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Radon Levels in Linn County, Iowa

EPA puts Linn County in Zone 1, its highest radon zone, and 39.7% of its 9,395 reported radon tests (2008 to 2017, laboratory totals) were 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

    39.7%

    18.8 pts below IA

    Linn
    39.7%
    Iowa
    58.5%

    9,395 tests, 2008 to 2017

  • Median result

    3.0pCi/L

    Below action level

    Linn
    3.0 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    9,395

    2nd of 99 by tests

    Linn
    9,395
    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

    91 of 99

    Lowest quarter

    Linn
    39.7%
    Sioux
    84.2%

    By share, of 99 with 30+ tests

Read a result for Linn County

Starts at Linn County's median, 3.0 pCi/L

3.0pCi/L

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

EPA’s reading of 3.0 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. Linn County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Linn County, At a glance

Linn County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

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

Reported results by concentration band, Linn County, 2008 to 2017, laboratory
Under 2 pCi/L: 34%2 to 4 pCi/L: 26%4 pCi/L and above: 40%

Of 9,395 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Linn County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L3,17233.8%
2 to 4 pCi/L2,49226.5%
4 pCi/L and above3,73139.7%
What these figures count

These are the 9,395 tests reported to CDC for Linn 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

Linn County, Compared

Linn County radon figures, compared

Calculated by Radon411

In Linn County, about 4 in 10 reported tests over the 2008 to 2017 laboratory totals (3,731 of 9,395) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 4.0 points higher. Across 99 Iowa counties pooled together, 58.5% of tests reached that level, so Linn County runs 18.8 points below its state.

Of 7 neighbours with a figure, all 7 reported a larger share at or above 4 pCi/L; the spread is 41.6% (Johnson County) to 62.1% (Benton County). By share, Linn County is 91st of 99 Iowa counties with 30 or more tests for the same period.

Half the tests came in under 3.0 pCi/L and half over it; the single highest reached 132.3 pCi/L. Below the action level, 3,172 tests (33.8%) came in under 2 pCi/L, against 21.8% statewide, and 2,492 tests (26.5%) fell between 2 and 4, against 19.7% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 39.7% share point the same way here. USGS geology rates 100% of the county's land high radon potential. CDC also counts 1,103 tests taken after mitigation in Linn County for the same period: tests in homes where a fix was already in.

CDC's ten-year totals for Linn County went from 8,574 tests (2005 to 2014) to 9,395 (2008 to 2017), the share going from 43.2% to 39.7%.

Linn County against Iowa, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Linn County
Linn County9,39539.7%3.0 pCi/LThis county
Iowa, pooled99 counties, pooled95,24558.5%Not pooled+18.8 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−4.0 points
Sioux Countyhighest in the state1,98284.2%10.7 pCi/L+44.5 points
Decatur Countylowest in the state8525.9%2.5 pCi/L−13.8 points
Benton County, IAborders it69662.1%5.6 pCi/L+22.4 points
Cedar County, IAborders it76560.4%5.0 pCi/L+20.7 points
Jones County, IAborders it55559.3%5.1 pCi/L+19.6 points
Iowa County, IAborders it51959.2%5.1 pCi/L+19.5 points
Buchanan County, IAborders it56451.2%4.1 pCi/L+11.5 points
Delaware County, IAborders it52050.0%4.0 pCi/L+10.3 points
Johnson County, IAborders it7,32141.6%3.2 pCi/L+1.9 points
Where Linn County's reported results fell, 2008 to 2017, laboratory, beside Iowa and the United States
ResultLinn County testsLinn County shareIowa shareU.S. shareAgainst Iowa
Under 2 pCi/L3,17233.8%21.8%39.6%+12.0 points
2 to 4 pCi/L2,49226.5%19.7%24.7%+6.8 points
4 pCi/L and above3,73139.7%58.5%35.7%−18.8 points
Linn 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
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
Monroe County95 of 995933.9%2.9 pCi/L
Jefferson County96 of 9984133.5%2.6 pCi/L
Linn County ten-year laboratory totals, against Iowa's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIowa, pooledChange from the row before
2008 to 20179,39539.7%3.0 pCi/L132.3 pCi/L58.5%−0.9 points
2007 to 20169,25440.6%3.1 pCi/L277.3 pCi/L58.6%−1.8 points
2006 to 20159,02242.4%3.2 pCi/L277.3 pCi/L59.4%−0.8 points
2005 to 20148,57443.2%3.3 pCi/L277.3 pCi/L59.6%First on file

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

Linn County, Geology

The ground under Linn County

Predicted

USGS's geologic map puts all of Linn County's mapped land in one class: high radon potential. The map puts 89.2% of Linn County in the area it calls Iowan Surface and 10.8% in Loess-Covered Drift Plains. USGS gives the first a radon index of 12 and the second 13, both in the high band (12 to 17).

