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 Cobb County, Georgia
EPA puts Cobb County in Zone 1, its highest radon zone, and 16.3% of its 3,315 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
16.3%
8.5 pts below GA
- Cobb
- 16.3%
- Georgia
- 24.8%
3,315 tests, 2008 to 2017
Median result
1.9pCi/L
Below action level
- Cobb
- 1.9 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
3,315
4th of 57 by tests
- Cobb
- 3,315
- Fulton
- 4,858
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 Georgia
48 of 57
Lowest quarter
- Cobb
- 16.3%
- Barrow
- 48.3%
By share, of 57 with 30+ tests
Read a result for Cobb County
Starts at Cobb County's median, 1.9 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 1.9 pCi/L
Below 2 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is below 2 pCi/L, the level at which EPA says a fix should be considered. Cobb County's median reported result, 2008 to 2017.
The data
Cobb County, At a glance
Cobb County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Cobb County in
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 Cobb County, 2008 to 2017, laboratory
Under 2 pCi/L: 53%2 to 4 pCi/L: 31%4 pCi/L and above: 16%
Of 3,315 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 1,751 | 52.8% |
| 2 to 4 pCi/L | 1,022 | 30.8% |
| 4 pCi/L and above | 542 | 16.3% |
What these figures count
These are the 3,315 tests reported to CDC for Cobb 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).
Cobb County, Compared
Cobb County radon figures, compared
Calculated by Radon411Cobb County's 3,315 reported tests over the 2008 to 2017 laboratory totals had a middle value of 1.9 pCi/L and a maximum of 28.8 pCi/L, and 16.3% reached 4 pCi/L. Georgia as a whole (129 Georgia counties, pooled) comes to 24.8%: 8.5 points higher than here.
Among its state's counties it ranks 48th of 57 Georgia counties with 30 or more tests for the same period. Statewide for the same period, Barrow County reported the highest share (48.3%) and Richmond County the lowest (0.0%).
Below the action level, 1,751 tests (52.8%) came in under 2 pCi/L, against 44.0% statewide, and 1,022 tests (30.8%) fell between 2 and 4, against 31.2% statewide. CDC's ten-year totals for Cobb County went from 2,542 tests (2005 to 2014) to 3,315 (2008 to 2017), the share going from 14.8% to 16.3%.
EPA's 1993 zone map puts Cobb County in Zone 1, a predicted county average above 4 pCi/L. USGS geology rates 100% of the county's land moderate radon potential.
Next door, the shares run from 17.6% in Cherokee County to 47.3% in Douglas County.
CDC also counts 335 tests taken after mitigation in Cobb 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.
Cobb County, Geology
The ground under Cobb County
PredictedUSGS's geologic map puts all of Cobb County's mapped land in one class: moderate radon potential. All of it lies in the area the map calls Georgiabama Thrust Stack (South), to which USGS gives a radon index of 9, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Georgiabama Thrust Stack (South) | Schist, amphibolite and granite. | Moderate | 9 | 100% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Cobb County beside the ground around it
Cobb County has more moderate-potential ground than Georgia as a whole: 100% of its land against 26.5%. Of the 5 counties that border it, none has as large a share of moderate-potential ground; Douglas County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Cobb County, Local resources
Radon testing and mitigation in Cobb County
- Georgia's radon programGeorgia Attorney General's Consumer Protection DivisionGeorgia's radon program does not license radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in Georgia.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
A kit costs $15.00 if mailed or $10.00 if picked up at a participating County Extension office.
- Compare kits
- Professionals in Georgia3 professionals are listed in Georgia.
What Georgia's program says
- Licensing of radon professionals
There are no laws mandating a mitigator receive certification in Georgia, however, many mitigators choose to get certified by one of two national programs.
What it means
Cobb County, Questions
Questions about radon in Cobb County
Are radon levels high in Cobb County?
Over the 2008 to 2017 laboratory totals, 16.3% of the radon tests reported to CDC for Cobb County, Georgia were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.9 pCi/L. Of 57 Georgia counties with 30 or more tests for the same period, 47 reported a higher share; pooled, the state comes to 24.8%.
Which counties border Cobb County?
Cobb County borders 5 counties: Fulton County, Paulding County, Douglas County, Cherokee County and Bartow County.
Products
Cobb County, Products
Testing a home in Cobb County
In Cobb County, 16.3% of 3,315 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 24.8% pooled across Georgia. In Zone 1 the year-round level in Cobb 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
Cobb County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Cobb County
Explore
Cobb County, Bordering counties
Counties bordering Cobb County
Calculated by Radon411- Radon levels in Douglas CountyEPA zone 2
47.3%at or above 4 pCi/L
Median 3.7 pCi/L · 355 tests · 31.0 points above Cobb County
- Radon levels in Paulding CountyEPA zone 2
26.0%at or above 4 pCi/L
Median 2.3 pCi/L · 289 tests · 9.7 points above Cobb County
- Radon levels in Bartow CountyEPA zone 2
24.9%at or above 4 pCi/L
Median 2.2 pCi/L · 177 tests · 8.6 points above Cobb County
- Radon levels in Fulton CountyEPA zone 1
20.8%at or above 4 pCi/L
Median 2.2 pCi/L · 4,858 tests · 4.5 points above Cobb County
- Radon levels in Cherokee CountyEPA zone 2
17.6%at or above 4 pCi/L
Median 2.0 pCi/L · 1,154 tests · 1.3 points above Cobb County
Cobb County, Cities and towns
Cities and towns in Cobb County
The Census Bureau estimates 793,345 residents in Cobb County for July 1, 2025, 26,960 more than in 2020 (+3.5%). Packed into its land, that is 2,335 people per square mile. Roswell, the largest place on its list (91,505 residents in all), extends beyond Cobb County, so no share of the total is worked out for it. Testing is reported here more often than across the state: CDC's 3,315 reported tests for 2008 to 2017 come to 4.2 for every 1,000 residents (2025 estimate), against 2.7 for Georgia.
From Roswell to Austell, CDC publishes no figure by town: each reads Cobb County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Roswellextends beyond Cobb County | 91,505 | −1.6% | Counted whole |
| Marietta | 63,574 | +4.1% | 8.0% |
| Smyrna | 57,513 | +2.4% | 7.2% |
| Kennesaw | 37,970 | +13.8% | 4.8% |
| Acworth | 22,925 | +2.2% | 2.9% |
| Powder Springs | 21,004 | +24.2% | 2.6% |
| Austellextends beyond Cobb County | 8,339 | +6.2% | Counted whole |
7 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 Cobb County is counted whole, so it has no share.
Cobb County, Homes
Homes in Cobb County
Of Cobb County's 311,556 homes, 66% are detached houses, against 66% across Georgia; 22% are in buildings of five or more homes. Half of its homes were built before 1989, close to Georgia's 1991: 6% date from before 1960 and 29% from 2000 or later. 67% of occupied homes are lived in by their owner (Georgia: 65%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Cobb County | Georgia |
|---|---|---|
| Housing units | 311,556 | 4,483,873 |
| Detached houses | 66% | 66% |
| In buildings of 5 or more | 22% | 16% |
| Mobile homes | 1% | 8% |
| Built before 1960 | 6% | 12% |
| Built since 2000 | 29% | 33% |
| Middle year built | 1989 | 1991 |
| Owner-occupied | 67% | 65% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.