Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
Locations and reports
Radon Levels in Poweshiek County, Iowa
EPA puts Poweshiek County in Zone 1, its highest radon zone, and high results are common there: 70.6% of the 419 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
70.6%
12.1 pts above IA
- Poweshiek
- 70.6%
- Iowa
- 58.5%
419 tests, 2008 to 2017
Median result
7.2pCi/L
Action level reached
- Poweshiek
- 7.2 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
419
57th of 99 by tests
- Poweshiek
- 419
- 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
27 of 99
Middle half
- Poweshiek
- 70.6%
- Sioux
- 84.2%
By share, of 99 with 30+ tests
Read a result for Poweshiek County
Starts at Poweshiek County's median, 7.2 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 7.2 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. Poweshiek County's median reported result, 2008 to 2017.
The data
Poweshiek County, At a glance
Poweshiek County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Poweshiek 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 Poweshiek County, 2008 to 2017, laboratory
Under 2 pCi/L: 15%2 to 4 pCi/L: 14%4 pCi/L and above: 71%
Of 419 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 63 | 15.0% |
| 2 to 4 pCi/L | 60 | 14.3% |
| 4 pCi/L and above | 296 | 70.6% |
What these figures count
These are the 419 tests reported to CDC for Poweshiek 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).
Poweshiek County, Compared
Poweshiek County radon figures, compared
Calculated by Radon411More than half: 70.6% of the 419 radon tests reported to CDC for Poweshiek County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 27th of 99 Iowa counties with 30 or more tests for the same period. That is 12.1 points above the 58.5% pooled from 99 Iowa counties.
The median result, 7.2 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 75.5 pCi/L. The rest split 15.0% under 2 pCi/L and 14.3% from 2 to 4 (Iowa: 21.8% and 19.7%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 70.6% share point the same way here.
1 of its 7 bordering counties with figures ran higher, led by Jasper County at 73.3%; Iowa County reported 59.2%. 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 Poweshiek County went from 239 tests (2005 to 2014) to 419 (2008 to 2017), the share going from 69.0% to 70.6%.
Nationally, every county with a figure for the same period pools to 35.7%; Poweshiek County sits 34.9 points above it. CDC also counts 54 tests taken after mitigation in Poweshiek 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.
Poweshiek County, Geology
The ground under Poweshiek County
PredictedUSGS's geologic map puts all of Poweshiek 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.
Poweshiek County beside the ground around it
On high-potential ground Poweshiek 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%.
The map rates the ground, not the air in any home.
Local help
Poweshiek County, Local resources
Radon testing and mitigation in Poweshiek County
Listed radon businesses with an address in Poweshiek 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: Malcom
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
Poweshiek County, Questions
Questions about radon in Poweshiek County
Are radon levels high in Poweshiek County?
Over the 2008 to 2017 laboratory totals, 70.6% of the radon tests reported to CDC for Poweshiek County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 7.2 pCi/L. Of 99 Iowa counties with 30 or more tests for the same period, 26 reported a higher share; pooled, the state comes to 58.5%.
Which counties border Poweshiek County?
Poweshiek County borders 7 counties: Tama County, Iowa County, Mahaska County, Jasper County, Keokuk County, Marshall County and Benton County.
Products
Poweshiek County, Products
Testing a home in Poweshiek County
In Poweshiek County, 70.6% of 419 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 Poweshiek 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
lüft plug-in radon and indoor air quality monitor
- C-NRPP 2024/25: Approved
- Plug-in
- Wi-Fi, Bluetooth
- App only
First reading: Within 90 minutes
Short-term kitempowerDX
Standard Radon Test short-term mail-in radon test kit
- Lab fee included
Method: Passive sampler
In home: 48 to 96 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Poweshiek County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Poweshiek County
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Poweshiek County, Bordering counties
Counties bordering Poweshiek 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 · 2.7 points above Poweshiek County
- Radon levels in Marshall CountyEPA zone 1
70.2%at or above 4 pCi/L
Median 8.2 pCi/L · 570 tests · 0.4 points below Poweshiek County
- Radon levels in Tama CountyEPA zone 1
67.9%at or above 4 pCi/L
Median 7.0 pCi/L · 333 tests · 2.7 points below Poweshiek County
- Radon levels in Benton CountyEPA zone 1
62.1%at or above 4 pCi/L
Median 5.6 pCi/L · 696 tests · 8.5 points below Poweshiek County
- Radon levels in Mahaska CountyEPA zone 1
61.1%at or above 4 pCi/L
Median 5.2 pCi/L · 288 tests · 9.5 points below Poweshiek County
- Radon levels in Keokuk CountyEPA zone 1
60.3%at or above 4 pCi/L
Median 5.2 pCi/L · 214 tests · 10.3 points below Poweshiek County
- Radon levels in Iowa CountyEPA zone 1
59.2%at or above 4 pCi/L
Median 5.1 pCi/L · 519 tests · 11.4 points below Poweshiek County
Poweshiek County, Cities and towns
Cities and towns in Poweshiek County
About 18,368 people live in Poweshiek County by the Census Bureau's estimate for July 1, 2025, 270 fewer than in 2020 (−1.4%). That works out to 31 people per square mile of land. Grinnell alone is home to 9,430 of them, 51.3% of the total. CDC's 419 reported tests for 2008 to 2017 work out to 22.8 per 1,000 residents (2025 estimate), close to Iowa's 29.4.
From Grinnell to Guernsey, CDC publishes no figure by town: each reads Poweshiek County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Grinnell | 9,430 | −1.1% | 51.3% |
| Brooklyn | 1,467 | −2.3% | 8.0% |
| Montezuma | 1,417 | −2.0% | 7.7% |
| Victorextends beyond Poweshiek County | 855 | −2.2% | Counted whole |
| Malcom | 259 | −3.7% | 1.4% |
| Deep River | 245 | −1.2% | 1.3% |
| Barnes Cityextends beyond Poweshiek County | 146 | −3.9% | Counted whole |
| Searsboro | 128 | −1.5% | 0.7% |
| Hartwick | 91 | −1.1% | 0.5% |
| Guernsey | 61 | −1.6% | 0.3% |
10 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 Poweshiek County is counted whole, so it has no share.
Poweshiek County, Homes
Homes in Poweshiek County
Poweshiek County is a place of houses on their own lots: 77% of its 8,946 homes are detached single-family houses, against 72% across Iowa. Half of its homes were built before 1970, close to Iowa's 1971: 40% date from before 1960 and 16% from 2000 or later. 71% 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 | Poweshiek County | Iowa |
|---|---|---|
| Housing units | 8,946 | 1,427,175 |
| Detached houses | 77% | 72% |
| In buildings of 5 or more | 8% | 14% |
| Mobile homes | 5% | 3% |
| Built before 1960 | 40% | 39% |
| Built since 2000 | 16% | 21% |
| Middle year built | 1970 | 1971 |
| Owner-occupied | 71% | 72% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.