Is radon high in Iowa?

Iowa's population-weighted predicted basement average is 3.5 pCi/L, about 1.9× the US average of 1.8. 50 of its 99 modeled counties are predicted at or above the EPA action level of 4 pCi/L, 49 are in the 2-4 "consider fixing" range and 0 are below 2. 41% of Iowa ZIP codes are predicted at 4 or higher.

Which Iowa county has the highest radon?

Sioux County has the highest predicted basement average in Iowa at 6.3 pCi/L (EPA Zone 1). The lowest is Scott County at 2.1 pCi/L. These are area figures; individual homes in any county can test far higher.

How many EPA Zone 1 counties are in Iowa?

99 of Iowa's 99 counties (100%) are EPA Zone 1 (highest potential), 0 are Zone 2 and 0 are Zone 3. The EPA zone map dates from 1993; the predicted values on this page come from a 2001-2021 model built on millions of actual tests, so the two can disagree for a given county.

Should I test for radon in Iowa?

Yes - with some urgency. Iowa's predicted average is in the moderate range, and 98.9% of its ZIP codes are predicted at 2 pCi/L or higher. A short-term charcoal kit or a continuous digital monitor will tell you your actual level within days.

Radon levels in Iowa: Moderate

Name: Radon levels by county for Iowa
Creator: RadonGrade
License: https://creativecommons.org/licenses/by/4.0/

The model predicts a population-weighted basement average of 3.5 pCi/L (model estimate) across Iowa's 99 counties - about 1.9× the US average of 1.8 pCi/L. Above-ground floors average 2.1 pCi/L.

Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. How the numbers work.

99 / 99

EPA Zone 1 counties (100%)

0 / 0

Zone 2 / Zone 3 counties

counties predicted ≥ 4 pCi/L

41%

of ZIP codes predicted ≥ 4 pCi/L

Test Iowa - the EPA says "consider fixing" in this range

The predicted basement average here is 3.5 pCi/L, in the 2-4 pCi/L band where the EPA recommends considering mitigation. Plenty of individual homes in a moderate area test above 4. Start with a short-term test; if it comes back at 2 or higher, follow up with a long-term test or a continuous monitor.

Get a short-term test kit →Or track it with a continuous monitor

Monitor link goes to the Airthings store - use code RADONGRADE-10OFF at checkout for 10% off any Airthings monitor.

Already tested at 4 pCi/L or higher? Find a certified mitigation professional (EPA). A mitigation system typically runs $800-$2,500 installed.

Affiliate links: we may earn a commission from Airthings or Amazon at no extra cost to you.

What the data says about radon in Iowa

According to the EPA zone map, 99 of Iowa's 99 counties are EPA Zone 1 (100%), 0 are Zone 2 and 0 are Zone 3. Every county in the state is in the highest-potential zone, which the EPA defines as a predicted average indoor screening level above 4 pCi/L. Treat the map as a coarse prior: it predates two decades of test data and never replaces a test in your own home.

The 2001-2021 national model predicts a population-weighted basement average of 3.5 pCi/L for Iowa (moderate range, 1.9× the US population-weighted average of 1.8). Of the 99 counties with predictions, 50 are predicted at or above 4 pCi/L, 49 in the 2-4 band and 0 below 2. The highest predicted county is Sioux County at 6.3 pCi/L; the lowest is Scott County at 2.1 - a 4.2 pCi/L spread that means a statewide average tells you little about any one county.

98.9% of the state's modeled ZIP codes are predicted at or above 2 pCi/L, and 41% at or above the 4 pCi/L action level - above the national shares of 4.2% and 48.7%. With more than half of ZIPs above 2, a test is worth doing before any purchase or renovation here.

Iowa counties by predicted radon

Sorted highest to lowest predicted basement average (model estimate). 99 counties.

