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 Cerro Gordo County, Iowa
EPA puts Cerro Gordo County in Zone 1, its highest radon zone, and high results are common there: 59.0% of the 1,662 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
59.0%
0.5 pts above IA
- Cerro Gordo
- 59.0%
- Iowa
- 58.5%
1,662 tests, 2008 to 2017
Median result
4.8pCi/L
Action level reached
- Cerro Gordo
- 4.8 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
1,662
12th of 99 by tests
- Cerro Gordo
- 1,662
- 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
70 of 99
Middle half
- Cerro Gordo
- 59.0%
- Sioux
- 84.2%
By share, of 99 with 30+ tests
Read a result for Cerro Gordo County
Starts at Cerro Gordo County's median, 4.8 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.8 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. Cerro Gordo County's median reported result, 2008 to 2017.
The data
Cerro Gordo County, At a glance
Cerro Gordo County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Cerro Gordo 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 Cerro Gordo County, 2008 to 2017, laboratory
Under 2 pCi/L: 20%2 to 4 pCi/L: 21%4 pCi/L and above: 59%
Of 1,662 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 330 | 19.9% |
| 2 to 4 pCi/L | 351 | 21.1% |
| 4 pCi/L and above | 981 | 59.0% |
What these figures count
These are the 1,662 tests reported to CDC for Cerro Gordo 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).
Cerro Gordo County, Compared
Cerro Gordo County radon figures, compared
Calculated by Radon411More than half: 59.0% of the 1,662 radon tests reported to CDC for Cerro Gordo County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 70th of 99 Iowa counties with 30 or more tests for the same period. That is 0.5 points above the 58.5% pooled from 99 Iowa counties.
The median result, 4.8 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 157.0 pCi/L. The rest split 19.9% under 2 pCi/L and 21.1% from 2 to 4 (Iowa: 21.8% and 19.7%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 59.0% share point the same way here.
All 8 of its bordering counties with figures ran higher, led by Franklin County at 73.5%; the lowest of them, Floyd County, reported 59.5%. 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 Cerro Gordo County went from 1,284 tests (2005 to 2014) to 1,662 (2008 to 2017), the share going from 59.9% to 59.0%.
Nationally, every county with a figure for the same period pools to 35.7%; Cerro Gordo County sits 23.3 points above it. CDC also counts 245 tests taken after mitigation in Cerro Gordo 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.
Cerro Gordo County, Geology
The ground under Cerro Gordo County
PredictedUSGS's geologic map puts all of Cerro Gordo County's mapped land in one class: high radon potential. The map puts 76.7% of Cerro Gordo County in the area it calls Iowan Surface and 23.3% in Des Moines Lobe. USGS gives both 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 |
|---|---|---|---|---|
| Iowan Surface | Pre-Illinoian glaical deposits and loess. | High | 12 | 76.7% |
| Des Moines Lobe | Calcareous loamy till derived from shale, limestone, dolomite, sandstone. | High | 12 | 23.3% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Cerro Gordo County beside the ground around it
On high-potential ground Cerro Gordo County is close to Iowa as a whole: 100% of its land against 98.8%. Of the 8 counties that border it, none has as large a share of high-potential ground; Butler County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Cerro Gordo County, Local resources
Radon testing and mitigation in Cerro Gordo County
Listed radon businesses with an address in Cerro Gordo 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: Mason City, Rockwell
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
Cerro Gordo County, Questions
Questions about radon in Cerro Gordo County
Are radon levels high in Cerro Gordo County?
Over the 2008 to 2017 laboratory totals, 59.0% of the radon tests reported to CDC for Cerro Gordo County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.8 pCi/L. Of 99 Iowa counties with 30 or more tests for the same period, 69 reported a higher share; pooled, the state comes to 58.5%.
Which counties border Cerro Gordo County?
Cerro Gordo County borders 8 counties: Worth County, Franklin County, Floyd County, Hancock County, Butler County, Wright County, Winnebago County and Mitchell County.
