Long-term kit
RL416 long-term radon test kit, lab fee included
- Lab fee included
Method: Alpha track
In home: 90 days to 12 months
Locations and reports
Radon Levels in Calhoun County, Iowa
EPA puts Calhoun County in Zone 1, its highest radon zone, and high results are common there: 69.8% of the 507 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
Share at 4+ pCi/L
69.8%
11.3 pts above IA
- Calhoun
- 69.8%
- Iowa
- 58.5%
507 tests, 2008 to 2017
Median result
6.1pCi/L
Action level reached
- Calhoun
- 6.1 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
507
46th of 99 by tests
- Calhoun
- 507
- Polk
- 10,945
Reported to CDC before any fix, 2008 to 2017
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Iowa
32 of 99
Middle half
- Calhoun
- 69.8%
- Sioux
- 84.2%
By share, of 99 with 30+ tests
Read a result for Calhoun County
Starts at Calhoun County's median, 6.1 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 6.1 pCi/L
At or above 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 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. Calhoun County's median reported result, 2008 to 2017.
The data
Calhoun County, At a glance
Calhoun County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Calhoun County in
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 Calhoun County, 2008 to 2017, laboratory
Under 2 pCi/L: 12%2 to 4 pCi/L: 18%4 pCi/L and above: 70%
Of 507 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 60 | 11.8% |
| 2 to 4 pCi/L | 93 | 18.3% |
| 4 pCi/L and above | 354 | 69.8% |
What these figures count
These are the 507 tests reported to CDC for Calhoun 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).
Calhoun County, Compared
Calhoun County radon figures, compared
Calculated by Radon411More than half: 69.8% of the 507 radon tests reported to CDC for Calhoun County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 32nd of 99 Iowa counties with 30 or more tests for the same period. That is 11.3 points above the 58.5% pooled from 99 Iowa counties.
The median result, 6.1 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 93.4 pCi/L. The rest split 11.8% under 2 pCi/L and 18.3% from 2 to 4 (Iowa: 21.8% and 19.7%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 69.8% share point the same way here.
4 of its 6 bordering counties with figures ran higher, led by Carroll County at 77.6%; Pocahontas County reported 68.8%. 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 Calhoun County went from 399 tests (2005 to 2014) to 507 (2008 to 2017), the share going from 70.4% to 69.8%.
Nationally, every county with a figure for the same period pools to 35.7%; Calhoun County sits 34.1 points above it. CDC also counts 18 tests taken after mitigation in Calhoun County for the same period: tests in homes where a fix was already in.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Calhoun County, Geology
The ground under Calhoun County
PredictedUSGS's geologic map puts all of Calhoun County's mapped land in one class: high radon potential. All of it lies in the area the map calls Des Moines Lobe, to which USGS gives a radon index of 12, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Des Moines Lobe | Calcareous loamy till derived from shale, limestone, dolomite, sandstone. | High | 12 | 100% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Calhoun County beside the ground around it
On high-potential ground Calhoun 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; Carroll County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Calhoun County, Local resources
Radon testing and mitigation in Calhoun County
Listed radon businesses with an address in Calhoun County:
- Iowa HHS Radon ProgramIowa HHS Radon Program, run by Iowa Department of Health and Human Services, licenses or certifies radon professionals, offers free or discounted test kits and states the rule for disclosing radon when a home is sold, and answers questions about testing and mitigation in Iowa.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
You can reach the Hotline by calling 1-800-383-5992 to order low-cost radon test kits and find answers to your radon questions.
- Compare kits
- Professionals in Iowa185 professionals are listed in Iowa.
Listed radon professionals by town: Lake City
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
Calhoun County, Questions
Questions about radon in Calhoun County
Are radon levels high in Calhoun County?
Over the 2008 to 2017 laboratory totals, 69.8% of the radon tests reported to CDC for Calhoun County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 6.1 pCi/L. Of 99 Iowa counties with 30 or more tests for the same period, 31 reported a higher share; pooled, the state comes to 58.5%.
