moderate942.4%

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

Macoupin County beside the ground around it

On high-potential ground Macoupin County is close to Illinois as a whole: 57.6% of its land against 64.5%. Of the 6 counties that border it, 4 have more high-potential ground, Greene County the most at 100%.

Share of land by USGS radon potential: Macoupin County, the 6 counties bordering it and Illinois
AreaEPA zoneLow potentialModerate potentialHigh potential
Macoupin CountyZone 2None42.4%57.6%
Madison CountyZone 2None91.7%8.3%
Jersey CountyZone 1None0.4%99.6%
Greene CountyZone 1NoneNone100%
Montgomery CountyZone 2None88.8%11.2%
Morgan CountyZone 1NoneNone100%
Sangamon CountyZone 1NoneNone100%
Illinois102 counties, pooled by land areaVaries0.9%34.5%64.5%

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

Local help

Macoupin County, Local resources

Radon testing and mitigation in Macoupin County

Listed radon businesses with an address in Macoupin County:

Listed radon professionals by town: Girard

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

Macoupin County, Questions

Questions about radon in Macoupin County

Are radon levels high in Macoupin County?

In 2017, 25.6% of the radon tests reported to CDC for Macoupin County, Illinois were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.2 pCi/L. Of 70 Illinois counties with 30 or more tests for the same period, 60 reported a higher share; pooled, the state comes to 33.7%.

Which counties border Macoupin County?

Macoupin County borders 6 counties: Madison County, Jersey County, Greene County, Montgomery County, Morgan County and Sangamon County.

Products

Macoupin County, Products

Testing a home in Macoupin County

In Macoupin County, 25.6% of 258 tests reported to CDC in 2017 reached 4 pCi/L, against 33.7% pooled across Illinois. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Macoupin County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Macoupin County homes, compared

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Macoupin County, Bordering counties

Counties bordering Macoupin County

Calculated by Radon411

Macoupin County, Cities and towns

Cities and towns in Macoupin County

About 43,748 people live in Macoupin County by the Census Bureau's estimate for July 1, 2025, 1,181 fewer than in 2020 (−2.6%). That works out to 51 people per square mile of land. No town dominates: Carlinville, the largest, has 5,465 residents, 12.5% of the total. Reported testing is thin here: 258 tests over 2017, or 5.9 for every 1,000 residents (2025 estimate), where Illinois as a whole comes to 10.9.

From Carlinville to Scottville, CDC publishes no figure by town: each reads Macoupin County's.

The 12 largest cities and towns in Macoupin County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Carlinville5,465−5.0%12.5%
Staunton4,932−2.2%11.3%
Virdenextends beyond Macoupin County3,149−2.4%Counted whole
Gillespie3,083−2.6%7.0%
Brightonextends beyond Macoupin County2,162−2.4%Counted whole
Mount Olive1,936−3.8%4.4%
Girard1,768−2.4%4.0%
Bunker Hill1,593−2.3%3.6%
Benld1,403−4.5%3.2%
Palmyra591−1.7%1.4%
Wilsonville529−2.4%1.2%
Shipman504−1.8%1.2%
  • Medora (part)
  • Mount Clare
  • Sawyerville
  • East Gillespie
  • White City
  • Lake Ka-Ho
  • Nilwood
  • Modesto
  • Royal Lakes
  • Chesterfield
  • Hettick
  • Standard City
  • Dorchester
  • Eagarville
  • Scottville

27 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Macoupin County is counted whole, so it has no share.

Macoupin County, Homes

Homes in Macoupin County

Macoupin County is a place of houses on their own lots: 82% of its 21,108 homes are detached single-family houses, against 58% across Illinois. Half of its homes were built before 1966, close to Illinois' 1970: 45% 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 Macoupin County, Illinois, 2019 to 2023
HomesMacoupin CountyIllinois
Housing units21,1085,443,501
Detached houses82%58%
In buildings of 5 or more3%22%
Mobile homes8%2%
Built before 196045%38%
Built since 200014%16%
Middle year built19661970
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.