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
Locations and reports
Radon Levels in Hardin County, Illinois
EPA puts Hardin County in Zone 2, its middle radon zone, and only 6 radon tests from it are on file with CDC (2014). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Highest bordering
20.7%
Saline County
- Saline
- 20.7%
1 of 6 neighbours have 30+ tests, 2008 to 2017
Nearest county
20.7%
Saline County, 22 miles
- Saline
- 20.7%
- Illinois
- 43.1%
Share at 4+ pCi/L, 82 tests, 2008 to 2017
Ground above low
100.0%
0.9 pts above Illinois
- Hardin
- 100.0%
- Illinois
- 99.1%
Share of land USGS rates moderate or high potential
Tests reported
11
Too few for a share
- Hardin
- 11
- Needed
- 30
2006 to 2015, laboratory
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Read a result for Hardin County
Starts at EPA's action level
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.0 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.
The data
Hardin County, At a glance
Hardin County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Hardin County is a
USGS geologic potential: Moderate across 100% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Hardin County, 2014
CDC holds 6 reported tests for Hardin County in 2014, with a median of 1.3 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Hardin County beside the counties around it is how this page reads it.
What these figures count
Only 6 tests were reported to CDC for Hardin County over 2014, and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.
Measured: CDC tracking data. Figure above: 2014. Measured data period: 2005 to 2017 (every CDC figure on file).
Hardin County, Compared
Hardin County radon figures, compared
Calculated by Radon411CDC's largest figure for Hardin County rests on 11 tests over the 2006 to 2015 laboratory totals, 4 of them at or above 4 pCi/L, so each test moves its share by 9.1 points and no rank or comparison is drawn from it. Results reached as high as 7.1 pCi/L, with a middle value of 3.4 pCi/L.
Saline County, the one bordering county with a figure over the 2008 to 2017 laboratory totals, reported 20.7% of its tests at or above 4 pCi/L. Farther out, Massac County (32 miles away) at 15.2%, Johnson County (34 miles away) at 14.6% and Williamson County (39 miles away) at 13.3% have figures too. Pooled across 102 Illinois counties, 43.1% of reported tests reached that level; across every county in the country with a figure, 35.7%.
Statewide for the same period, Stark County reported the highest share (80.5%) and Williamson County the lowest (13.3%). EPA's 1993 map puts Hardin County in Zone 2, its middle label: a predicted county average between 2 and 4 pCi/L. USGS geology rates 100% of the county's land moderate radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Hardin County, Geology
The ground under Hardin County
PredictedUSGS's geologic map puts all of Hardin County's mapped land in one class: moderate radon potential. 98.5% of it lies in the area the map calls Shawnee Hills Section, to which USGS gives a radon index of 10, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Shawnee Hills Section | Unglaciated Ordovician to Pennsylvanian limestone, sandstone, and shale. | Moderate | 10 | 98.5% |
| Mississippian Plateau | Mississippian marine limestones, dolomites, marine sandstones, siltstones, and shales. | Moderate | 11 | 1.4% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Hardin County beside the ground around it
Across Illinois 64.5% of the land is rated high; none of Hardin County's is. Of the 6 counties that border it, none has as large a share of moderate-potential ground; Crittenden County, KY comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Hardin County, Local resources
Radon testing and mitigation in Hardin County
- IEMA-OHS Radon ProgramIEMA-OHS Radon Program, run by Illinois Emergency Management Agency and Office of Homeland Security, licenses or certifies radon professionals and states the rule for disclosing radon when a home is sold, and answers questions about testing and mitigation in Illinois.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsAsk the program whether it has free or discounted kits, or compare kits you can buy.
- Compare kits
- Professionals in Illinois339 professionals are listed in Illinois.
What Illinois's program says
- Phone
- (800) 325-1245
- Licensing of radon professionals
The Agency also licenses and regulates the individuals who provide radon measurement and mitigation to the public.
