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Radon Levels in Davis County, Iowa

EPA puts Davis County in Zone 1, its highest radon zone, and high results are common there: 42.4% of the 85 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

    42.4%

    16.1 pts below IA

    Davis
    42.4%
    Iowa
    58.5%

    85 tests, 2008 to 2017

  • Median result

    3.1pCi/L

    Below action level

    Davis
    3.1 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    85

    93rd of 99 by tests

    Davis
    85
    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

    89 of 99

    Lowest quarter

    Davis
    42.4%
    Sioux
    84.2%

    By share, of 99 with 30+ tests

Read a result for Davis County

Starts at Davis County's median, 3.1 pCi/L

3.1pCi/L

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

EPA’s reading of 3.1 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. Davis County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Davis County, At a glance

Davis County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Davis 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 57% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Davis County, 2008 to 2017, laboratory

Reported results by concentration band, Davis County, 2008 to 2017, laboratory
Under 2 pCi/L: 31%2 to 4 pCi/L: 27%4 pCi/L and above: 42%

Of 85 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Davis County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L2630.6%
2 to 4 pCi/L2327.1%
4 pCi/L and above3642.4%
What these figures count

These are the 85 tests reported to CDC for Davis 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

Davis County, Compared

Davis County radon figures, compared

Calculated by Radon411

In Davis County, about 4 in 10 reported tests over the 2008 to 2017 laboratory totals (36 of 85) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 6.7 points higher. Across 99 Iowa counties pooled together, 58.5% of tests reached that level, so Davis County runs 16.1 points below its state.

Of 5 neighbours with a figure, 1 reported a larger share at or above 4 pCi/L and 4 a smaller one; the spread is 32.1% (Van Buren County) to 45.3% (Appanoose County). By share, Davis County is 89th of 99 Iowa counties with 30 or more tests for the same period.

Half the tests came in under 3.1 pCi/L and half over it; the single highest reached 31.1 pCi/L. Below the action level, 26 tests (30.6%) came in under 2 pCi/L, against 21.8% statewide, and 23 tests (27.1%) fell between 2 and 4, against 19.7% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 42.4% share point the same way here. USGS geology rates 57% of the county's land high radon potential.

CDC's ten-year totals for Davis County went from 83 tests (2005 to 2014) to 85 (2008 to 2017), the share going from 42.2% to 42.4%.

Davis County against Iowa, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Davis County
Davis County8542.4%3.1 pCi/LThis county
Iowa, pooled99 counties, pooled95,24558.5%Not pooled+16.1 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−6.7 points
Sioux Countyhighest in the state1,98284.2%10.7 pCi/L+41.8 points
Decatur Countylowest in the state8525.9%2.5 pCi/L−16.5 points
Appanoose County, IAborders it11745.3%3.7 pCi/L+2.9 points
Wapello County, IAborders it28735.9%2.7 pCi/L−6.5 points
Monroe County, IAborders it5933.9%2.9 pCi/L−8.5 points
Jefferson County, IAborders it84133.5%2.6 pCi/L−8.9 points
Van Buren County, IAborders it5632.1%2.3 pCi/L−10.3 points
Scotland County, MOborders it1816.7%1.4 pCi/L−25.7 points
Schuyler County, MOborders it119.1%1.0 pCi/L−33.3 points
Where Davis County's reported results fell, 2008 to 2017, laboratory, beside Iowa and the United States
ResultDavis County testsDavis County shareIowa shareU.S. shareAgainst Iowa
Under 2 pCi/L2630.6%21.8%39.6%+8.8 points
2 to 4 pCi/L2327.1%19.7%24.7%+7.4 points
4 pCi/L and above3642.4%58.5%35.7%−16.1 points
Davis 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
Henry County84 of 9916846.4%3.4 pCi/L
Clarke County85 of 9912045.8%3.5 pCi/L
Appanoose County86 of 9911745.3%3.7 pCi/L
Scott County87 of 993,52044.3%3.3 pCi/L
Lee County88 of 9935143.6%3.2 pCi/L
Davis County89 of 998542.4%3.1 pCi/L
Johnson County90 of 997,32141.6%3.2 pCi/L
Linn County91 of 999,39539.7%3.0 pCi/L
Lucas County92 of 998439.3%3.3 pCi/L
Wapello County93 of 9928735.9%2.7 pCi/L
Wayne County94 of 994634.8%3.0 pCi/L
Davis County ten-year laboratory totals, against Iowa's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIowa, pooledChange from the row before
2008 to 20178542.4%3.1 pCi/L31.1 pCi/L58.5%+1.2 points
2007 to 20168541.2%2.7 pCi/L31.1 pCi/L58.6%−4.7 points
2006 to 20158545.9%3.4 pCi/L31.1 pCi/L59.4%+3.7 points
2005 to 20148342.2%3.1 pCi/L31.1 pCi/L59.6%First on file

