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Radon Levels in Bremer County, Iowa

EPA puts Bremer County in Zone 1, its highest radon zone, and high results are common there: 53.0% of the 957 radon tests reported to CDC (2008 to 2017, laboratory totals) 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

    53.0%

    5.5 pts below IA

    Bremer
    53.0%
    Iowa
    58.5%

    957 tests, 2008 to 2017

  • Median result

    4.3pCi/L

    Action level reached

    Bremer
    4.3 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    957

    22nd of 99 by tests

    Bremer
    957
    Polk
    10,945

    Reported to CDC before any fix, 2008 to 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 Iowa

    74 of 99

    Middle half

    Bremer
    53.0%
    Sioux
    84.2%

    By share, of 99 with 30+ tests

Read a result for Bremer County

Starts at Bremer County's median, 4.3 pCi/L

4.3pCi/L

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

EPA’s reading of 4.3 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. Bremer County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Bremer County, At a glance

Bremer County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Bremer 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 Bremer County, 2008 to 2017, laboratory

Reported results by concentration band, Bremer County, 2008 to 2017, laboratory
Under 2 pCi/L: 27%2 to 4 pCi/L: 20%4 pCi/L and above: 53%

Of 957 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Bremer County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L25827.0%
2 to 4 pCi/L19220.1%
4 pCi/L and above50753.0%
What these figures count

These are the 957 tests reported to CDC for Bremer County over 2008 to 2017 (laboratory totals), 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: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).

How to read these figures

Bremer County, Compared

Bremer County radon figures, compared

Calculated by Radon411

More than half: 53.0% of the 957 radon tests reported to CDC for Bremer County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 74th of 99 Iowa counties with 30 or more tests for the same period. That is 5.5 points below the 58.5% pooled from 99 Iowa counties.

The median result, 4.3 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 87.8 pCi/L. The rest split 27.0% under 2 pCi/L and 20.1% from 2 to 4 (Iowa: 21.8% and 19.7%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 53.0% share point the same way here.

4 of its 6 bordering counties with figures ran higher, led by Fayette County at 62.7%; Black Hawk County reported 48.4%. Statewide for the same period, Sioux County reported the highest share (84.2%) and Decatur County the lowest (25.9%).

CDC's ten-year totals for Bremer County went from 881 tests (2005 to 2014) to 957 (2008 to 2017), the share going from 55.8% to 53.0%.

Nationally, every county with a figure for the same period pools to 35.7%; Bremer County sits 17.3 points above it. CDC also counts 196 tests taken after mitigation in Bremer County for the same period: tests in homes where a fix was already in.

Bremer County against Iowa, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Bremer County
Bremer County95753.0%4.3 pCi/LThis county
Iowa, pooled99 counties, pooled95,24558.5%Not pooled+5.5 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−17.3 points
Sioux Countyhighest in the state1,98284.2%10.7 pCi/L+31.2 points
Decatur Countylowest in the state8525.9%2.5 pCi/L−27.1 points
Fayette County, IAborders it74662.7%5.6 pCi/L+9.7 points
Butler County, IAborders it37759.9%5.2 pCi/L+6.9 points
Floyd County, IAborders it69759.5%5.1 pCi/L+6.5 points
Chickasaw County, IAborders it49859.0%4.9 pCi/L+6.0 points
Buchanan County, IAborders it56451.2%4.1 pCi/L−1.8 points
Black Hawk County, IAborders it3,22348.4%3.8 pCi/L−4.6 points
Where Bremer County's reported results fell, 2008 to 2017, laboratory, beside Iowa and the United States
ResultBremer County testsBremer County shareIowa shareU.S. shareAgainst Iowa
Under 2 pCi/L25827.0%21.8%39.6%+5.2 points
2 to 4 pCi/L19220.1%19.7%24.7%+0.4 points
4 pCi/L and above50753.0%58.5%35.7%−5.5 points
Bremer County ranked among the 99 Iowa counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Chickasaw County69 of 9949859.0%4.9 pCi/L
Cerro Gordo County70 of 991,66259.0%4.8 pCi/L
Dallas County71 of 992,35258.5%4.9 pCi/L
Pottawattamie County72 of 991,86857.4%4.7 pCi/L
Washington County73 of 991,18654.9%4.6 pCi/L
Bremer County74 of 9995753.0%4.3 pCi/L
Jackson County75 of 991,05652.7%4.1 pCi/L
Clinton County76 of 991,37552.7%4.3 pCi/L
Louisa County77 of 999652.1%4.1 pCi/L
Buchanan County78 of 9956451.2%4.1 pCi/L
Des Moines County79 of 9943651.1%4.2 pCi/L
Bremer County ten-year laboratory totals, against Iowa's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIowa, pooledChange from the row before
2008 to 201795753.0%4.3 pCi/L87.8 pCi/L58.5%−1.0 points
2007 to 201691154.0%4.4 pCi/L87.8 pCi/L58.6%−1.6 points
2006 to 201592655.6%4.7 pCi/L87.8 pCi/L59.4%−0.2 points
2005 to 201488155.8%4.6 pCi/L87.8 pCi/L59.6%First on file

