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Radon Levels in Cass County, Nebraska

EPA puts Cass County in Zone 1, its highest radon zone, and high results are common there: 68.5% of the 111 radon tests reported to CDC (2023) 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

    68.5%

    30.3 pts above NE

    Cass
    68.5%
    Nebraska
    38.2%

    111 tests, 2023

  • Median result

    5.5pCi/L

    Action level reached

    Cass
    5.5 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    111

    13th of 33 by tests

    Cass
    111
    Lancaster
    4,058

    Reported to CDC before any fix, 2023

  • 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 Nebraska

    9 of 33

    Middle half

    Cass
    68.5%
    Gage
    79.8%

    By share, of 33 with 30+ tests

Read a result for Cass County

Starts at Cass County's median, 5.5 pCi/L

5.5pCi/L

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

EPA’s reading of 5.5 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. Cass County's median reported result, 2023.

Interpret this readingWhat a fix costs

The data

Cass County, At a glance

Cass County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Cass 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 Cass County, 2023

Share of reported tests at or above 4 pCi/L, by year, Cass County
Share of reported tests at or above 4 pCi/L, by year, Cass County
YearShare of reported tests at or above 4 pCi/L
201457.9%
201555.6%
201646.7%
201760.5%
201863.3%
201955.6%
202062.3%
202158.0%
202265.3%
202368.5%

2023: 68.5%. Across these years the share ran from 46.7% to 68.5%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 111 tests reported to CDC for Cass County over 2023, 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: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).

How to read these figures

Cass County, Compared

Cass County radon figures, compared

Calculated by Radon411

More than half: 68.5% of the 111 radon tests reported to CDC for Cass County in 2023 read at least 4 pCi/L. That places it 9th of 33 Nebraska counties with 30 or more tests for the same period. That is 30.3 points above the 38.2% pooled from 86 Nebraska counties.

The median result, 5.5 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 44.1 pCi/L. The rest split 13.5% under 2 pCi/L and 18.0% from 2 to 4 (Nebraska: 39.2% and 22.6%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 68.5% share point the same way here.

1 of its 4 bordering counties with figures ran higher, led by Saunders County at 73.2%; Lancaster County reported 26.7%. Statewide for the same period, Gage County reported the highest share (79.8%) and Dakota County the lowest (3.1%).

The busiest year on file was 2016, with 1,299 tests reported; the quietest, 2022, had 72.

Over 10 years of annual figures the share rose 10.6 points, from 57.9% in 2014 to 68.5% in 2023; its peak was 68.5% in 2023. Nationally, every county with a figure for the same period pools to 33.4%; Cass County sits 35.1 points above it. CDC also counts 36 tests taken after mitigation in Cass 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, Cass County against Nebraska2014 to 2023, years with 30 or more tests: Cass County 57.9% to 68.5%, the state's pooled share 38.2% in 2023.
Cass CountyNebraska, pooled
Share of reported tests at or above 4 pCi/L by year, Cass County against Nebraska: data table
YearTestsCass County, at or above 4 pCi/LNebraska, pooled
201496357.9%50.5%
201596055.6%53.3%
20161,29946.7%47.4%
201791860.5%47.7%
201886763.3%44.5%
201964255.6%44.3%
202054962.3%42.2%
202141458.0%34.9%
20227265.3%34.0%
202311168.5%38.2%
Cass County against Nebraska, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Cass County
Cass County11168.5%5.5 pCi/LThis county
Nebraska, pooled86 counties, pooled11,16338.2%Not pooled−30.3 points
United States, pooled642 counties, pooled128,74033.4%Not pooled−35.1 points
Gage Countyhighest in the state8479.8%9.4 pCi/L+11.3 points
Dakota Countylowest in the state1303.1%0.4 pCi/L−65.4 points
Saunders County, NEborders it9773.2%6.2 pCi/L+4.7 points
Otoe County, NEborders it5964.4%5.7 pCi/L−4.1 points
Sarpy County, NEborders it75551.9%4.1 pCi/L−16.6 points
Lancaster County, NEborders it4,05826.7%1.6 pCi/L−41.8 points
Where Cass County's reported results fell, 2023, beside Nebraska and the United States
ResultCass County testsCass County shareNebraska shareU.S. shareAgainst Nebraska
Under 2 pCi/L1513.5%39.2%41.4%−25.7 points
2 to 4 pCi/L2018.0%22.6%25.2%−4.6 points
4 pCi/L and above7668.5%38.2%33.4%+30.3 points
Cass County ranked among the 33 Nebraska counties with 30 or more tests, by share at or above 4 pCi/L, 2023
CountyRankTestsAt or above 4 pCi/LMedian
Washington County4 of 337176.1%6.5 pCi/L
Wayne County5 of 334374.4%6.9 pCi/L
Saunders County6 of 339773.2%6.2 pCi/L
Cuming County7 of 333770.3%6.8 pCi/L
Stanton County8 of 333268.8%7.8 pCi/L
Cass County9 of 3311168.5%5.5 pCi/L
Madison County10 of 3321366.7%5.8 pCi/L
Adams County11 of 3315566.5%4.8 pCi/L
Phelps County12 of 334365.1%4.9 pCi/L
Hamilton County13 of 334864.6%5.0 pCi/L
York County14 of 336264.5%5.7 pCi/L
Cass County radon tests by year, against Nebraska's pooled share
YearTestsAt or above 4 pCi/LMedianHighestNebraska, pooledChange from the row before
202311168.5%5.5 pCi/L44.1 pCi/L38.2%+3.2 points
20227265.3%6.2 pCi/L28.5 pCi/L34.0%+7.3 points
202141458.0%5.0 pCi/L117.4 pCi/L34.9%−4.3 points
202054962.3%5.0 pCi/L37.2 pCi/L42.2%+6.7 points
201964255.6%4.8 pCi/L96.0 pCi/L44.3%−7.7 points
201886763.3%5.5 pCi/L95.2 pCi/L44.5%+2.8 points
201791860.5%5.5 pCi/L46.5 pCi/L47.7%+13.8 points
20161,29946.7%3.5 pCi/L166.0 pCi/L47.4%−8.9 points
201596055.6%4.6 pCi/L45.3 pCi/L53.3%−2.3 points
201496357.9%5.0 pCi/L38.2 pCi/L50.5%First on file

