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 Woodbury County, Iowa
EPA puts Woodbury County in Zone 1, its highest radon zone, and high results are common there: 69.2% of the 3,541 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
69.2%
10.7 pts above IA
- Woodbury
- 69.2%
- Iowa
- 58.5%
3,541 tests, 2008 to 2017
Median result
6.1pCi/L
Action level reached
- Woodbury
- 6.1 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
3,541
5th of 99 by tests
- Woodbury
- 3,541
- 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
36 of 99
Middle half
- Woodbury
- 69.2%
- Sioux
- 84.2%
By share, of 99 with 30+ tests
Read a result for Woodbury County
Starts at Woodbury County's median, 6.1 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 6.1 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. Woodbury County's median reported result, 2008 to 2017.
The data
Woodbury County, At a glance
Woodbury County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Woodbury 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 Woodbury County, 2008 to 2017, laboratory
Under 2 pCi/L: 10%2 to 4 pCi/L: 21%4 pCi/L and above: 69%
Of 3,541 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 356 | 10.1% |
| 2 to 4 pCi/L | 733 | 20.7% |
| 4 pCi/L and above | 2,452 | 69.2% |
What these figures count
These are the 3,541 tests reported to CDC for Woodbury 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).
Woodbury County, Compared
Woodbury County radon figures, compared
Calculated by Radon411More than half: 69.2% of the 3,541 radon tests reported to CDC for Woodbury County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 36th of 99 Iowa counties with 30 or more tests for the same period. That is 10.7 points above the 58.5% pooled from 99 Iowa counties.
The median result, 6.1 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 83.0 pCi/L. The rest split 10.1% under 2 pCi/L and 20.7% from 2 to 4 (Iowa: 21.8% and 19.7%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 69.2% share point the same way here.
6 of its 8 bordering counties with figures ran higher, led by Plymouth County at 82.3%; Union County, SD reported 51.1%. 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 Woodbury County went from 1,731 tests (2005 to 2014) to 3,541 (2008 to 2017), the share going from 69.1% to 69.2%.
Nationally, every county with a figure for the same period pools to 35.7%; Woodbury County sits 33.5 points above it. CDC also counts 268 tests taken after mitigation in Woodbury 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.
Woodbury County, Geology
The ground under Woodbury County
PredictedUSGS's geologic map puts all of Woodbury 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 | 99.9% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Woodbury County beside the ground around it
On high-potential ground Woodbury 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; Cherokee County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Woodbury County, Local resources
Radon testing and mitigation in Woodbury County
Listed radon businesses with an address in Woodbury 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: Sioux City
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
Woodbury County, Questions
Questions about radon in Woodbury County
Are radon levels high in Woodbury County?
Over the 2008 to 2017 laboratory totals, 69.2% of the radon tests reported to CDC for Woodbury County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 6.1 pCi/L. Of 99 Iowa counties with 30 or more tests for the same period, 35 reported a higher share; pooled, the state comes to 58.5%.
Which counties border Woodbury County?
Woodbury County borders 8 counties: Monona County, IA, Dakota County, NE, Plymouth County, IA, Ida County, IA, Thurston County, NE, Cherokee County, IA, Crawford County, IA and Union County, SD.
Products
Woodbury County, Products
Testing a home in Woodbury County
In Woodbury County, 69.2% of 3,541 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 Woodbury 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
RadonScan USB-powered radon monitor with a color screen
- C-NRPP 2024/25: Not included
- Plug-in
- Alarm
- Screen
First reading: Within 5 minutes
Short-term kitKidde
442020 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 3 days
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Woodbury County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Woodbury County
Explore
Woodbury County, Bordering counties
Counties bordering Woodbury County
Calculated by Radon411- Radon levels in Plymouth County, IAEPA zone 1
82.3%at or above 4 pCi/L
Median 8.6 pCi/L · 1,405 tests · 13.1 points above Woodbury County
- Radon levels in Thurston County, NEEPA zone 1
77.2%at or above 4 pCi/L
Median 7.0 pCi/L · 114 tests · 8.0 points above Woodbury County
- Radon levels in Crawford County, IAEPA zone 1
74.8%at or above 4 pCi/L
Median 7.0 pCi/L · 373 tests · 5.6 points above Woodbury County
- Radon levels in Monona County, IAEPA zone 1
74.6%at or above 4 pCi/L
Median 7.0 pCi/L · 603 tests · 5.4 points above Woodbury County
- Radon levels in Cherokee County, IAEPA zone 1
74.5%at or above 4 pCi/L
Median 7.6 pCi/L · 795 tests · 5.3 points above Woodbury County
- Radon levels in Ida County, IAEPA zone 1
71.7%at or above 4 pCi/L
Median 7.4 pCi/L · 399 tests · 2.5 points above Woodbury County
- Radon levels in Dakota County, NEEPA zone 1
61.5%at or above 4 pCi/L
Median 5.0 pCi/L · 322 tests · 7.7 points below Woodbury County
- Radon levels in Union County, SDEPA zone 1
51.1%at or above 4 pCi/L
Median 4.1 pCi/L · 348 tests · 18.1 points below Woodbury County
Woodbury County, Cities and towns
Cities and towns in Woodbury County
The Census Bureau estimates 106,649 residents in Woodbury County for July 1, 2025, 700 more than in 2020 (+0.7%). That works out to 122 people per square mile of land. Sioux City, the largest place on its list (86,356 residents in all), extends beyond Woodbury County, so no share of the total is worked out for it. CDC's 3,541 reported tests for 2008 to 2017 work out to 33.2 per 1,000 residents (2025 estimate), close to Iowa's 29.4.
From Sioux City to Oto, CDC publishes no figure by town: each reads Woodbury County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Sioux Cityextends beyond Woodbury County | 86,356 | +0.5% | Counted whole |
| Sergeant Bluff | 5,324 | +6.3% | 5.0% |
| Moville | 1,708 | +1.0% | 1.6% |
| Sloan | 1,078 | +2.9% | 1.0% |
| Lawton | 947 | +0.2% | 0.9% |
| Correctionville | 756 | −0.9% | 0.7% |
| Anthon | 533 | −1.5% | 0.5% |
| Pierson | 327 | −2.4% | 0.3% |
| Danbury | 308 | −2.8% | 0.3% |
| Salix | 305 | +1.7% | 0.3% |
| Bronson | 295 | −0.7% | 0.3% |
| Hornick | 253 | −1.9% | 0.2% |
Places in Woodbury County with a city page: 1 of 1
- Cushing
- Smithland
- Oto
15 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Woodbury County is counted whole, so it has no share.
Woodbury County, Homes
Homes in Woodbury County
Of Woodbury County's 43,121 homes, 73% are detached houses, against 72% across Iowa; 14% are in buildings of five or more homes. The homes are older than Iowa's as a whole: half were built before 1958 (1971 for Iowa), and 53% 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 | Woodbury County | Iowa |
|---|---|---|
| Housing units | 43,121 | 1,427,175 |
| Detached houses | 73% | 72% |
| In buildings of 5 or more | 14% | 14% |
| Mobile homes | 4% | 3% |
| Built before 1960 | 53% | 39% |
| Built since 2000 | 11% | 21% |
| Middle year built | 1958 | 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.