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 Iowa County, Wisconsin
EPA puts Iowa County in Zone 1, its highest radon zone, and high results are common there: 61.0% of the 146 radon tests reported to CDC (2023) 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
61.0%
25.3 pts above WI
- Iowa
- 61.0%
- Wisconsin
- 35.7%
146 tests, 2023
Median result
4.8pCi/L
Action level reached
- Iowa
- 4.8 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2023
Tests reported
146
36th of 69 by tests
- Iowa
- 146
- Dane
- 2,887
Reported to CDC before any fix, 2023
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Wisconsin
2 of 69
Top quarter
- Iowa
- 61.0%
- Langlade
- 65.8%
By share, of 69 with 30+ tests
Read a result for Iowa County
Starts at Iowa County's median, 4.8 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.8 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. Iowa County's median reported result, 2023.
The data
Iowa County, At a glance
Iowa County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Iowa County in
USGS geologic potential: High across 95% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Iowa County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 52.9% |
| 2015 | 63.4% |
| 2016 | 74.2% |
| 2017 | 62.2% |
| 2019 | 29.3% |
| 2020 | 55.2% |
| 2021 | 50.9% |
| 2022 | 69.6% |
| 2023 | 61.0% |
2023: 61.0%. Across these years the share ran from 29.3% to 74.2%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 146 tests reported to CDC for Iowa County over 2023, 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: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).
Iowa County, Compared
Iowa County radon figures, compared
Calculated by Radon411More than half: 61.0% of the 146 radon tests reported to CDC for Iowa County in 2023 read at least 4 pCi/L. That places it 2nd of 69 Wisconsin counties with 30 or more tests for the same period. That is 25.3 points above the 35.7% pooled from 72 Wisconsin counties.
The median result, 4.8 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 53.6 pCi/L. The rest split 18.5% under 2 pCi/L and 20.5% from 2 to 4 (Wisconsin: 41.4% and 23.0%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 61.0% share point the same way here.
No bordering county with a figure for the same period reported a higher share; the closest is Lafayette County at 52.2%, the lowest Richland County at 33.3%. Statewide for the same period, Langlade County reported the highest share (65.8%) and Bayfield County the lowest (5.7%).
The busiest year on file was 2019, with 198 tests reported; the quietest, 2021, had 53.
Over 9 years of annual figures the share rose 8.1 points, from 52.9% in 2014 to 61.0% in 2023; its peak was 74.2% in 2016. Nationally, every county with a figure for the same period pools to 33.4%; Iowa County sits 27.6 points above it. CDC also counts 9 tests taken after mitigation in Iowa County for the same period: tests in homes where a fix was already in.
Iowa CountyWisconsin, pooled
61.0% % of tests35.7% % of tests
| Year | Tests | Iowa County, at or above 4 pCi/L | Wisconsin, pooled |
|---|---|---|---|
| 2014 | 121 | 52.9% | 51.1% |
| 2015 | 93 | 63.4% | 51.6% |
| 2016 | 89 | 74.2% | 45.2% |
| 2017 | 98 | 62.2% | 44.8% |
| 2019 | 198 | 29.3% | 42.9% |
| 2020 | 143 | 55.2% | 27.0% |
| 2021 | 53 | 50.9% | 39.9% |
| 2022 | 56 | 69.6% | 42.9% |
| 2023 | 146 | 61.0% | 35.7% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Iowa County, Geology
The ground under Iowa County
PredictedMost of the ground under Iowa County is one class on USGS's geologic map: 94.7% of its land is high radon potential, with 5.3% moderate. The map puts 94.7% of Iowa County in the area it calls Driftless Area and 5.3% in Driftless Area. USGS gives the first a radon index of 12, in the high band (12 to 17), and the second 10, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Driftless Area | Cambrian sandstone and Ordovician limestone and dolostone. | High | 12 | 94.7% |
| Driftless Area | Cambrian sandstone. | Moderate | 10 | 5.3% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Iowa County beside the ground around it
Iowa County has more high-potential ground than Wisconsin as a whole: 94.7% of its land against 34.8%. Of the 6 counties that border it, 3 have more high-potential ground, Grant County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Iowa County, Local resources
Radon testing and mitigation in Iowa County
- Wisconsin's radon programWisconsin Department of Health ServicesWisconsin's radon program does not license radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in Wisconsin.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
We recommend starting with your regional Radon Information Center since many centers provide test kits for free or reduced cost, and often with laboratory fees covered.
- Compare kits
- Professionals in Wisconsin19 professionals are listed in Wisconsin.
