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 Louisa County, Iowa
EPA puts Louisa County in Zone 1, its highest radon zone, and high results are common there: 52.1% of the 96 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
52.1%
6.4 pts below IA
- Louisa
- 52.1%
- Iowa
- 58.5%
96 tests, 2008 to 2017
Median result
4.1pCi/L
Action level reached
- Louisa
- 4.1 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
96
91st of 99 by tests
- Louisa
- 96
- 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
77 of 99
Lowest quarter
- Louisa
- 52.1%
- Sioux
- 84.2%
By share, of 99 with 30+ tests
Read a result for Louisa County
Starts at Louisa County's median, 4.1 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.1 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. Louisa County's median reported result, 2008 to 2017.
The data
Louisa County, At a glance
Louisa County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Louisa 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 Louisa County, 2008 to 2017, laboratory
Under 2 pCi/L: 24%2 to 4 pCi/L: 24%4 pCi/L and above: 52%
Of 96 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 23 | 24.0% |
| 2 to 4 pCi/L | 23 | 24.0% |
| 4 pCi/L and above | 50 | 52.1% |
What these figures count
These are the 96 tests reported to CDC for Louisa 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).
Louisa County, Compared
Louisa County radon figures, compared
Calculated by Radon411More than half: 52.1% of the 96 radon tests reported to CDC for Louisa County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 77th of 99 Iowa counties with 30 or more tests for the same period. That is 6.4 points below the 58.5% pooled from 99 Iowa counties.
The median result, 4.1 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 39.8 pCi/L. The rest split 24.0% under 2 pCi/L and 24.0% from 2 to 4 (Iowa: 21.8% and 19.7%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 52.1% share point the same way here.
2 of its 7 bordering counties with figures ran higher, led by Mercer County, IL at 67.1%; Johnson County reported 41.6%. 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 Louisa County went from 79 tests (2005 to 2014) to 96 (2008 to 2017), the share going from 55.7% to 52.1%.
Nationally, every county with a figure for the same period pools to 35.7%; Louisa County sits 16.4 points above it. CDC also counts 11 tests taken after mitigation in Louisa 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.
Louisa County, Geology
The ground under Louisa County
PredictedUSGS's geologic map puts all of Louisa County's mapped land in one class: high radon potential. 99.4% 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 | 99.4% |
| Galesburg Plain | Illinoian glacial deposits and loess over Paleozoic sedimentary rocks. | High | 13 | 0.6% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Louisa County beside the ground around it
On high-potential ground Louisa 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; Des Moines County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Louisa County, Local resources
Radon testing and mitigation in Louisa 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.
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
Louisa County, Questions
Questions about radon in Louisa County
Are radon levels high in Louisa County?
Over the 2008 to 2017 laboratory totals, 52.1% of the radon tests reported to CDC for Louisa County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.1 pCi/L. Of 99 Iowa counties with 30 or more tests for the same period, 76 reported a higher share; pooled, the state comes to 58.5%.
Which counties border Louisa County?
Louisa County borders 7 counties: Muscatine County, IA, Washington County, IA, Henry County, IA, Mercer County, IL, Des Moines County, IA, Johnson County, IA and Rock Island County, IL.
Products
Louisa County, Products
Testing a home in Louisa County
In Louisa County, 52.1% of 96 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 Louisa 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
MonitorINKBIRD
INK-RD3 battery radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- Battery
- Screen
First reading: Within 24 hours
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
Louisa County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Louisa County
Explore
Louisa County, Bordering counties
Counties bordering Louisa County
Calculated by Radon411- Radon levels in Mercer County, ILEPA zone 1
67.1%at or above 4 pCi/L
Median 6.8 pCi/L · 343 tests · 15.0 points above Louisa County
- Radon levels in Washington County, IAEPA zone 1
54.9%at or above 4 pCi/L
Median 4.6 pCi/L · 1,186 tests · 2.8 points above Louisa County
- Radon levels in Des Moines County, IAEPA zone 1
51.1%at or above 4 pCi/L
Median 4.2 pCi/L · 436 tests · 1.0 points below Louisa County
- Radon levels in Rock Island County, ILEPA zone 1
48.3%at or above 4 pCi/L
Median 3.8 pCi/L · 3,736 tests · 3.8 points below Louisa County
- Radon levels in Muscatine County, IAEPA zone 1
46.5%at or above 4 pCi/L
Median 3.7 pCi/L · 954 tests · 5.6 points below Louisa County
- Radon levels in Henry County, IAEPA zone 1
46.4%at or above 4 pCi/L
Median 3.4 pCi/L · 168 tests · 5.7 points below Louisa County
- Radon levels in Johnson County, IAEPA zone 1
41.6%at or above 4 pCi/L
Median 3.2 pCi/L · 7,321 tests · 10.5 points below Louisa County
Louisa County, Cities and towns
Cities and towns in Louisa County
About 10,416 people live in Louisa County by the Census Bureau's estimate for July 1, 2025, 406 fewer than in 2020 (−3.8%). That works out to 26 people per square mile of land. No town dominates: Wapello, the largest, has 1,979 residents, 19.0% of the total. Together its 9 incorporated places hold 57.8% of those residents; the other 42.2% live outside any of them. Reported testing is thin here: 96 tests over 2008 to 2017, or 9.2 for every 1,000 residents (2025 estimate), where Iowa as a whole comes to 29.4.
From Wapello to Cotter, CDC publishes no figure by town: each reads Louisa County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Wapello | 1,979 | −4.9% | 19.0% |
| Columbus Junction | 1,772 | −4.2% | 17.0% |
| Morning Sun | 688 | −8.3% | 6.6% |
| Grandview | 415 | −4.6% | 4.0% |
| Columbus City | 374 | −3.1% | 3.6% |
| Letts | 350 | −3.3% | 3.4% |
| Fredonia | 211 | −3.7% | 2.0% |
| Oakville | 193 | −2.5% | 1.9% |
| Cotter | 39 | Level | 0.4% |
9 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).
Louisa County, Homes
Homes in Louisa County
Louisa County is a place of houses on their own lots: 86% of its 4,736 homes are detached single-family houses, against 72% across Iowa. The homes are older than Iowa's as a whole: half were built before 1962 (1971 for Iowa), and 48% date from before 1960. Owners live in 80% of the occupied homes (Iowa: 72%), so for most households a test and a fix are their own to order.
| Homes | Louisa County | Iowa |
|---|---|---|
| Housing units | 4,736 | 1,427,175 |
| Detached houses | 86% | 72% |
| In buildings of 5 or more | 2% | 14% |
| Mobile homes | 8% | 3% |
| Built before 1960 | 48% | 39% |
| Built since 2000 | 14% | 21% |
| Middle year built | 1962 | 1971 |
| Owner-occupied | 80% | 72% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.