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

Cass County, Geology

The ground under Cass County

Predicted

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

USGS's geologic areas under Cass County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Pre-Wisconsin glacial depositsLoess-mantled glacial drift.High13100%

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

Cass County beside the ground around it

Cass County has more high-potential ground than Nebraska as a whole: 100% of its land against 40.9%. Of the 6 counties that border it, none has as large a share of high-potential ground; Fremont County, IA comes nearest at 100%.

Share of land by USGS radon potential: Cass County, the 6 counties bordering it and Nebraska
AreaEPA zoneLow potentialModerate potentialHigh potential
Cass CountyZone 1NoneNone100%
Sarpy CountyZone 1NoneNone100%
Otoe CountyZone 1NoneNone100%
Mills County, IAZone 1NoneNone100%
Lancaster CountyZone 1NoneNone100%
Fremont County, IAZone 1NoneNone100%
Saunders CountyZone 1NoneNone100%
Nebraska93 counties, pooled by land areaVaries28.2%30.9%40.9%

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

Local help

Cass County, Local resources

Radon testing and mitigation in Cass County

Listed radon businesses with an address in Cass County:

Listed radon professionals by town: Louisville

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

Cass County, Questions

Questions about radon in Cass County

Are radon levels high in Cass County?

In 2023, 68.5% of the radon tests reported to CDC for Cass County, Nebraska were at or above 4 pCi/L, and the median reported pre-mitigation result was 5.5 pCi/L. Of 33 Nebraska counties with 30 or more tests for the same period, 8 reported a higher share; pooled, the state comes to 38.2%.

Which counties border Cass County?

Cass County borders 6 counties: Sarpy County, NE, Otoe County, NE, Mills County, IA, Lancaster County, NE, Fremont County, IA and Saunders County, NE.

Products

Cass County, Products

Testing a home in Cass County

In Cass County, 68.5% of 111 tests reported to CDC in 2023 reached 4 pCi/L, against 38.2% pooled across Nebraska. In Zone 1 the year-round level in Cass 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

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

Explore

Cass County, Bordering counties

Counties bordering Cass County

Calculated by Radon411

Cass County, Cities and towns

Cities and towns in Cass County

The Census Bureau estimates 27,657 residents in Cass County for July 1, 2025, 1,047 more than in 2020 (+3.9%). That works out to 50 people per square mile of land. Its largest town, Plattsmouth, has 6,955 residents, 25.1% of the total. Together its 15 incorporated places hold 51.2% of those residents; the other 48.8% live outside any of them. CDC's 111 reported tests for 2023 work out to 4.0 per 1,000 residents (2025 estimate), close to Nebraska's 5.5.

From Plattsmouth to South Bend, CDC publishes no figure by town: each reads Cass County's.

The 12 largest cities and towns in Cass County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Plattsmouth6,955+5.5%25.1%
Louisville1,419+5.3%5.1%
Eagle1,206+10.5%4.4%
Weeping Water1,061+2.3%3.8%
Elmwood684+2.4%2.5%
Greenwood616+3.4%2.2%
Murray502+3.1%1.8%
Cedar Creek476+2.6%1.7%
Murdock276+2.6%1.0%
Union200+2.6%0.7%
Avoca187+2.7%0.7%
Nehawka178+2.3%0.6%
  • Manley
  • Alvo
  • South Bend

15 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).

Cass County, Homes

Homes in Cass County

Cass County is a place of houses on their own lots: 86% of its 11,780 homes are detached single-family houses, against 72% across Nebraska. Half of its homes were built before 1977, close to Nebraska's 1975: 28% date from before 1960 and 20% from 2000 or later. Owners live in 84% of the occupied homes (Nebraska: 67%), so for most households a test and a fix are their own to order.

Homes in Cass County, Nebraska, 2019 to 2023
HomesCass CountyNebraska
Housing units11,780855,631
Detached houses86%72%
In buildings of 5 or more4%17%
Mobile homes4%3%
Built before 196028%32%
Built since 200020%22%
Middle year built19771975
Owner-occupied84%67%

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