County	Predicted basement	Upstairs	Grade	EPA zone	ZIPs
Sioux County	6.3 pCi/L	3.1	High	EPA Zone 1	12
Shelby County	6.1 pCi/L	3.5	High	EPA Zone 1	9
Cherokee County	6.0 pCi/L	3.0	High	EPA Zone 1	8
Ida County	6.0 pCi/L	3.1	High	EPA Zone 1	6
Plymouth County	5.9 pCi/L	3.2	High	EPA Zone 1	9
O'Brien County	5.9 pCi/L	3.3	High	EPA Zone 1	8
Audubon County	5.9 pCi/L	3.0	High	EPA Zone 1	5
Buena Vista County	5.5 pCi/L	2.9	High	EPA Zone 1	7
Lyon County	5.5 pCi/L	2.9	High	EPA Zone 1	7
Crawford County	5.4 pCi/L	2.9	High	EPA Zone 1	10
Cass County	5.4 pCi/L	2.9	High	EPA Zone 1	8
Page County	5.2 pCi/L	2.8	High	EPA Zone 1	9
Montgomery County	5.2 pCi/L	2.7	High	EPA Zone 1	6
Carroll County	5.1 pCi/L	2.7	High	EPA Zone 1	7
Clay County	5.1 pCi/L	2.8	High	EPA Zone 1	8
Sac County	5.1 pCi/L	2.8	High	EPA Zone 1	8
Osceola County	5.1 pCi/L	2.8	High	EPA Zone 1	5
Jasper County	4.9 pCi/L	2.7	High	EPA Zone 1	10
Adams County	4.9 pCi/L	2.7	High	EPA Zone 1	4
Adair County	4.9 pCi/L	2.6	High	EPA Zone 1	5
Calhoun County	4.9 pCi/L	2.7	High	EPA Zone 1	9
Monona County	4.8 pCi/L	2.5	High	EPA Zone 1	9
Marshall County	4.7 pCi/L	2.6	High	EPA Zone 1	12
Dickinson County	4.5 pCi/L	2.5	High	EPA Zone 1	7
Harrison County	4.5 pCi/L	2.3	High	EPA Zone 1	10
Taylor County	4.5 pCi/L	2.5	High	EPA Zone 1	7
Pocahontas County	4.5 pCi/L	2.5	High	EPA Zone 1	7
Guthrie County	4.5 pCi/L	2.6	High	EPA Zone 1	10
Mills County	4.4 pCi/L	2.5	High	EPA Zone 1	7
Emmet County	4.4 pCi/L	2.6	High	EPA Zone 1	5
Greene County	4.4 pCi/L	2.7	High	EPA Zone 1	7
Boone County	4.4 pCi/L	2.7	High	EPA Zone 1	5
Woodbury County	4.4 pCi/L	2.3	High	EPA Zone 1	19
Fremont County	4.3 pCi/L	2.4	High	EPA Zone 1	9
Webster County	4.3 pCi/L	2.5	High	EPA Zone 1	13
Humboldt County	4.3 pCi/L	2.6	High	EPA Zone 1	10
Allamakee County	4.2 pCi/L	2.7	High	EPA Zone 1	8
Union County	4.2 pCi/L	2.3	High	EPA Zone 1	5
Madison County	4.2 pCi/L	2.5	High	EPA Zone 1	11
Mitchell County	4.2 pCi/L	2.4	High	EPA Zone 1	6
Palo Alto County	4.2 pCi/L	2.5	High	EPA Zone 1	8
Kossuth County	4.1 pCi/L	2.5	High	EPA Zone 1	12
Poweshiek County	4.1 pCi/L	2.8	High	EPA Zone 1	8
Winneshiek County	4.1 pCi/L	2.9	High	EPA Zone 1	6
Franklin County	4.1 pCi/L	2.5	High	EPA Zone 1	7
Hamilton County	4.1 pCi/L	2.5	High	EPA Zone 1	9
Ringgold County	4.1 pCi/L	2.3	High	EPA Zone 1	7
Lucas County	4.1 pCi/L	2.3	High	EPA Zone 1	5
Monroe County	4.0 pCi/L	2.4	High	EPA Zone 1	3
Wright County	4.0 pCi/L	2.5	High	EPA Zone 1	8
Hardin County	4.0 pCi/L	2.5	Moderate	EPA Zone 1	8
