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Radon Levels in Morgan County, Illinois

EPA puts Morgan County in Zone 1, its highest radon zone, and high results are common there: 66.9% of the 381 radon tests reported to CDC (2017) came back 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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    66.9%

    33.2 pts above IL

    Morgan
    66.9%
    Illinois
    33.7%

    381 tests, 2017

  • Median result

    6.5pCi/L

    Action level reached

    Morgan
    6.5 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2017

  • Tests reported

    381

    32nd of 70 by tests

    Morgan
    381
    Cook
    26,937

    Reported to CDC before any fix, 2017

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    EPA predicts over 4 pCi/L indoors

  • Rank in Illinois

    3 of 70

    Top quarter

    Morgan
    66.9%
    Stark
    69.2%

    By share, of 70 with 30+ tests

Read a result for Morgan County

Starts at Morgan County's median, 6.5 pCi/L

6.5pCi/L

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

EPA’s reading of 6.5 pCi/L

At or above 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 at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. Morgan County's median reported result, 2017.

Interpret this readingWhat a fix costs

The data

Morgan County, At a glance

Morgan County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Morgan County in and predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county. That is one forecast for the whole county, not a reading of any address in it; homes above EPA's turn up in all three zones.

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

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Morgan County, 2017

Share of reported tests at or above 4 pCi/L, by year, Morgan County
Share of reported tests at or above 4 pCi/L, by year, Morgan County
YearShare of reported tests at or above 4 pCi/L
201453.9%
201539.7%
201766.9%

2017: 66.9%. Across these years the share ran from 39.7% to 66.9%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 381 tests reported to CDC for Morgan 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

Morgan County, Compared

Morgan County radon figures, compared

Calculated by Radon411

More than half: 66.9% of the 381 radon tests reported to CDC for Morgan County in 2017 read at least 4 pCi/L. That places it 3rd of 70 Illinois counties with 30 or more tests for the same period. That is 33.2 points above the 33.7% pooled from 93 Illinois counties.

The median result, 6.5 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 43.0 pCi/L. The rest split 15.0% under 2 pCi/L and 18.1% from 2 to 4 (Illinois: 37.7% and 28.6%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 66.9% share point the same way here.

No bordering county with a figure for the same period reported a higher share; the closest is Sangamon County at 43.7%, the lowest Macoupin County at 25.6%. Statewide for the same period, Stark County reported the highest share (69.2%) and Williamson County the lowest (8.4%).

The busiest year on file was 2014, with 501 tests reported; the quietest, 2015, had 189.

Over 3 years of annual figures the share rose 13.0 points, from 53.9% in 2014 to 66.9% in 2017; its peak was 66.9% in 2017. Nationally, every county with a figure for the same period pools to 31.7%; Morgan County sits 35.2 points above it.

Share of reported tests at or above 4 pCi/L by year, Morgan County against Illinois2014 to 2017, years with 30 or more tests: Morgan County 53.9% to 66.9%, the state's pooled share 33.7% in 2017.
Morgan CountyIllinois, pooled
Share of reported tests at or above 4 pCi/L by year, Morgan County against Illinois: data table
YearTestsMorgan County, at or above 4 pCi/LIllinois, pooled
201450153.9%37.8%
201518939.7%36.6%
201738166.9%33.7%
Morgan County against Illinois, the United States and nearby counties, 2017
AreaTestsAt or above 4 pCi/LMedianDifference from Morgan County
Morgan County38166.9%6.5 pCi/LThis county
Illinois, pooled93 counties, pooled138,00633.7%Not pooled−33.2 points
United States, pooled937 counties, pooled528,06231.7%Not pooled−35.2 points
Stark Countyhighest in the state3969.2%5.8 pCi/L+2.3 points
Williamson Countylowest in the state2498.4%0.9 pCi/L−58.5 points
Brown County, ILborders it1850.0%4.0 pCi/L−16.9 points
Sangamon County, ILborders it3,37843.7%3.7 pCi/L−23.2 points
Macoupin County, ILborders it25825.6%2.2 pCi/L−41.3 points
Pike County, ILborders it1225.0%2.8 pCi/L−41.9 points
Cass County, ILborders it2425.0%2.9 pCi/L−41.9 points
Scott County, ILborders it90.0%1.6 pCi/L−66.9 points
Greene County, ILborders it120.0%2.7 pCi/L−66.9 points
Where Morgan County's reported results fell, 2017, beside Illinois and the United States
ResultMorgan County testsMorgan County shareIllinois shareU.S. shareAgainst Illinois
Under 2 pCi/L5715.0%37.7%43.5%−22.7 points
2 to 4 pCi/L6918.1%28.6%24.8%−10.5 points
4 pCi/L and above25566.9%33.7%31.7%+33.2 points
Morgan 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
Stark County1 of 703969.2%5.8 pCi/L
Mercer County2 of 706668.2%5.5 pCi/L
Morgan County3 of 7038166.9%6.5 pCi/L
Fulton County4 of 7014464.6%5.8 pCi/L
Carroll County5 of 7021062.9%5.5 pCi/L
Livingston County6 of 7034561.7%5.3 pCi/L
Bureau County7 of 7033358.6%5.1 pCi/L
Stephenson County8 of 7051957.2%4.8 pCi/L
De Witt County9 of 7012657.1%5.2 pCi/L
Ford County9 of 704257.1%4.0 pCi/L
Knox County11 of 7024956.6%4.7 pCi/L
Morgan County radon tests by year, against Illinois' pooled share
YearTestsAt or above 4 pCi/LMedianHighestIllinois, pooledChange from the row before
201738166.9%6.5 pCi/L43.0 pCi/L33.7%+27.2 points
201518939.7%3.3 pCi/L27.2 pCi/L36.6%−14.2 points
201450153.9%4.6 pCi/L21.0 pCi/L37.8%First on file

