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Radon Levels in Custer County, Nebraska

EPA puts Custer County in Zone 2, its middle radon zone, and only 14 radon tests from it are on file with CDC (2023). 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

    52.3%

    6.2 pts below NE

    Custer
    52.3%
    Nebraska
    58.5%

    132 tests, 2008 to 2017

  • Median result

    4.2pCi/L

    Action level reached

    Custer
    4.2 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    132

    52nd of 77 by tests

    Custer
    132
    Douglas
    8,556

    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 Nebraska

    58 of 77

    Middle half

    Custer
    52.3%
    Clay
    85.1%

    By share, of 77 with 30+ tests

Read a result for Custer County

Starts at Custer County's median, 4.2 pCi/L

4.2pCi/L

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

EPA’s reading of 4.2 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. Custer County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Custer County, At a glance

Custer County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Custer 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 91% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Custer County, 2023

Share of reported tests at or above 4 pCi/L, by year, Custer County
Share of reported tests at or above 4 pCi/L, by year, Custer County
YearShare of reported tests at or above 4 pCi/L
201440.0%
201552.4%
201640.0%
201744.8%
201844.4%
201947.4%
202052.6%
202142.1%
202251.7%
202350.0%

2023: 50.0%. Across these years the share ran from 40.0% to 52.6%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

Only 14 tests were reported to CDC for Custer County over 2023, 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: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).

How to read these figures

Custer County, Compared

Custer County radon figures, compared

Calculated by Radon411

More than half: 52.3% of the 132 radon tests reported to CDC for Custer County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 58th of 77 Nebraska counties with 30 or more tests for the same period. That is 6.2 points below the 58.5% pooled from 93 Nebraska counties.

The newest figure, in 2023, counts only 14 tests (50.0% at or above 4 pCi/L), too few to compare, so this reading uses the 132-test figure.

The median result, 4.2 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 25.2 pCi/L. The rest split 16.7% under 2 pCi/L and 31.1% from 2 to 4 (Nebraska: 18.6% and 22.8%). The reported tests do not follow EPA's Zone 2 label for Custer County (predicted average between 2 and 4 pCi/L): 52.3% of them reached 4 pCi/L, fewer than that label suggests.

2 of its 5 bordering counties with figures ran higher, led by Buffalo County at 56.6%; Lincoln County reported 27.0%. Statewide for the same period, Clay County reported the highest share (85.1%) and Cherry County the lowest (13.3%).

The busiest year on file was 2019, with 114 tests reported; the quietest, 2023, had 14.

Over 8 years of annual figures the share rose 2.1 points, from 40.0% in 2014 to 42.1% in 2021; its peak was 52.6% in 2020. Nationally, every county with a figure for the same period pools to 35.7%; Custer County sits 16.6 points above it. CDC also counts 8 tests taken after mitigation in Custer County for the same period: tests in homes where a fix was already in.

Share of reported tests at or above 4 pCi/L by year, Custer County against Nebraska2014 to 2021, years with 30 or more tests: Custer County 40.0% to 42.1%, the state's pooled share 34.9% in 2021.
Custer CountyNebraska, pooled
Share of reported tests at or above 4 pCi/L by year, Custer County against Nebraska: data table
YearTestsCuster County, at or above 4 pCi/LNebraska, pooled
20144540.0%50.5%
20156352.4%53.3%
201610540.0%47.4%
20178744.8%47.7%
20188144.4%44.5%
201911447.4%44.3%
20205752.6%42.2%
20215742.1%34.9%
Custer County against Nebraska, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Custer County
Custer County13252.3%4.2 pCi/LThis county
Nebraska, pooled93 counties, pooled42,78258.5%Not pooled+6.2 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−16.6 points
Clay Countyhighest in the state19485.1%8.6 pCi/L+32.8 points
Cherry Countylowest in the state3013.3%1.7 pCi/L−39.0 points
Buffalo County, NEborders it96856.6%4.4 pCi/L+4.3 points
Valley County, NEborders it8452.4%4.2 pCi/L+0.1 points
Sherman County, NEborders it9148.4%3.9 pCi/L−3.9 points
Dawson County, NEborders it23942.7%3.2 pCi/L−9.6 points
Garfield County, NEborders it2927.6%2.3 pCi/L−24.7 points
Lincoln County, NEborders it89527.0%2.6 pCi/L−25.3 points
Logan County, NEborders it812.5%2.3 pCi/L−39.8 points
Loup County, NEborders it156.7%1.1 pCi/L−45.6 points
Blaine County, NEborders it30.0%0.7 pCi/L−52.3 points
Where Custer County's reported results fell, 2008 to 2017, laboratory, beside Nebraska and the United States
ResultCuster County testsCuster County shareNebraska shareU.S. shareAgainst Nebraska
Under 2 pCi/L2216.7%18.6%39.6%−1.9 points
2 to 4 pCi/L4131.1%22.8%24.7%+8.3 points
4 pCi/L and above6952.3%58.5%35.7%−6.2 points
Custer County ranked among the 77 Nebraska counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Keith County53 of 7712055.0%4.3 pCi/L
Sarpy County54 of 774,79953.6%4.3 pCi/L
Frontier County55 of 774353.5%4.3 pCi/L
Cheyenne County56 of 7729253.4%4.1 pCi/L
Valley County57 of 778452.4%4.2 pCi/L
Custer County58 of 7713252.3%4.2 pCi/L
Hitchcock County59 of 773151.6%4.2 pCi/L
Platte County60 of 7798151.5%4.1 pCi/L
Douglas County61 of 778,55651.1%4.0 pCi/L
Perkins County62 of 774050.0%4.0 pCi/L
Sherman County63 of 779148.4%3.9 pCi/L
Custer County radon tests by year, against Nebraska's pooled share
YearTestsAt or above 4 pCi/LMedianHighestNebraska, pooledChange from the row before
20231450.0%4.0 pCi/L12.1 pCi/L38.2%−1.7 points
20222951.7%4.3 pCi/L10.8 pCi/L34.0%+9.6 points
20215742.1%3.6 pCi/L15.5 pCi/L34.9%−10.5 points
20205752.6%4.0 pCi/L8.5 pCi/L42.2%+5.2 points
201911447.4%3.9 pCi/L24.9 pCi/L44.3%+3.0 points
20188144.4%3.6 pCi/L9.2 pCi/L44.5%−0.4 points
20178744.8%3.7 pCi/L11.3 pCi/L47.7%+4.8 points
201610540.0%3.4 pCi/L16.4 pCi/L47.4%−12.4 points
20156352.4%4.0 pCi/L9.2 pCi/L53.3%+12.4 points
20144540.0%3.5 pCi/L7.8 pCi/L50.5%First on file

