Short-term kit
Air Chek Short-Term radon test kit you hang, lab fee included
- Lab fee included
In home: 72 to 168 hours
Locations and reports
Radon Levels in Nassau County, Florida
EPA puts Nassau County in Zone 3, its lowest radon zone, and most reported tests there come back low, though 0.0% of 90 (2023) reached 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
0.0%
18.5 pts below FL
- Nassau
- 0.0%
- Florida
- 18.5%
90 tests, 2023
Median result
0.7pCi/L
Below action level
- Nassau
- 0.7 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2023
Tests reported
90
25th of 30 by tests
- Nassau
- 90
- Broward
- 2,165
Reported to CDC before any fix, 2023
EPA radon zone
Zone 3
Lower potential
- 1
- 2
- Zone 3
1 highest, 3 lowest
EPA predicts under 2 pCi/L indoors
Rank in Florida
23 of 30
Middle half
- Nassau
- 0.0%
- Marion
- 44.5%
By share, of 30 with 30+ tests
Read a result for Nassau County
Starts at Nassau County's median, 0.7 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 0.7 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. Nassau County's median reported result, 2023.
The data
Nassau County, At a glance
Nassau County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
USGS geologic potential: Low across 95% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Nassau County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 0.0% |
| 2015 | 0.0% |
| 2016 | 0.0% |
| 2018 | 0.0% |
| 2020 | 0.0% |
| 2021 | 0.0% |
| 2022 | 0.0% |
| 2023 | 0.0% |
2023: 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
These are the 90 tests reported to CDC for Nassau 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).
Nassau County, Compared
Nassau County radon figures, compared
Calculated by Radon411Only 0 of 90 radon tests reported for Nassau County in 2023 reached 4 pCi/L (0.0%). The median result, 0.7 pCi/L, sits below 2, well under EPA's 4 pCi/L action level, and the top reported result was 1.5 pCi/L.
Across 49 Florida counties pooled together, 18.5% of tests reached that level, so Nassau County runs 18.5 points below its state. Against the national pool of 33.4%, the gap is 33.4 points lower. Its place in the state: 23rd of 30 Florida counties with 30 or more tests for the same period.
Zone 3 on EPA's map (predicted average under 2 pCi/L) and a 0.0% share point the same way here. Of 2 neighbours with a figure, all 2 reported a larger share at or above 4 pCi/L; the spread is 0.0% (Baker County) to 6.2% (Duval County).
Below the action level, 90 tests (100.0%) came in under 2 pCi/L, against 57.3% statewide, and 0 tests (0.0%) fell between 2 and 4, against 24.2% statewide. Over 3 years of annual figures the share held within 2 points, from 0.0% in 2021 to 0.0% in 2023; its peak was 0.0% in 2021. USGS geology rates 95% of the county's land low radon potential.
The busiest year on file was 2023, with 90 tests reported; the quietest, 2016, had 1.
Nassau CountyFlorida, pooled
0.0% % of tests18.5% % of tests
| Year | Tests | Nassau County, at or above 4 pCi/L | Florida, pooled |
|---|---|---|---|
| 2021 | 33 | 0.0% | 15.4% |
| 2022 | 33 | 0.0% | 22.8% |
| 2023 | 90 | 0.0% | 18.5% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Nassau County, Geology
The ground under Nassau County
PredictedUSGS's geologic map puts all of Nassau County's mapped land in one class: low radon potential. 95.1% of it lies in the area the map calls Gulf/Atlantic Lowland and Central Highland, to which USGS gives a radon index of 6, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Gulf/Atlantic Lowland and Central Highland | sand, silt, clay, gravel | Low | 6 | 95.1% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Nassau County beside the ground around it
Across Florida 7.1% of the land is rated moderate; none of Nassau County's is. Of the 4 counties that border it, 1 has more moderate-potential ground, Baker County the most at 5.8%.
The map rates the ground, not the air in any home.
Local help
Nassau County, Local resources
Radon testing and mitigation in Nassau County
- Florida’s Radon ProgramFlorida’s Radon Program, run by Florida Department of Health, licenses or certifies radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in Florida.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
Protect your family by requesting a FREE radon test kit.
- Compare kits
- Professionals in Florida77 professionals are listed in Florida.
What Florida's program says
- Phone
- 850-245-4288
- PHtoxicology@FLhealth.gov
- Licensing of radon professionals
Florida Statutes require the certification of businesses and individuals providing radon services or any other radon related activity.
What it means
Nassau County, Questions
Questions about radon in Nassau County
Are radon levels high in Nassau County?
In 2023, 0.0% of the radon tests reported to CDC for Nassau County, Florida were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.7 pCi/L. Of 30 Florida counties with 30 or more tests for the same period, 22 reported a higher share; pooled, the state comes to 18.5%.
Which counties border Nassau County?
Nassau County borders 4 counties: Duval County, FL, Charlton County, GA, Baker County, FL and Camden County, GA.
Products
Nassau County, Products
Testing a home in Nassau County
In Nassau County, 0.0% of 90 tests reported to CDC in 2023 reached 4 pCi/L, against 18.5% pooled across Florida. 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 Nassau County.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
Monitor
RM-63Pro rechargeable radon monitor with a touchscreen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Nassau County, Bordering counties
Counties bordering Nassau County
Calculated by Radon411- Radon levels in Duval County, FLEPA zone 3
6.2%at or above 4 pCi/L
Median 0.4 pCi/L · 792 tests · 6.2 points above Nassau County
- Radon levels in Baker County, FLEPA zone 3
0.0%at or above 4 pCi/L
Median 1.1 pCi/L · 48 tests · 0.0 points above Nassau County
- Radon levels in Charlton County, GAEPA zone 3
No CDC figure for 2023; its page reads it against its own neighbours.
- Radon levels in Camden County, GAEPA zone 3
No CDC figure for 2023; its page reads it against its own neighbours.
Nassau County, Cities and towns
Cities and towns in Nassau County
Nassau County is growing: the Census Bureau puts it at 106,879 residents on July 1, 2025, up 17.4% from 91,040 in 2020. That works out to 165 people per square mile of land. No town dominates: Fernandina Beach, the largest, has 13,869 residents, 13.0% of the total. Together its 3 incorporated places hold 17.6% of those residents; the other 82.4% live outside any of them. CDC's 90 reported tests for 2023 work out to 0.8 per 1,000 residents (2025 estimate), close to Florida's 0.7.
From Fernandina Beach to Callahan, CDC publishes no figure by town: each reads Nassau County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Fernandina Beach | 13,869 | +5.9% | 13.0% |
| Hilliard | 3,161 | +6.9% | 3.0% |
| Callahan | 1,830 | +18.0% | 1.7% |
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).
Nassau County, Homes
Homes in Nassau County
Of Nassau County's 43,565 homes, 67% are detached houses, against 55% across Florida; 17% are mobile homes. Much of Nassau County is recent building: 46% of its homes have gone up since 2000 and the middle year built is 1998, against 1988 for Florida. Owners live in 83% of the occupied homes (Florida: 67%), so for most households a test and a fix are their own to order.
| Homes | Nassau County | Florida |
|---|---|---|
| Housing units | 43,565 | 10,082,356 |
| Detached houses | 67% | 55% |
| In buildings of 5 or more | 9% | 25% |
| Mobile homes | 17% | 8% |
| Built before 1960 | 6% | 10% |
| Built since 2000 | 46% | 30% |
| Middle year built | 1998 | 1988 |
| Owner-occupied | 83% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.