Short-term kitKidde
442020 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 3 days
Locations and reports
Radon Levels in Alexander County, Illinois
EPA puts Alexander County in Zone 3, its lowest radon zone, and only 3 radon tests from it are on file with CDC (2017). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Highest bordering
35.2%
Cape Girardeau County
- Cape Girardeau
- 35.2%
- Union
- 25.3%
3 of 6 neighbours have 30+ tests, 2008 to 2017
Nearest county
25.3%
Union County, 20 miles
- Union
- 25.3%
- Illinois
- 43.1%
Share at 4+ pCi/L, 87 tests, 2008 to 2017
Ground above low
54.6%
44.5 pts below Illinois
- Alexander
- 54.6%
- Illinois
- 99.1%
Share of land USGS rates moderate or high potential
Tests reported
15
Too few for a share
- Alexander
- 15
- Needed
- 30
2006 to 2015, laboratory
EPA radon zone
Zone 3
Lower potential
- 1
- 2
- Zone 3
1 highest, 3 lowest
EPA predicts under 2 pCi/L indoors
Read a result for Alexander 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
Alexander County, At a glance
Alexander County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
USGS geologic potential: Moderate across 55% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Alexander County, 2017
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 0.0% |
| 2017 | 0.0% |
2017: 0.0%. Across these years the share ran from 0.0% to 0.0%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
Only 3 tests were reported to CDC for Alexander County over 2017, 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: 2017. Measured data period: 2005 to 2017 (every CDC figure on file).
Alexander County, Compared
Alexander County radon figures, compared
Calculated by Radon411CDC's largest figure for Alexander County rests on 15 tests over the 2006 to 2015 laboratory totals, 5 of them at or above 4 pCi/L, so each test moves its share by 6.7 points and no rank or comparison is drawn from it. Results reached as high as 11.6 pCi/L, with a middle value of 1.3 pCi/L.
Of the counties bordering it, 3 have a figure over the 2008 to 2017 laboratory totals: Cape Girardeau County, MO reported the largest share at or above 4 pCi/L, 35.2%, and Union County the smallest, 25.3%, with Scott County, MO at 29.4% between. Farther out, Johnson County (31 miles away) at 14.6%, Massac County (35 miles away) at 15.2% and Jackson County (41 miles away) at 28.5% 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 Alexander County in Zone 3, its lowest label: a predicted county average under 2 pCi/L. USGS geology rates 55% of the county's land moderate radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Alexander County, Geology
The ground under Alexander County
PredictedUSGS's geologic map splits Alexander County: 54.6% of its land is moderate radon potential and 45.4% low. The map puts 54.5% of Alexander County in the area it calls Shawnee Hills Section and 45.2% in Coastal Plains Province. USGS gives the first a radon index of 10, in the moderate band (9 to 11), and the second 5, in the low band (5 to 8).
| 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 | 54.5% |
| Coastal Plains Province | Tertiary-Quaternary sandstone, shale, and alluvium. | Low | 5 | 45.2% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Alexander County beside the ground around it
Across Illinois 64.5% of the land is rated high; none of Alexander County's is. Of the 6 counties that border it, 2 have more moderate-potential ground, Union County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Alexander County, Local resources
Radon testing and mitigation in Alexander 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
Alexander County, Questions
Questions about radon in Alexander County
Are radon levels high in Alexander County?
In 2017, 0.0% of the radon tests reported to CDC for Alexander County, Illinois were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.0 pCi/L. Of the counties bordering it, 3 have a figure over the 2008 to 2017 laboratory totals: Cape Girardeau County, MO reported the largest share at or above 4 pCi/L, 35.2%, and Union County the smallest, 25.3%, with Scott County, MO at 29.4% between.
Which counties border Alexander County?
Alexander County borders 6 counties: Pulaski County, IL, Scott County, MO, Ballard County, KY, Cape Girardeau County, MO, Union County, IL and Mississippi County, MO.
Products
Alexander County, Products
Testing a home in Alexander County
No CDC figure names Alexander County; the nearest county with one, Union County (20 miles away), reported 25.3% 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. Zone 3 is the lowest label, yet homes at or above 4 pCi/L occur in every zone: a short-term kit (2 to 90 days) is the quick first check in Alexander County.
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
MonitorSafetySiren
Pro4 plug-in radon detector with a display and alarm
- C-NRPP 2024/25: Not included
- Plug-in
- Alarm
- Screen
First reading: Within 48 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Alexander County, Bordering counties
Counties bordering Alexander County
Calculated by Radon41135.2%at or above 4 pCi/L
Median 2.8 pCi/L · 253 tests
- Radon levels in Scott County, MOEPA zone 3
29.4%at or above 4 pCi/L
Median 2.2 pCi/L · 51 tests
- Radon levels in Union County, ILEPA zone 2
25.3%at or above 4 pCi/L
Median 1.9 pCi/L · 87 tests
- Radon levels in Pulaski County, ILEPA zone 3
18.2%at or above 4 pCi/L
Median 2.0 pCi/L · 11 tests
- Radon levels in Ballard County, KYEPA zone 3
0.0%at or above 4 pCi/L
Median 1.4 pCi/L · 4 tests
- Radon levels in Mississippi County, MOEPA zone 3
0.0%at or above 4 pCi/L
Median 0.1 pCi/L · 4 tests
Alexander County, Cities and towns
Cities and towns in Alexander County
Alexander County has been losing residents: from 5,172 in 2020 to 4,570 on July 1, 2025, a fall of 11.6% by the Census Bureau's estimates. That works out to 19 people per square mile of land. Its largest town, Cairo, has 1,515 residents, 33.2% of the total. Together its 5 incorporated places hold 55.6% of those residents; the other 44.4% live outside any of them. Reported testing is thin here: 15 tests over 2006 to 2015, or 3.3 for every 1,000 residents (2025 estimate), where Illinois as a whole comes to 7.8.
From Cairo to Thebes, CDC publishes no figure by town: each reads Alexander County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Cairo | 1,515 | −11.8% | 33.2% |
| Tamms | 373 | −11.2% | 8.2% |
| East Cape Girardeau | 251 | −11.6% | 5.5% |
| McClure | 223 | −11.9% | 4.9% |
| Thebes | 181 | −11.7% | 4.0% |
5 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).
Alexander County, Homes
Homes in Alexander County
Alexander County is a place of houses on their own lots: 76% of its 2,964 homes are detached single-family houses, against 58% across Illinois. Half of its homes were built before 1969, close to Illinois' 1970: 37% date from before 1960 and 10% from 2000 or later. Owners live in 78% of the occupied homes (Illinois: 67%), so for most households a test and a fix are their own to order.
| Homes | Alexander County | Illinois |
|---|---|---|
| Housing units | 2,964 | 5,443,501 |
| Detached houses | 76% | 58% |
| In buildings of 5 or more | 8% | 22% |
| Mobile homes | 14% | 2% |
| Built before 1960 | 37% | 38% |
| Built since 2000 | 10% | 16% |
| Middle year built | 1969 | 1970 |
| Owner-occupied | 78% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.