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

Custer County, Geology

The ground under Custer County

Predicted

Most of the ground under Custer County is one class on USGS's geologic map: 91.0% of its land is moderate radon potential, with 9.0% low. The map puts 91.0% of Custer County in the area it calls Loess over Tertiary sediments and 9.0% in Sand Hills. USGS gives the first a radon index of 11, in the moderate band (9 to 11), and the second 8, in the low band (5 to 8).

USGS's geologic areas under Custer County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Loess over Tertiary sedimentsTertiary bedrock covered by varying thicknesses of loess.Moderate1191.0%
Sand HillsQuaternary windblown sand.Low89.0%

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

Custer County beside the ground around it

Across Nebraska 40.9% of the land is rated high; none of Custer County's is. Of the 9 counties that border it, 3 have more high-potential ground, Lincoln County the most at 25.2%.

Share of land by USGS radon potential: Custer County, the 9 counties bordering it and Nebraska
AreaEPA zoneLow potentialModerate potentialHigh potential
Custer CountyZone 29.0%91.0%None
Dawson CountyZone 2None76.1%23.9%
Blaine CountyZone 399.2%0.8%None
Loup CountyZone 393.4%6.6%None
Valley CountyZone 23.3%95.9%0.7%
Logan CountyZone 366.4%33.6%None
Sherman CountyZone 2None100%None
Buffalo CountyZone 2None100%None
Garfield CountyZone 380.1%19.9%None
Lincoln CountyZone 362.2%12.6%25.2%
Nebraska93 counties, pooled by land areaVaries28.2%30.9%40.9%

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

Local help

Custer County, Local resources

Radon testing and mitigation in Custer County

What Nebraska's program says
Phone
(402) 471-1005
Licensing of radon professionals
If radon testing is done in schools, offices, or other places of work, it must be done by a licensed radon measurement business.

What it means

Custer County, Questions

Questions about radon in Custer County

Are radon levels high in Custer County?

In 2023, 50.0% of the radon tests reported to CDC for Custer County, Nebraska were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.0 pCi/L. Of 77 Nebraska counties with 30 or more tests for the same period, 57 reported a higher share; pooled, the state comes to 58.5%.

Which counties border Custer County?

Custer County borders 9 counties: Dawson County, Blaine County, Loup County, Valley County, Logan County, Sherman County, Buffalo County, Garfield County and Lincoln County.

Products

Custer County, Products

Testing a home in Custer County

In Custer County, 52.3% of 132 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 58.5% pooled across Nebraska. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Custer County; a long-term test tells the year-round average.

Test kits and monitors3

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Best radon monitors for Custer County homes, compared

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Custer County, Bordering counties

Counties bordering Custer County

Calculated by Radon411

Custer County, Cities and towns

Cities and towns in Custer County

Custer County's population has barely moved since 2020: 10,500 residents on July 1, 2025 against 10,496 then, by the Census Bureau's estimates. Spread over its land, that is 4.1 people to the square mile. Its largest town, Broken Bow, has 3,507 residents, 33.4% of the total. Together its 11 incorporated places hold 61.7% of those residents; the other 38.3% live outside any of them. Reported testing is thin here: 132 tests over 2008 to 2017, or 12.6 for every 1,000 residents (2025 estimate), where Nebraska as a whole comes to 21.2.

From Broken Bow to Comstock, CDC publishes no figure by town: each reads Custer County's.

The cities and towns in Custer County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Broken Bow3,507−0.4%33.4%
Arnold591+0.3%5.6%
Callaway561+0.4%5.3%
Sargent480−2.4%4.6%
Ansley456−0.7%4.3%
Merna344+0.3%3.3%
Mason City149+1.4%1.4%
Oconto141Level1.3%
Anselmo106−0.9%1.0%
Berwyn73Level0.7%
Comstock73Level0.7%

11 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).

Custer County, Homes

Homes in Custer County

Custer County is a place of houses on their own lots: 88% of its 5,331 homes are detached single-family houses, against 72% across Nebraska. The homes are older than Nebraska's as a whole: half were built before 1958 (1975 for Nebraska), and 52% date from before 1960. 71% of occupied homes are lived in by their owner (Nebraska: 67%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Custer County, Nebraska, 2019 to 2023
HomesCuster CountyNebraska
Housing units5,331855,631
Detached houses88%72%
In buildings of 5 or more6%17%
Mobile homes2%3%
Built before 196052%32%
Built since 200013%22%
Middle year built19581975
Owner-occupied71%67%

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