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 Jefferson County, Iowa
EPA puts Jefferson County in Zone 1, its highest radon zone, and 33.5% of its 841 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
33.5%
25.0 pts below IA
- Jefferson
- 33.5%
- Iowa
- 58.5%
841 tests, 2008 to 2017
Median result
2.6pCi/L
Below action level
- Jefferson
- 2.6 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
841
25th of 99 by tests
- Jefferson
- 841
- 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
96 of 99
Lowest quarter
- Jefferson
- 33.5%
- Sioux
- 84.2%
By share, of 99 with 30+ tests
Read a result for Jefferson County
Starts at Jefferson County's median, 2.6 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.6 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. Jefferson County's median reported result, 2008 to 2017.
The data
Jefferson County, At a glance
Jefferson County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Jefferson 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 Jefferson County, 2008 to 2017, laboratory
Under 2 pCi/L: 38%2 to 4 pCi/L: 29%4 pCi/L and above: 33%
Of 841 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 318 | 37.8% |
| 2 to 4 pCi/L | 241 | 28.7% |
| 4 pCi/L and above | 282 | 33.5% |
What these figures count
These are the 841 tests reported to CDC for Jefferson 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).
Jefferson County, Compared
Jefferson County radon figures, compared
Calculated by Radon411In Jefferson County, about 3 in 10 reported tests over the 2008 to 2017 laboratory totals (282 of 841) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 2.2 points lower. Across 99 Iowa counties pooled together, 58.5% of tests reached that level, so Jefferson County runs 25.0 points below its state.
Of 6 neighbours with a figure, 5 reported a larger share at or above 4 pCi/L and 1 a smaller one; the spread is 32.1% (Van Buren County) to 60.3% (Keokuk County). By share, Jefferson County is 96th of 99 Iowa counties with 30 or more tests for the same period.
Half the tests came in under 2.6 pCi/L and half over it; the single highest reached 59.2 pCi/L. Below the action level, 318 tests (37.8%) came in under 2 pCi/L, against 21.8% statewide, and 241 tests (28.7%) fell between 2 and 4, against 19.7% statewide.
Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 33.5% share point the same way here. USGS geology rates 100% of the county's land high radon potential. CDC also counts 23 tests taken after mitigation in Jefferson County for the same period: tests in homes where a fix was already in.
CDC's ten-year totals for Jefferson County went from 686 tests (2005 to 2014) to 841 (2008 to 2017), the share going from 38.3% to 33.5%.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Jefferson County, Geology
The ground under Jefferson County
PredictedUSGS's geologic map puts all of Jefferson 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.
Jefferson County beside the ground around it
On high-potential ground Jefferson 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; Henry County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Jefferson County, Local resources
Radon testing and mitigation in Jefferson County
Listed radon businesses with an address in Jefferson 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: Fairfield
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
Jefferson County, Questions
Questions about radon in Jefferson County
Are radon levels high in Jefferson County?
Over the 2008 to 2017 laboratory totals, 33.5% of the radon tests reported to CDC for Jefferson County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.6 pCi/L. Of 99 Iowa counties with 30 or more tests for the same period, 95 reported a higher share; pooled, the state comes to 58.5%.
Which counties border Jefferson County?
Jefferson County borders 6 counties: Henry County, Washington County, Van Buren County, Wapello County, Keokuk County and Davis County.
Products
Jefferson County, Products
Testing a home in Jefferson County
In Jefferson County, 33.5% of 841 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 Jefferson 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
Corentium Home 2 battery digital radon monitor
- C-NRPP 2024/25: Not included
- Battery
- Bluetooth
- Screen, app
Method: Alpha spectrometry
Readings: Every 60 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
Jefferson County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Jefferson County
Explore
Jefferson County, Bordering counties
Counties bordering Jefferson County
Calculated by Radon411- Radon levels in Keokuk CountyEPA zone 1
60.3%at or above 4 pCi/L
Median 5.2 pCi/L · 214 tests · 26.8 points above Jefferson County
- Radon levels in Washington CountyEPA zone 1
54.9%at or above 4 pCi/L
Median 4.6 pCi/L · 1,186 tests · 21.4 points above Jefferson County
- Radon levels in Henry CountyEPA zone 1
46.4%at or above 4 pCi/L
Median 3.4 pCi/L · 168 tests · 12.9 points above Jefferson County
- Radon levels in Davis CountyEPA zone 1
42.4%at or above 4 pCi/L
Median 3.1 pCi/L · 85 tests · 8.9 points above Jefferson County
- Radon levels in Wapello CountyEPA zone 1
35.9%at or above 4 pCi/L
Median 2.7 pCi/L · 287 tests · 2.4 points above Jefferson County
- Radon levels in Van Buren CountyEPA zone 1
32.1%at or above 4 pCi/L
Median 2.3 pCi/L · 56 tests · 1.4 points below Jefferson County
Jefferson County, Cities and towns
Cities and towns in Jefferson County
About 15,291 people live in Jefferson County by the Census Bureau's estimate for July 1, 2025, 397 fewer than in 2020 (−2.5%). That works out to 35 people per square mile of land. Fairfield alone is home to 9,220 of them, 60.3% of the total. Testing is reported here more often than across the state: CDC's 841 reported tests for 2008 to 2017 come to 55.0 for every 1,000 residents (2025 estimate), against 29.4 for Iowa.
From Fairfield to Coppock, CDC publishes no figure by town: each reads Jefferson County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Fairfield | 9,220 | −2.4% | 60.3% |
| Batavia | 419 | −3.2% | 2.7% |
| Maharishi Vedic City | 281 | +3.3% | 1.8% |
| Libertyville | 269 | −2.9% | 1.8% |
| Lockridge | 239 | −1.6% | 1.6% |
| Packwood | 180 | −2.7% | 1.2% |
| Pleasant Plain | 76 | −2.6% | 0.5% |
| Coppockextends beyond Jefferson County | 35 | −2.8% | Counted whole |
8 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 Jefferson County is counted whole, so it has no share.
Jefferson County, Homes
Homes in Jefferson County
Of Jefferson County's 7,707 homes, 70% are detached houses, against 72% across Iowa; 8% are mobile homes. Half of its homes were built before 1967, close to Iowa's 1971: 43% date from before 1960 and 15% from 2000 or later. 65% 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 | Jefferson County | Iowa |
|---|---|---|
| Housing units | 7,707 | 1,427,175 |
| Detached houses | 70% | 72% |
| In buildings of 5 or more | 6% | 14% |
| Mobile homes | 8% | 3% |
| Built before 1960 | 43% | 39% |
| Built since 2000 | 15% | 21% |
| Middle year built | 1967 | 1971 |
| Owner-occupied | 65% | 72% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.