Products
Cerro Gordo County, Products
Testing a home in Cerro Gordo County
In Cerro Gordo County, 59.0% of 1,662 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 Cerro Gordo 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
View Radon Wi-Fi radon monitor with an e-paper display
- C-NRPP 2024/25: Approved
- Battery
- Wi-Fi, Bluetooth
- Screen, app
Method: Alpha spectrometry
Readings: Every 60 minutes
Short-term kit
Radon Short Term Test Kit short-term charcoal radon test kit, lab fee included
- Lab fee included
Method: Charcoal
In home: 2 to 7 days
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Cerro Gordo County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Cerro Gordo County
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Cerro Gordo County, Bordering counties
Counties bordering Cerro Gordo County
Calculated by Radon411- Radon levels in Franklin CountyEPA zone 1
73.5%at or above 4 pCi/L
Median 6.2 pCi/L · 313 tests · 14.5 points above Cerro Gordo County
- Radon levels in Winnebago CountyEPA zone 1
71.9%at or above 4 pCi/L
Median 6.7 pCi/L · 829 tests · 12.9 points above Cerro Gordo County
- Radon levels in Mitchell CountyEPA zone 1
70.7%at or above 4 pCi/L
Median 6.4 pCi/L · 444 tests · 11.7 points above Cerro Gordo County
- Radon levels in Worth CountyEPA zone 1
67.5%at or above 4 pCi/L
Median 6.0 pCi/L · 154 tests · 8.5 points above Cerro Gordo County
- Radon levels in Wright CountyEPA zone 1
66.8%at or above 4 pCi/L
Median 6.2 pCi/L · 292 tests · 7.8 points above Cerro Gordo County
- Radon levels in Hancock CountyEPA zone 1
64.5%at or above 4 pCi/L
Median 5.5 pCi/L · 640 tests · 5.5 points above Cerro Gordo County
- Radon levels in Butler CountyEPA zone 1
59.9%at or above 4 pCi/L
Median 5.2 pCi/L · 377 tests · 0.9 points above Cerro Gordo County
- Radon levels in Floyd CountyEPA zone 1
59.5%at or above 4 pCi/L
Median 5.1 pCi/L · 697 tests · 0.5 points above Cerro Gordo County
Cerro Gordo County, Cities and towns
Cities and towns in Cerro Gordo County
About 42,372 people live in Cerro Gordo County by the Census Bureau's estimate for July 1, 2025, 646 fewer than in 2020 (−1.5%). That works out to 75 people per square mile of land. Mason City alone is home to 26,853 of them, 63.4% of the total. CDC's 1,662 reported tests for 2008 to 2017 work out to 39.2 per 1,000 residents (2025 estimate), close to Iowa's 29.4.
From Mason City to Dougherty, CDC publishes no figure by town: each reads Cerro Gordo County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Mason City | 26,853 | −1.6% | 63.4% |
| Clear Lake | 7,601 | −0.8% | 17.9% |
| Nora Springsextends beyond Cerro Gordo County | 1,316 | −3.6% | Counted whole |
| Rockwell | 1,039 | −2.7% | 2.5% |
| Ventura | 698 | −1.8% | 1.6% |
| Thornton | 391 | −3.2% | 0.9% |
| Plymouth | 366 | −3.9% | 0.9% |
| Meservey | 211 | −3.7% | 0.5% |
| Rock Falls | 143 | −4.7% | 0.3% |
| Swaledale | 137 | −4.2% | 0.3% |
| Dougherty | 58 | −3.3% | 0.1% |
11 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 Cerro Gordo County is counted whole, so it has no share.
Cerro Gordo County, Homes
Homes in Cerro Gordo County
Cerro Gordo County is a place of houses on their own lots: 75% of its 22,730 homes are detached single-family houses, against 72% across Iowa. The homes are older than Iowa's as a whole: half were built before 1959 (1971 for Iowa), and 52% date from before 1960. 72% 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 | Cerro Gordo County | Iowa |
|---|---|---|
| Housing units | 22,730 | 1,427,175 |
| Detached houses | 75% | 72% |
| In buildings of 5 or more | 13% | 14% |
| Mobile homes | 4% | 3% |
| Built before 1960 | 52% | 39% |
| Built since 2000 | 12% | 21% |
| Middle year built | 1959 | 1971 |
| Owner-occupied | 72% | 72% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.