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

Bremer County, Geology

The ground under Bremer County

Predicted

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

USGS's geologic areas under Bremer County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Iowan SurfacePre-Illinoian glaical deposits and loess.High12100%

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

Bremer County beside the ground around it

On high-potential ground Bremer County is close to Iowa as a whole: 100% of its land against 98.8%. Of the 6 counties that border it, none has as large a share of high-potential ground; Black Hawk County comes nearest at 100%.

Share of land by USGS radon potential: Bremer County, the 6 counties bordering it and Iowa
AreaEPA zoneLow potentialModerate potentialHigh potential
Bremer CountyZone 1NoneNone100%
Chickasaw CountyZone 1NoneNone100%
Black Hawk CountyZone 1NoneNone100%
Butler CountyZone 1NoneNone100%
Fayette CountyZone 1NoneNone100%
Buchanan CountyZone 1NoneNone100%
Floyd CountyZone 1NoneNone100%
Iowa99 counties, pooled by land areaVariesNone1.2%98.8%

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

Local help

Bremer County, Local resources

Radon testing and mitigation in Bremer County

Listed radon businesses with an address in Bremer County:

Listed radon professionals by town: Waverly, Denver

What Iowa's program says
Phone
(515) 281-4928
Licensing of radon professionals
Iowa’s radon program approves applications for persons who wish to become certified to perform radon testing or credentialed to perform mitigation and laboratories that provide radon testing devices and analytical services.
Disclosure when a home is sold or rented
However, per Iowa Code chapters 543B.9 and 543B.18 and Iowa Administrative Code 193E Chapter 14 administered by the Iowa Real Estate Commission, a seller must disclose any known tests for the presence of radon and if yes, provide the date of last report and the result(s).

What it means

Bremer County, Questions

Questions about radon in Bremer County

Are radon levels high in Bremer County?

Over the 2008 to 2017 laboratory totals, 53.0% of the radon tests reported to CDC for Bremer County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.3 pCi/L. Of 99 Iowa counties with 30 or more tests for the same period, 73 reported a higher share; pooled, the state comes to 58.5%.

Which counties border Bremer County?

Bremer County borders 6 counties: Chickasaw County, Black Hawk County, Butler County, Fayette County, Buchanan County and Floyd County.

Products

Bremer County, Products

Testing a home in Bremer County

In Bremer County, 53.0% of 957 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 58.5% pooled across Iowa. In Zone 1 the year-round level in Bremer 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

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

Explore

Bremer County, Bordering counties

Counties bordering Bremer County

Calculated by Radon411

Bremer County, Cities and towns

Cities and towns in Bremer County

The Census Bureau estimates 25,296 residents in Bremer County for July 1, 2025, 282 more than in 2020 (+1.1%). That works out to 58 people per square mile of land. Its largest town, Waverly, has 10,561 residents, 41.7% of the total. CDC's 957 reported tests for 2008 to 2017 work out to 37.8 per 1,000 residents (2025 estimate), close to Iowa's 29.4.

From Waverly to Frederika, CDC publishes no figure by town: each reads Bremer County's.

The cities and towns in Bremer County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Waverly10,561+1.4%41.7%
Sumnerextends beyond Bremer County2,022−0.3%Counted whole
Denver1,954+1.3%7.7%
Tripoli1,208+1.3%4.8%
Janesvilleextends beyond Bremer County1,052+1.3%Counted whole
Readlyn860+1.2%3.4%
Plainfield394Level1.6%
Frederika207+1.5%0.8%

8 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 Bremer County is counted whole, so it has no share.

Bremer County, Homes

Homes in Bremer County

Bremer County is a place of houses on their own lots: 80% of its 10,542 homes are detached single-family houses, against 72% across Iowa. Half of its homes were built before 1969, close to Iowa's 1971: 41% date from before 1960 and 18% from 2000 or later. Owners live in 81% of the occupied homes (Iowa: 72%), so for most households a test and a fix are their own to order.

Homes in Bremer County, Iowa, 2019 to 2023
HomesBremer CountyIowa
Housing units10,5421,427,175
Detached houses80%72%
In buildings of 5 or more9%14%
Mobile homes2%3%
Built before 196041%39%
Built since 200018%21%
Middle year built19691971
Owner-occupied81%72%

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