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 Mahaska County, Iowa
EPA puts Mahaska County in Zone 1, its highest radon zone, and high results are common there: 61.1% of the 288 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
61.1%
2.6 pts above IA
- Mahaska
- 61.1%
- Iowa
- 58.5%
288 tests, 2008 to 2017
Median result
5.2pCi/L
Action level reached
- Mahaska
- 5.2 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
288
73rd of 99 by tests
- Mahaska
- 288
- 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
60 of 99
Middle half
- Mahaska
- 61.1%
- Sioux
- 84.2%
By share, of 99 with 30+ tests
Read a result for Mahaska County
Starts at Mahaska County's median, 5.2 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 5.2 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. Mahaska County's median reported result, 2008 to 2017.
The data
Mahaska County, At a glance
Mahaska County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Mahaska 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 Mahaska County, 2008 to 2017, laboratory
Under 2 pCi/L: 21%2 to 4 pCi/L: 18%4 pCi/L and above: 61%
Of 288 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 59 | 20.5% |
| 2 to 4 pCi/L | 53 | 18.4% |
| 4 pCi/L and above | 176 | 61.1% |
What these figures count
These are the 288 tests reported to CDC for Mahaska 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).
Mahaska County, Compared
Mahaska County radon figures, compared
Calculated by Radon411More than half: 61.1% of the 288 radon tests reported to CDC for Mahaska County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 60th of 99 Iowa counties with 30 or more tests for the same period. That is 2.6 points above the 58.5% pooled from 99 Iowa counties.
The median result, 5.2 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 53.3 pCi/L. The rest split 20.5% under 2 pCi/L and 18.4% from 2 to 4 (Iowa: 21.8% and 19.7%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 61.1% share point the same way here.
3 of its 6 bordering counties with figures ran higher, led by Jasper County at 73.3%; Monroe County reported 33.9%. 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 Mahaska County went from 309 tests (2005 to 2014) to 288 (2008 to 2017), the share going from 54.7% to 61.1%.
Nationally, every county with a figure for the same period pools to 35.7%; Mahaska County sits 25.4 points above it. CDC also counts 31 tests taken after mitigation in Mahaska 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.
Mahaska County, Geology
The ground under Mahaska County
PredictedUSGS's geologic map puts all of Mahaska County's mapped land in one class: high radon potential. All of it lies in the area the map calls Loess-Covered Drift Plains, to which USGS gives a radon index of 13, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Loess-Covered Drift Plains | Pre-Illinoian and Illinoian glacial deposits, and loess. | High | 13 | 100% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Mahaska County beside the ground around it
On high-potential ground Mahaska 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; Keokuk County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Mahaska County, Local resources
Radon testing and mitigation in Mahaska County
Listed radon businesses with an address in Mahaska 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: Pella, Fremont
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
Mahaska County, Questions
Questions about radon in Mahaska County
Are radon levels high in Mahaska County?
Over the 2008 to 2017 laboratory totals, 61.1% of the radon tests reported to CDC for Mahaska County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 5.2 pCi/L. Of 99 Iowa counties with 30 or more tests for the same period, 59 reported a higher share; pooled, the state comes to 58.5%.
Which counties border Mahaska County?
Mahaska County borders 6 counties: Marion County, Keokuk County, Monroe County, Wapello County, Poweshiek County and Jasper County.
Products
Mahaska County, Products
Testing a home in Mahaska County
In Mahaska County, 61.1% of 288 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 Mahaska 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
Mahaska County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Mahaska County
Explore
Mahaska County, Bordering counties
Counties bordering Mahaska County
Calculated by Radon411- Radon levels in Jasper CountyEPA zone 1
73.3%at or above 4 pCi/L
Median 8.2 pCi/L · 746 tests · 12.2 points above Mahaska County
- Radon levels in Poweshiek CountyEPA zone 1
70.6%at or above 4 pCi/L
Median 7.2 pCi/L · 419 tests · 9.5 points above Mahaska County
- Radon levels in Marion CountyEPA zone 1
67.3%at or above 4 pCi/L
Median 6.0 pCi/L · 1,151 tests · 6.2 points above Mahaska County
- Radon levels in Keokuk CountyEPA zone 1
60.3%at or above 4 pCi/L
Median 5.2 pCi/L · 214 tests · 0.8 points below Mahaska County
- Radon levels in Wapello CountyEPA zone 1
35.9%at or above 4 pCi/L
Median 2.7 pCi/L · 287 tests · 25.2 points below Mahaska County
- Radon levels in Monroe CountyEPA zone 1
33.9%at or above 4 pCi/L
Median 2.9 pCi/L · 59 tests · 27.2 points below Mahaska County
Mahaska County, Cities and towns
Cities and towns in Mahaska County
About 21,880 people live in Mahaska County by the Census Bureau's estimate for July 1, 2025, 271 fewer than in 2020 (−1.2%). That works out to 38 people per square mile of land. Oskaloosa alone is home to 11,493 of them, 52.5% of the total. Reported testing is thin here: 288 tests over 2008 to 2017, or 13.2 for every 1,000 residents (2025 estimate), where Iowa as a whole comes to 29.4.
From Oskaloosa to Keomah Village, CDC publishes no figure by town: each reads Mahaska County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Oskaloosa | 11,493 | −0.4% | 52.5% |
| Pellaextends beyond Mahaska County | 10,992 | +4.9% | Counted whole |
| New Sharon | 1,247 | −0.7% | 5.7% |
| Eddyvilleextends beyond Mahaska County | 960 | −0.7% | Counted whole |
| Fremont | 681 | −2.0% | 3.1% |
| University Park | 472 | −2.9% | 2.2% |
| Beacon | 428 | −0.5% | 2.0% |
| Rose Hill | 157 | −1.9% | 0.7% |
| Leighton | 152 | −1.9% | 0.7% |
| Barnes Cityextends beyond Mahaska County | 146 | −3.9% | Counted whole |
| Keomah Village | 108 | −1.8% | 0.5% |
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 Mahaska County is counted whole, so it has no share.
Mahaska County, Homes
Homes in Mahaska County
Mahaska County is a place of houses on their own lots: 78% of its 9,708 homes are detached single-family houses, against 72% across Iowa. The homes are older than Iowa's as a whole: half were built before 1963 (1971 for Iowa), and 48% date from before 1960. 68% 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 | Mahaska County | Iowa |
|---|---|---|
| Housing units | 9,708 | 1,427,175 |
| Detached houses | 78% | 72% |
| In buildings of 5 or more | 7% | 14% |
| Mobile homes | 5% | 3% |
| Built before 1960 | 48% | 39% |
| Built since 2000 | 14% | 21% |
| Middle year built | 1963 | 1971 |
| Owner-occupied | 68% | 72% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.