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

Davis County, Geology

The ground under Davis County

Predicted

USGS's geologic map splits Davis County: 57.1% of its land is high radon potential and 42.9% moderate. The map puts 57.1% of Davis County in the area it calls Loess-Covered Drift Plains and 42.9% in Dissected Till Plains. USGS gives the first a radon index of 13, in the high band (12 to 17), and the second 11, in the moderate band (9 to 11).

USGS's geologic areas under Davis County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Loess-Covered Drift PlainsPre-Illinoian and Illinoian glacial deposits, and loess.High1357.1%
Dissected Till PlainsTill-covered Pennsylvanian sandstone, shale, and limestone.Moderate1142.9%

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

Davis County beside the ground around it

Iowa as a whole has more high-potential ground than Davis County: 98.8% of its land, against 57.1% here. Of the 7 counties that border it, 4 have more high-potential ground, Jefferson County the most at 100%.

Share of land by USGS radon potential: Davis County, the 7 counties bordering it and Iowa
AreaEPA zoneLow potentialModerate potentialHigh potential
Davis CountyZone 1None42.9%57.1%
Wapello CountyZone 1NoneNone100%
Schuyler County, MOZone 2None100%None
Scotland County, MOZone 2None100%None
Appanoose CountyZone 1None46.5%53.5%
Van Buren CountyZone 1None8.8%91.2%
Monroe CountyZone 1NoneNone100%
Jefferson CountyZone 1NoneNone100%
Iowa99 counties, pooled by land areaVariesNone1.2%98.8%

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

Local help

Davis County, Local resources

Radon testing and mitigation in Davis County

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

Davis County, Questions

Questions about radon in Davis County

Are radon levels high in Davis County?

Over the 2008 to 2017 laboratory totals, 42.4% of the radon tests reported to CDC for Davis County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.1 pCi/L. Of 99 Iowa counties with 30 or more tests for the same period, 88 reported a higher share; pooled, the state comes to 58.5%.

Which counties border Davis County?

Davis County borders 7 counties: Wapello County, IA, Schuyler County, MO, Scotland County, MO, Appanoose County, IA, Van Buren County, IA, Monroe County, IA and Jefferson County, IA.

Products

Davis County, Products

Testing a home in Davis County

In Davis County, 42.4% of 85 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 Davis 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

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

Explore

Davis County, Bordering counties

Counties bordering Davis County

Calculated by Radon411

Davis County, Cities and towns

Cities and towns in Davis County

The Census Bureau estimates 9,230 residents in Davis County for July 1, 2025, 114 more than in 2020 (+1.3%). That works out to 18 people per square mile of land. Its largest town, Bloomfield, has 2,785 residents, 30.2% of the total. Together its 4 incorporated places hold 36.2% of those residents; the other 63.8% live outside any of them. Reported testing is thin here: 85 tests over 2008 to 2017, or 9.2 for every 1,000 residents (2025 estimate), where Iowa as a whole comes to 29.4.

From Bloomfield to Floris, CDC publishes no figure by town: each reads Davis County's.

The cities and towns in Davis County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Bloomfield2,785+3.9%30.2%
Pulaski264Level2.9%
Drakesville172+5.5%1.9%
Floris118Level1.3%

4 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).

Davis County, Homes

Homes in Davis County

Davis County is a place of houses on their own lots: 86% of its 3,602 homes are detached single-family houses, against 72% across Iowa. Half of its homes were built before 1973, close to Iowa's 1971: 39% date from before 1960 and 16% from 2000 or later. Owners live in 84% of the occupied homes (Iowa: 72%), so for most households a test and a fix are their own to order.

Homes in Davis County, Iowa, 2019 to 2023
HomesDavis CountyIowa
Housing units3,6021,427,175
Detached houses86%72%
In buildings of 5 or more3%14%
Mobile homes8%3%
Built before 196039%39%
Built since 200016%21%
Middle year built19731971
Owner-occupied84%72%

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