What Wisconsin's program says
- Phone
- 1-888-569-7236
- DHSRadon@dhs.wisconsin.gov
- Licensing of radon professionals
The State of Wisconsin does not require contractors performing radon measurement or mitigation work to be state licensed or nationally certified.
What it means
Iowa County, Questions
Questions about radon in Iowa County
Are radon levels high in Iowa County?
In 2023, 61.0% of the radon tests reported to CDC for Iowa County, Wisconsin were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.8 pCi/L. Of 69 Wisconsin counties with 30 or more tests for the same period, 1 reported a higher share; pooled, the state comes to 35.7%.
Which counties border Iowa County?
Iowa County borders 6 counties: Lafayette County, Richland County, Grant County, Sauk County, Dane County and Green County.
Products
Iowa County, Products
Testing a home in Iowa County
In Iowa County, 61.0% of 146 tests reported to CDC in 2023 reached 4 pCi/L, against 35.7% pooled across Wisconsin. In Zone 1 the year-round level in Iowa 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
MonitorAEGTEST
HOUND-3699 radon monitor with a 2.1-inch touchscreen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
First reading: Within 1 hour
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
Iowa County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Iowa County
Explore
Iowa County, Bordering counties
Counties bordering Iowa County
Calculated by Radon411- Radon levels in Lafayette CountyEPA zone 1
52.2%at or above 4 pCi/L
Median 4.2 pCi/L · 46 tests · 8.8 points below Iowa County
- Radon levels in Grant CountyEPA zone 1
48.3%at or above 4 pCi/L
Median 3.5 pCi/L · 323 tests · 12.7 points below Iowa County
- Radon levels in Sauk CountyEPA zone 2
41.1%at or above 4 pCi/L
Median 3.3 pCi/L · 241 tests · 19.9 points below Iowa County
- Radon levels in Dane CountyEPA zone 1
34.9%at or above 4 pCi/L
Median 2.5 pCi/L · 2,887 tests · 26.1 points below Iowa County
- Radon levels in Green CountyEPA zone 1
33.6%at or above 4 pCi/L
Median 2.1 pCi/L · 235 tests · 27.4 points below Iowa County
- Radon levels in Richland CountyEPA zone 1
33.3%at or above 4 pCi/L
Median 2.9 pCi/L · 48 tests · 27.7 points below Iowa County
Iowa County, Cities and towns
Cities and towns in Iowa County
The Census Bureau estimates 23,951 residents in Iowa County for July 1, 2025, 235 more than in 2020 (+1.0%). That works out to 31 people per square mile of land. Its largest town, Dodgeville, has 5,076 residents, 21.2% of the total. Testing is reported here more often than across the state: CDC's 146 reported tests for 2023 come to 6.1 for every 1,000 residents (2025 estimate), against 3.5 for Wisconsin.
From Dodgeville to Rewey, CDC publishes no figure by town: each reads Iowa County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Dodgeville | 5,076 | +1.8% | 21.2% |
| Mineral Point | 2,555 | −0.9% | 10.7% |
| Barneveld | 1,333 | +1.0% | 5.6% |
| Muscodaextends beyond Iowa County | 1,304 | +0.2% | Counted whole |
| Arena | 916 | +7.9% | 3.8% |
| Highland | 860 | −1.5% | 3.6% |
| Blanchardvilleextends beyond Iowa County | 829 | +1.6% | Counted whole |
| Montfortextends beyond Iowa County | 734 | +3.1% | Counted whole |
| Ridgeway | 650 | +3.0% | 2.7% |
| Livingstonextends beyond Iowa County | 636 | −0.6% | Counted whole |
| Avoca | 547 | −1.4% | 2.3% |
| Linden | 498 | −1.6% | 2.1% |
- Cobb
- Hollandale
- Rewey
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 Iowa County is counted whole, so it has no share.
Iowa County, Homes
Homes in Iowa County
Iowa County is a place of houses on their own lots: 81% of its 11,007 homes are detached single-family houses, against 66% across Wisconsin. Half of its homes were built before 1975, close to Wisconsin's 1975: 39% date from before 1960 and 20% from 2000 or later. Owners live in 77% of the occupied homes (Wisconsin: 68%), so for most households a test and a fix are their own to order.
| Homes | Iowa County | Wisconsin |
|---|---|---|
| Housing units | 11,007 | 2,750,750 |
| Detached houses | 81% | 66% |
| In buildings of 5 or more | 5% | 17% |
| Mobile homes | 3% | 3% |
| Built before 1960 | 39% | 34% |
| Built since 2000 | 20% | 20% |
| Middle year built | 1975 | 1975 |
| Owner-occupied | 77% | 68% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.