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

Morgan County, Geology

The ground under Morgan County

Predicted

USGS's geologic map puts all of Morgan County's mapped land in one class: high radon potential. All of it lies in the area the map calls Galesburg Plain, to which USGS gives a radon index of 13, in the high band (12 to 17).

USGS's geologic areas under Morgan County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Galesburg PlainIllinoian glacial deposits and loess over Paleozoic sedimentary rocks.High13100%

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

Morgan County beside the ground around it

Morgan County has more high-potential ground than Illinois as a whole: 100% of its land against 64.5%. Of the 7 counties that border it, none has as large a share of high-potential ground; Brown County comes nearest at 100%.

Share of land by USGS radon potential: Morgan County, the 7 counties bordering it and Illinois
AreaEPA zoneLow potentialModerate potentialHigh potential
Morgan CountyZone 1NoneNone100%
Scott CountyZone 1NoneNone100%
Cass CountyZone 1NoneNone100%
Sangamon CountyZone 1NoneNone100%
Greene CountyZone 1NoneNone100%
Brown CountyZone 1NoneNone100%
Pike CountyZone 1None0.1%99.9%
Macoupin CountyZone 2None42.4%57.6%
Illinois102 counties, pooled by land areaVaries0.9%34.5%64.5%

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

Local help

Morgan County, Local resources

Radon testing and mitigation in Morgan County

Listed radon businesses with an address in Morgan County:

Listed radon professionals by town: Jacksonville

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

Morgan County, Questions

Questions about radon in Morgan County

Are radon levels high in Morgan County?

In 2017, 66.9% of the radon tests reported to CDC for Morgan County, Illinois were at or above 4 pCi/L, and the median reported pre-mitigation result was 6.5 pCi/L. Of 70 Illinois counties with 30 or more tests for the same period, 2 reported a higher share; pooled, the state comes to 33.7%.

Which counties border Morgan County?

Morgan County borders 7 counties: Scott County, Cass County, Sangamon County, Greene County, Brown County, Pike County and Macoupin County.

Products

Morgan County, Products

Testing a home in Morgan County

In Morgan County, 66.9% of 381 tests reported to CDC in 2017 reached 4 pCi/L, against 33.7% pooled across Illinois. In Zone 1 the year-round level in Morgan County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.

Test kits and monitors3

See every kit and monitor

Morgan County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Morgan County

Explore

Morgan County, Bordering counties

Counties bordering Morgan County

Calculated by Radon411

Morgan County, Cities and towns

Cities and towns in Morgan County

About 32,515 people live in Morgan County by the Census Bureau's estimate for July 1, 2025, 975 fewer than in 2020 (−2.9%). That works out to 57 people per square mile of land. Jacksonville alone is home to 17,752 of them, 54.6% of the total. Together its 10 incorporated places hold 77.5% of those residents; the other 22.5% live outside any of them. CDC's 381 reported tests for 2017 work out to 11.7 per 1,000 residents (2025 estimate), close to Illinois' 10.9.

From Jacksonville to Lynnville, CDC publishes no figure by town: each reads Morgan County's.

The cities and towns in Morgan County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Jacksonville17,752−2.7%54.6%
South Jacksonville3,195−3.0%9.8%
Waverly1,142−3.8%3.5%
Meredosia795−2.9%2.4%
Franklin587−3.6%1.8%
Murrayville546−3.2%1.7%
Woodson483−3.0%1.5%
Chapin457−3.8%1.4%
Concord150−3.2%0.5%
Lynnville93−3.1%0.3%

10 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).

Morgan County, Homes

Homes in Morgan County

Morgan County is a place of houses on their own lots: 76% of its 15,033 homes are detached single-family houses, against 58% across Illinois. Half of its homes were built before 1966, close to Illinois' 1970: 42% date from before 1960 and 10% from 2000 or later. 72% of occupied homes are lived in by their owner (Illinois: 67%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Morgan County, Illinois, 2019 to 2023
HomesMorgan CountyIllinois
Housing units15,0335,443,501
Detached houses76%58%
In buildings of 5 or more7%22%
Mobile homes7%2%
Built before 196042%38%
Built since 200010%16%
Middle year built19661970
Owner-occupied72%67%

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