Marion County	4.0 pCi/L	2.5	Moderate	EPA Zone 1	12
Warren County	3.9 pCi/L	2.6	Moderate	EPA Zone 1	10
Hancock County	3.9 pCi/L	2.3	Moderate	EPA Zone 1	9
Tama County	3.9 pCi/L	2.2	Moderate	EPA Zone 1	11
Howard County	3.8 pCi/L	2.4	Moderate	EPA Zone 1	5
Keokuk County	3.8 pCi/L	2.2	Moderate	EPA Zone 1	11
Winnebago County	3.8 pCi/L	2.4	Moderate	EPA Zone 1	6
Clarke County	3.8 pCi/L	2.2	Moderate	EPA Zone 1	4
Grundy County	3.7 pCi/L	2.2	Moderate	EPA Zone 1	7
Wayne County	3.7 pCi/L	2.0	Moderate	EPA Zone 1	7
Clayton County	3.6 pCi/L	2.3	Moderate	EPA Zone 1	15
Washington County	3.6 pCi/L	2.2	Moderate	EPA Zone 1	7
Davis County	3.5 pCi/L	2.1	Moderate	EPA Zone 1	4
Iowa County	3.5 pCi/L	2.0	Moderate	EPA Zone 1	11
Floyd County	3.5 pCi/L	2.1	Moderate	EPA Zone 1	6
Chickasaw County	3.5 pCi/L	2.2	Moderate	EPA Zone 1	6
Decatur County	3.4 pCi/L	2.0	Moderate	EPA Zone 1	7
Benton County	3.4 pCi/L	2.0	Moderate	EPA Zone 1	16
Polk County	3.4 pCi/L	2.2	Moderate	EPA Zone 1	30
Cedar County	3.4 pCi/L	2.1	Moderate	EPA Zone 1	9
Delaware County	3.4 pCi/L	2.2	Moderate	EPA Zone 1	8
Jones County	3.4 pCi/L	2.2	Moderate	EPA Zone 1	9
Pottawattamie County	3.4 pCi/L	2.1	Moderate	EPA Zone 1	16
Butler County	3.4 pCi/L	2.1	Moderate	EPA Zone 1	9
Fayette County	3.4 pCi/L	2.1	Moderate	EPA Zone 1	13
Jackson County	3.3 pCi/L	2.2	Moderate	EPA Zone 1	10
Mahaska County	3.3 pCi/L	2.4	Moderate	EPA Zone 1	8
Buchanan County	3.2 pCi/L	1.8	Moderate	EPA Zone 1	10
Worth County	3.2 pCi/L	2.0	Moderate	EPA Zone 1	7
Louisa County	3.2 pCi/L	1.8	Moderate	EPA Zone 1	5
Clinton County	3.1 pCi/L	1.8	Moderate	EPA Zone 1	11
Henry County	3.1 pCi/L	2.0	Moderate	EPA Zone 1	6
Lee County	3.1 pCi/L	1.9	Moderate	EPA Zone 1	10
Cerro Gordo County	3.1 pCi/L	2.1	Moderate	EPA Zone 1	8
Des Moines County	3.1 pCi/L	1.9	Moderate	EPA Zone 1	8
Muscatine County	3.0 pCi/L	1.8	Moderate	EPA Zone 1	8
Story County	3.0 pCi/L	2.0	Moderate	EPA Zone 1	13
Dallas County	3.0 pCi/L	2.0	Moderate	EPA Zone 1	13
Van Buren County	2.9 pCi/L	1.8	Moderate	EPA Zone 1	9
Dubuque County	2.8 pCi/L	1.7	Moderate	EPA Zone 1	12
Appanoose County	2.7 pCi/L	1.8	Moderate	EPA Zone 1	9
Bremer County	2.7 pCi/L	2.0	Moderate	EPA Zone 1	7
Wapello County	2.7 pCi/L	1.7	Moderate	EPA Zone 1	7
Jefferson County	2.6 pCi/L	1.6	Moderate	EPA Zone 1	6
Johnson County	2.4 pCi/L	1.6	Moderate	EPA Zone 1	11
Linn County	2.2 pCi/L	1.5	Moderate	EPA Zone 1	21
Black Hawk County	2.2 pCi/L	1.6	Moderate	EPA Zone 1	11
Scott County	2.1 pCi/L	1.6	Moderate	EPA Zone 1	18

