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 Shelby County, Iowa
EPA puts Shelby County in Zone 1, its highest radon zone, and high results are common there: 78.4% of the 857 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
78.4%
19.9 pts above IA
- Shelby
- 78.4%
- Iowa
- 58.5%
857 tests, 2008 to 2017
Median result
9.0pCi/L
Action level reached
- Shelby
- 9.0 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
857
24th of 99 by tests
- Shelby
- 857
- 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
5 of 99
Top quarter
- Shelby
- 78.4%
- Sioux
- 84.2%
By share, of 99 with 30+ tests
Read a result for Shelby County
Starts at Shelby County's median, 9.0 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 9.0 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. Shelby County's median reported result, 2008 to 2017.
The data
Shelby County, At a glance
Shelby County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Shelby 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 Shelby County, 2008 to 2017, laboratory
Under 2 pCi/L: 10%2 to 4 pCi/L: 12%4 pCi/L and above: 78%
Of 857 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 85 | 9.9% |
| 2 to 4 pCi/L | 100 | 11.7% |
| 4 pCi/L and above | 672 | 78.4% |
What these figures count
These are the 857 tests reported to CDC for Shelby 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).
Shelby County, Compared
Shelby County radon figures, compared
Calculated by Radon411More than half: 78.4% of the 857 radon tests reported to CDC for Shelby County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 5th of 99 Iowa counties with 30 or more tests for the same period. That is 19.9 points above the 58.5% pooled from 99 Iowa counties.
The median result, 9.0 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 133.2 pCi/L. The rest split 9.9% under 2 pCi/L and 11.7% from 2 to 4 (Iowa: 21.8% and 19.7%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 78.4% share point the same way here.
No bordering county with a figure for the same period reported a higher share; the closest is Audubon County at 78.3%, the lowest Pottawattamie County at 57.4%. 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 Shelby County went from 543 tests (2005 to 2014) to 857 (2008 to 2017), the share going from 81.8% to 78.4%.
Nationally, every county with a figure for the same period pools to 35.7%; Shelby County sits 42.7 points above it. CDC also counts 63 tests taken after mitigation in Shelby 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.
Shelby County, Geology
The ground under Shelby County
PredictedUSGS's geologic map puts all of Shelby 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.
Shelby County beside the ground around it
On high-potential ground Shelby 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; Audubon County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Shelby County, Local resources
Radon testing and mitigation in Shelby County
Listed radon businesses with an address in Shelby 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: Elk Horn
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
Shelby County, Questions
Questions about radon in Shelby County
Are radon levels high in Shelby County?
Over the 2008 to 2017 laboratory totals, 78.4% of the radon tests reported to CDC for Shelby County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 9.0 pCi/L. Of 99 Iowa counties with 30 or more tests for the same period, 4 reported a higher share; pooled, the state comes to 58.5%.
Which counties border Shelby County?
Shelby County borders 6 counties: Audubon County, Crawford County, Harrison County, Cass County, Pottawattamie County and Carroll County.
Products
Shelby County, Products
Testing a home in Shelby County
In Shelby County, 78.4% of 857 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 Shelby 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
EcoBlu plug-in digital radon monitor with a display
- C-NRPP 2024/25: Not included
- Plug-in
- Alarm
- Screen
Method: Ion chamber
First reading: Within 10 minutes
Short-term kit
RA400 short-term liquid scintillation radon test kit, lab fee included
- Lab fee included
Method: Liquid scintillation
In home: 48 to 96 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Shelby County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Shelby County
Explore
Shelby County, Bordering counties
Counties bordering Shelby County
Calculated by Radon411- Radon levels in Audubon CountyEPA zone 1
78.3%at or above 4 pCi/L
Median 9.5 pCi/L · 189 tests · 0.1 points below Shelby County
- Radon levels in Carroll CountyEPA zone 1
77.6%at or above 4 pCi/L
Median 7.8 pCi/L · 594 tests · 0.8 points below Shelby County
- Radon levels in Cass CountyEPA zone 1
77.4%at or above 4 pCi/L
Median 8.1 pCi/L · 327 tests · 1.0 points below Shelby County
- Radon levels in Crawford CountyEPA zone 1
74.8%at or above 4 pCi/L
Median 7.0 pCi/L · 373 tests · 3.6 points below Shelby County
- Radon levels in Harrison CountyEPA zone 1
69.8%at or above 4 pCi/L
Median 6.2 pCi/L · 367 tests · 8.6 points below Shelby County
- Radon levels in Pottawattamie CountyEPA zone 1
57.4%at or above 4 pCi/L
Median 4.7 pCi/L · 1,868 tests · 21.0 points below Shelby County
Shelby County, Cities and towns
Cities and towns in Shelby County
Shelby County's population has barely moved since 2020: 11,689 residents on July 1, 2025 against 11,718 then, by the Census Bureau's estimates. That works out to 20 people per square mile of land. Its largest town, Harlan, has 4,859 residents, 41.6% of the total. Testing is reported here more often than across the state: CDC's 857 reported tests for 2008 to 2017 come to 73.3 for every 1,000 residents (2025 estimate), against 29.4 for Iowa.
From Harlan to Kirkman, CDC publishes no figure by town: each reads Shelby County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Harlan | 4,859 | −0.7% | 41.6% |
| Shelbyextends beyond Shelby County | 727 | +0.3% | Counted whole |
| Elk Horn | 619 | +3.2% | 5.3% |
| Earling | 387 | −1.8% | 3.3% |
| Irwin | 315 | −1.3% | 2.7% |
| Defiance | 242 | −1.6% | 2.1% |
| Panama | 231 | −0.9% | 2.0% |
| Portsmouth | 186 | −0.5% | 1.6% |
| Westphalia | 132 | +1.5% | 1.1% |
| Tennant | 81 | +3.8% | 0.7% |
| Kirkman | 56 | +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 Shelby County is counted whole, so it has no share.
Shelby County, Homes
Homes in Shelby County
Shelby County is a place of houses on their own lots: 88% of its 5,429 homes are detached single-family houses, against 72% across Iowa. The homes are older than Iowa's as a whole: half were built before 1946 (1971 for Iowa), and 61% date from before 1960. Owners live in 76% of the occupied homes (Iowa: 72%), so for most households a test and a fix are their own to order.
| Homes | Shelby County | Iowa |
|---|---|---|
| Housing units | 5,429 | 1,427,175 |
| Detached houses | 88% | 72% |
| In buildings of 5 or more | 4% | 14% |
| Mobile homes | 2% | 3% |
| Built before 1960 | 61% | 39% |
| Built since 2000 | 8% | 21% |
| Middle year built | 1946 | 1971 |
| Owner-occupied | 76% | 72% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.