- Disclosure when a home is sold or rented
Illinois Radon Awareness Act - This is the legislation that requires the seller to provide to the buyer of any interest in residential real property the IEMA-OHS pamphlet entitled "Radon Testing Guidelines for Real Estate Transactions" and the Illinois Disclosure of Information on Radon Hazards.
What it means
Hardin County, Questions
Questions about radon in Hardin County
Are radon levels high in Hardin County?
In 2014, 0.0% of the radon tests reported to CDC for Hardin County, Illinois were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.3 pCi/L. Saline County, the one bordering county with a figure over the 2008 to 2017 laboratory totals, reported 20.7% of its tests at or above 4 pCi/L.
Which counties border Hardin County?
Hardin County borders 6 counties: Crittenden County, KY, Gallatin County, IL, Livingston County, KY, Union County, KY, Pope County, IL and Saline County, IL.
Products
Hardin County, Products
Testing a home in Hardin County
No CDC figure names Hardin County; the nearest county with one, Saline County (22 miles away), reported 20.7% of its tests at or above 4 pCi/L over the 2008 to 2017 laboratory totals, the only reading nearby until a test of this home. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Hardin County; a long-term test tells the year-round average.
Test kits and monitors3
See every kit and monitor
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
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
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Hardin County, Bordering counties
Counties bordering Hardin County
Calculated by Radon411- Radon levels in Gallatin County, ILEPA zone 2
33.3%at or above 4 pCi/L
Median 2.0 pCi/L · 6 tests
- Radon levels in Crittenden County, KYEPA zone 2
25.0%at or above 4 pCi/L
Median 1.6 pCi/L · 8 tests
- Radon levels in Union County, KYEPA zone 2
25.0%at or above 4 pCi/L
Median 1.6 pCi/L · 8 tests
- Radon levels in Saline County, ILEPA zone 2
20.7%at or above 4 pCi/L
Median 1.7 pCi/L · 82 tests
- Radon levels in Livingston County, KYEPA zone 2
0.0%at or above 4 pCi/L
Median 1.3 pCi/L · 11 tests
- Radon levels in Pope County, ILEPA zone 2
0.0%at or above 4 pCi/L
Median 1.8 pCi/L · 7 tests
Hardin County, Cities and towns
Cities and towns in Hardin County
About 3,588 people live in Hardin County by the Census Bureau's estimate for July 1, 2025, 66 fewer than in 2020 (−1.8%). That works out to 20 people per square mile of land. Its largest town, Rosiclare, has 977 residents, 27.2% of the total. Together its 3 incorporated places hold 39.7% of those residents; the other 60.3% live outside any of them. Reported testing is thin here: 11 tests over 2006 to 2015, or 3.1 for every 1,000 residents (2025 estimate), where Illinois as a whole comes to 7.8.
From Rosiclare to Cave-In-Rock, CDC publishes no figure by town: each reads Hardin County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Rosiclare | 977 | −2.2% | 27.2% |
| Elizabethtown | 225 | −2.2% | 6.3% |
| Cave-In-Rock | 222 | −2.6% | 6.2% |
3 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).
Hardin County, Homes
Homes in Hardin County
Of Hardin County's 2,285 homes, 71% are detached houses, against 58% across Illinois; 20% are mobile homes. Half of its homes were built before 1973, close to Illinois' 1970: 35% date from before 1960 and 12% from 2000 or later. Owners live in 81% of the occupied homes (Illinois: 67%), so for most households a test and a fix are their own to order.
| Homes | Hardin County | Illinois |
|---|---|---|
| Housing units | 2,285 | 5,443,501 |
| Detached houses | 71% | 58% |
| In buildings of 5 or more | 0% | 22% |
| Mobile homes | 20% | 2% |
| Built before 1960 | 35% | 38% |
| Built since 2000 | 12% | 16% |
| Middle year built | 1973 | 1970 |
| Owner-occupied | 81% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.