Radon levels in Iowa cities

The 12 most-populous Iowa places among the 1,000 largest US cities (Census incorporated places and CDPs), by population. City figures are ZIP-land-weighted means of the model's ZIP predictions (model estimate).

City	Population	Predicted basement	Upstairs	Grade	ZIPs ≥ 4
Des Moines	210,381	3.7 pCi/L	2.4	Moderate	23%
Cedar Rapids	135,958	2.1 pCi/L	1.5	Moderate	0%
Davenport	100,354	2.1 pCi/L	1.5	Moderate	0%
Sioux City	85,727	4.4 pCi/L	2.3	High	67%
Iowa City	75,678	2.2 pCi/L	1.5	Moderate	0%
Ankeny	74,458	2.6 pCi/L	1.5	Moderate	0%
West Des Moines	72,205	3.0 pCi/L	2.0	Moderate	0%
Waterloo	66,606	2.2 pCi/L	1.5	Moderate	0%
Ames	65,686	2.7 pCi/L	1.9	Moderate	0%
Council Bluffs	62,399	3.0 pCi/L	1.9	Moderate	0%
Dubuque	58,877	2.9 pCi/L	1.7	Moderate	0%
Urbandale	46,729	2.9 pCi/L	2.1	Moderate	0%

Highest-radon ZIP codes in Iowa

The 10 Iowa ZIP codes with the highest predicted basement average (model estimate), out of 884 modeled. A ZIP average is still an area figure - neighboring homes routinely test several pCi/L apart.

ZIP	County	Predicted basement	Upstairs	Grade
51250	Sioux County	7.3 pCi/L	3.3	High
51050	Plymouth County	7.0 pCi/L	3.7	High
51239	Sioux County	7.0 pCi/L	3.4	High
51041	Sioux County	6.8 pCi/L	3.5	High
51234	Sioux County	6.7 pCi/L	3.3	High
51025	Ida County	6.7 pCi/L	3.4	High
51537	Shelby County	6.6 pCi/L	3.9	High
51238	Sioux County	6.5 pCi/L	3.3	High
50025	Audubon County	6.5 pCi/L	3.3	High
51005	Cherokee County	6.5 pCi/L	3.2	High

Iowa radon questions

Is radon high in Iowa?: Iowa's population-weighted predicted basement average is 3.5 pCi/L, about 1.9× the US average of 1.8. 50 of its 99 modeled counties are predicted at or above the EPA action level of 4 pCi/L, 49 are in the 2-4 "consider fixing" range and 0 are below 2. 41% of Iowa ZIP codes are predicted at 4 or higher.
Which Iowa county has the highest radon?: Sioux County has the highest predicted basement average in Iowa at 6.3 pCi/L (EPA Zone 1). The lowest is Scott County at 2.1 pCi/L. These are area figures; individual homes in any county can test far higher.
How many EPA Zone 1 counties are in Iowa?: 99 of Iowa's 99 counties (100%) are EPA Zone 1 (highest potential), 0 are Zone 2 and 0 are Zone 3. The EPA zone map dates from 1993; the predicted values on this page come from a 2001-2021 model built on millions of actual tests, so the two can disagree for a given county.
Should I test for radon in Iowa?: Yes - with some urgency. Iowa's predicted average is in the moderate range, and 98.9% of its ZIP codes are predicted at 2 pCi/L or higher. A short-term charcoal kit or a continuous digital monitor will tell you your actual level within days.

Iowa radon program

State programs keep lists of certified testers and mitigators and sometimes run kit programs. We link only pages we could verify, and Iowa's program page did not respond when we checked, so start from the EPA state radon contacts page. Then read how to test and what mitigation costs.