USGS's geologic areas under Linn County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Iowan SurfacePre-Illinoian glaical deposits and loess.High1289.2%
Loess-Covered Drift PlainsPre-Illinoian and Illinoian glacial deposits, and loess.High1310.8%

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

Linn County beside the ground around it

On high-potential ground Linn County is close to Iowa as a whole: 100% of its land against 98.8%. Of the 7 counties that border it, none has as large a share of high-potential ground; Benton County comes nearest at 100%.

Share of land by USGS radon potential: Linn County, the 7 counties bordering it and Iowa
AreaEPA zoneLow potentialModerate potentialHigh potential
Linn CountyZone 1NoneNone100%
Benton CountyZone 1NoneNone100%
Jones CountyZone 1NoneNone100%
Johnson CountyZone 1NoneNone100%
Cedar CountyZone 1NoneNone100%
Delaware CountyZone 1NoneNone100%
Buchanan CountyZone 1NoneNone100%
Iowa CountyZone 1NoneNone100%
Iowa99 counties, pooled by land areaVariesNone1.2%98.8%

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

Local help

Linn County, Local resources

Radon testing and mitigation in Linn County

Listed radon businesses with an address in Linn County:

Listed radon professionals by town: Cedar Rapids, Marion, Hiawatha, Central City, Walker

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

Linn County, Questions

Questions about radon in Linn County

Are radon levels high in Linn County?

Over the 2008 to 2017 laboratory totals, 39.7% of the radon tests reported to CDC for Linn County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.0 pCi/L. Of 99 Iowa counties with 30 or more tests for the same period, 90 reported a higher share; pooled, the state comes to 58.5%.

Which counties border Linn County?

Linn County borders 7 counties: Benton County, Jones County, Johnson County, Cedar County, Delaware County, Buchanan County and Iowa County.

Products

Linn County, Products

Testing a home in Linn County

In Linn County, 39.7% of 9,395 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 Linn 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

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

Explore

Linn County, Bordering counties

Counties bordering Linn County

Calculated by Radon411

Linn County, Cities and towns

Cities and towns in Linn County

The Census Bureau estimates 232,028 residents in Linn County for July 1, 2025, 1,623 more than in 2020 (+0.7%). That works out to 324 people per square mile of land. Cedar Rapids alone is home to 137,935 of them, 59.4% of the total. CDC's 9,395 reported tests for 2008 to 2017 work out to 40.5 per 1,000 residents (2025 estimate), close to Iowa's 29.4.

From Cedar Rapids to Prairieburg, CDC publishes no figure by town: each reads Linn County's.

The 12 largest cities and towns in Linn County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Cedar Rapids137,935+0.1%59.4%
Marion42,732+2.8%18.4%
Hiawatha7,432+3.5%3.2%
Mount Vernon4,514−0.6%1.9%
Robins3,366+0.1%1.5%
Fairfax2,925+2.6%1.3%
Center Point2,572−0.3%1.1%
Ely2,366+1.0%1.0%
Lisbon2,239+0.4%1.0%
Palo1,551+9.9%0.7%
Walfordextends beyond Linn County1,359−0.4%Counted whole
Central City1,253−0.9%0.5%
  • Springville
  • Coggon
  • Alburnett
  • Walker
  • Bertram
  • Prairieburg

18 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Linn County is counted whole, so it has no share.

Linn County, Homes

Homes in Linn County

Of Linn County's 101,989 homes, 67% are detached houses, against 72% across Iowa; 19% are in buildings of five or more homes. Half of its homes were built before 1977, close to Iowa's 1971: 28% date from before 1960 and 26% from 2000 or later. 73% of occupied homes are lived in by their owner (Iowa: 72%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Linn County, Iowa, 2019 to 2023
HomesLinn CountyIowa
Housing units101,9891,427,175
Detached houses67%72%
In buildings of 5 or more19%14%
Mobile homes3%3%
Built before 196028%39%
Built since 200026%21%
Middle year built19771971
Owner-occupied73%72%

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