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 Decatur County, Iowa
EPA puts Decatur County in Zone 1, its highest radon zone, and 25.9% of its 85 reported radon tests (2008 to 2017, laboratory totals) were 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
25.9%
32.6 pts below IA
- Decatur
- 25.9%
- Iowa
- 58.5%
85 tests, 2008 to 2017
Median result
2.5pCi/L
Below action level
- Decatur
- 2.5 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
85
94th of 99 by tests
- Decatur
- 85
- 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
99 of 99
Lowest quarter
- Decatur
- 25.9%
- Sioux
- 84.2%
By share, of 99 with 30+ tests
Read a result for Decatur County
Starts at Decatur County's median, 2.5 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.5 pCi/L
Between 2 and 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Decatur County's median reported result, 2008 to 2017.
The data
Decatur County, At a glance
Decatur County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Decatur County in
USGS geologic potential: High across 91% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Decatur County, 2008 to 2017, laboratory
Under 2 pCi/L: 39%2 to 4 pCi/L: 35%4 pCi/L and above: 26%
Of 85 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 33 | 38.8% |
| 2 to 4 pCi/L | 30 | 35.3% |
| 4 pCi/L and above | 22 | 25.9% |
What these figures count
These are the 85 tests reported to CDC for Decatur 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).
Decatur County, Compared
Decatur County radon figures, compared
Calculated by Radon411Decatur County's 85 reported tests over the 2008 to 2017 laboratory totals had a middle value of 2.5 pCi/L and a maximum of 19.2 pCi/L, and 25.9% reached 4 pCi/L. Iowa as a whole (99 Iowa counties, pooled) comes to 58.5%: 32.6 points higher than here.
Among its state's counties it ranks 99th of 99 Iowa counties with 30 or more tests for the same period. Statewide for the same period, Sioux County reported the highest share (84.2%) and Ringgold County the lowest (28.7%).
Below the action level, 33 tests (38.8%) came in under 2 pCi/L, against 21.8% statewide, and 30 tests (35.3%) fell between 2 and 4, against 19.7% statewide. CDC's ten-year totals for Decatur County went from 82 tests (2005 to 2014) to 85 (2008 to 2017), the share going from 37.8% to 25.9%.
EPA's 1993 zone map puts Decatur County in Zone 1, a predicted county average above 4 pCi/L. USGS geology rates 91% of the county's land high radon potential.
Next door, the shares run from 28.7% in Ringgold County to 61.8% in Union County.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Decatur County, Geology
The ground under Decatur County
PredictedMost of the ground under Decatur County is one class on USGS's geologic map: 91.4% of its land is high radon potential, with 8.6% moderate. The map puts 91.4% of Decatur County in the area it calls Loess-Covered Drift Plains and 8.6% in Dissected Till Plains. USGS gives the first a radon index of 13, in the high band (12 to 17), and the second 11, in the moderate band (9 to 11).
| 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 | 91.4% |
| Dissected Till Plains | Till-covered Pennsylvanian sandstone, shale, and limestone. | Moderate | 11 | 8.6% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Decatur County beside the ground around it
On high-potential ground Decatur County is close to Iowa as a whole: 91.4% of its land against 98.8%. Of the 7 counties that border it, 4 have more high-potential ground, Clarke County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Decatur County, Local resources
Radon testing and mitigation in Decatur County
Listed radon businesses with an address in Decatur 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: Lamoni
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
Decatur County, Questions
Questions about radon in Decatur County
Are radon levels high in Decatur County?
Over the 2008 to 2017 laboratory totals, 25.9% of the radon tests reported to CDC for Decatur County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.5 pCi/L. Of 99 Iowa counties with 30 or more tests for the same period, 98 reported a higher share; pooled, the state comes to 58.5%.
Which counties border Decatur County?
Decatur County borders 7 counties: Clarke County, IA, Ringgold County, IA, Wayne County, IA, Mercer County, MO, Harrison County, MO, Union County, IA and Lucas County, IA.
Products
Decatur County, Products
Testing a home in Decatur County
In Decatur County, 25.9% of 85 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 Decatur 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
EcoQube Wi-Fi continuous radon monitor
- C-NRPP 2024/25: Approved
- Plug-in
- Wi-Fi
- App only
Method: Ion chamber
First reading: Within 10 minutes
Short-term kit
Air Chek Short-Term radon test kit you hang, lab fee included
- Lab fee included
In home: 72 to 168 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Decatur County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Decatur County
Explore
Decatur County, Bordering counties
Counties bordering Decatur County
Calculated by Radon411- Radon levels in Union County, IAEPA zone 1
61.8%at or above 4 pCi/L
Median 4.9 pCi/L · 131 tests · 35.9 points above Decatur County
- Radon levels in Clarke County, IAEPA zone 1
45.8%at or above 4 pCi/L
Median 3.5 pCi/L · 120 tests · 19.9 points above Decatur County
- Radon levels in Lucas County, IAEPA zone 1
39.3%at or above 4 pCi/L
Median 3.3 pCi/L · 84 tests · 13.4 points above Decatur County
- Radon levels in Wayne County, IAEPA zone 1
34.8%at or above 4 pCi/L
Median 3.0 pCi/L · 46 tests · 8.9 points above Decatur County
- Radon levels in Harrison County, MOEPA zone 2
29.2%at or above 4 pCi/L
Median 1.9 pCi/L · 24 tests · 3.3 points above Decatur County
- Radon levels in Ringgold County, IAEPA zone 1
28.7%at or above 4 pCi/L
Median 2.6 pCi/L · 87 tests · 2.8 points above Decatur County
- Radon levels in Mercer County, MOEPA zone 2
27.3%at or above 4 pCi/L
Median 1.7 pCi/L · 11 tests · 1.4 points above Decatur County
Decatur County, Cities and towns
Cities and towns in Decatur County
About 7,655 people live in Decatur County by the Census Bureau's estimate for July 1, 2025, 73 fewer than in 2020 (−0.9%). That works out to 14 people per square mile of land. Its largest town, Lamoni, has 2,074 residents, 27.1% of the total. Reported testing is thin here: 85 tests over 2008 to 2017, or 11.1 for every 1,000 residents (2025 estimate), where Iowa as a whole comes to 29.4.
From Lamoni to Decatur City, CDC publishes no figure by town: each reads Decatur County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Lamoni | 2,074 | −0.2% | 27.1% |
| Leon | 1,773 | −1.8% | 23.2% |
| Grand River | 189 | −2.1% | 2.5% |
| Davis City | 178 | −1.1% | 2.3% |
| Van Wert | 175 | −1.1% | 2.3% |
| Garden Grove | 174 | −1.1% | 2.3% |
| Weldon | 136 | −2.9% | 1.8% |
| Pleasanton | 33 | Level | 0.4% |
| Le Roy | 10 | Level | 0.1% |
- Decatur City
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).
Decatur County, Homes
Homes in Decatur County
Decatur County is a place of houses on their own lots: 78% of its 3,651 homes are detached single-family houses, against 72% across Iowa. Half of its homes were built before 1968, close to Iowa's 1971: 42% date from before 1960 and 17% from 2000 or later. 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 | Decatur County | Iowa |
|---|---|---|
| Housing units | 3,651 | 1,427,175 |
| Detached houses | 78% | 72% |
| In buildings of 5 or more | 7% | 14% |
| Mobile homes | 7% | 3% |
| Built before 1960 | 42% | 39% |
| Built since 2000 | 17% | 21% |
| Middle year built | 1968 | 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.