Which counties border Calhoun County?
Calhoun County borders 6 counties: Sac County, Webster County, Greene County, Carroll County, Pocahontas County and Buena Vista County.
Products
Calhoun County, Products
Testing a home in Calhoun County
In Calhoun County, 69.8% of 507 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 Calhoun 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
Monitor
Hello Radon C battery radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- Battery
- Screen
Method: Alpha spectrometry
First reading: Within 24 hours
Short-term kitFirst Alert
RD1 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 2 to 4 days
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Calhoun County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Calhoun County
Explore
Calhoun County, Bordering counties
Counties bordering Calhoun County
Calculated by Radon411- Radon levels in Carroll CountyEPA zone 1
77.6%at or above 4 pCi/L
Median 7.8 pCi/L · 594 tests · 7.8 points above Calhoun County
- Radon levels in Sac CountyEPA zone 1
76.6%at or above 4 pCi/L
Median 7.0 pCi/L · 491 tests · 6.8 points above Calhoun County
- Radon levels in Buena Vista CountyEPA zone 1
72.1%at or above 4 pCi/L
Median 6.9 pCi/L · 688 tests · 2.3 points above Calhoun County
- Radon levels in Greene CountyEPA zone 1
71.3%at or above 4 pCi/L
Median 6.2 pCi/L · 143 tests · 1.5 points above Calhoun County
- Radon levels in Webster CountyEPA zone 1
69.4%at or above 4 pCi/L
Median 6.5 pCi/L · 1,189 tests · 0.4 points below Calhoun County
- Radon levels in Pocahontas CountyEPA zone 1
68.8%at or above 4 pCi/L
Median 6.4 pCi/L · 417 tests · 1.0 points below Calhoun County
Calhoun County, Cities and towns
Cities and towns in Calhoun County
About 9,562 people live in Calhoun County by the Census Bureau's estimate for July 1, 2025, 333 fewer than in 2020 (−3.4%). That works out to 17 people per square mile of land. Its largest town, Rockwell City, has 2,133 residents, 22.3% of the total. Testing is reported here more often than across the state: CDC's 507 reported tests for 2008 to 2017 come to 53.0 for every 1,000 residents (2025 estimate), against 29.4 for Iowa.
From Rockwell City to Yetter, CDC publishes no figure by town: each reads Calhoun County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Rockwell City | 2,133 | −5.2% | 22.3% |
| Lake City | 1,640 | −4.8% | 17.2% |
| Manson | 1,617 | −4.9% | 16.9% |
| Pomeroy | 501 | −4.6% | 5.2% |
| Lohrville | 360 | −4.8% | 3.8% |
| Farnhamvilleextends beyond Calhoun County | 358 | −5.5% | Counted whole |
| Lyttonextends beyond Calhoun County | 270 | −3.9% | Counted whole |
| Somers | 119 | −5.6% | 1.2% |
| Knierim | 51 | −5.6% | 0.5% |
| Rinard | 35 | −5.4% | 0.4% |
| Jolley | 28 | Level | 0.3% |
| Yetter | 20 | −4.8% | 0.2% |
12 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 Calhoun County is counted whole, so it has no share.
Calhoun County, Homes
Homes in Calhoun County
Calhoun County is a place of houses on their own lots: 85% of its 4,794 homes are detached single-family houses, against 72% across Iowa. The homes are older than Iowa's as a whole: half were built before 1960 (1971 for Iowa), and 50% date from before 1960. 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 | Calhoun County | Iowa |
|---|---|---|
| Housing units | 4,794 | 1,427,175 |
| Detached houses | 85% | 72% |
| In buildings of 5 or more | 5% | 14% |
| Mobile homes | 3% | 3% |
| Built before 1960 | 50% | 39% |
| Built since 2000 | 7% | 21% |
| Middle year built | 1960 | 1971 |
| Owner-occupied | 81% | 72% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.