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Radon Levels in Union County, Florida

EPA puts Union County in Zone 2, its middle radon zone, and only 3 radon tests from it are on file with CDC (2022). Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

How to test this homeFind a certified tester

  • Highest bordering

    35.2%

    Alachua County

    Alachua
    35.2%
    Columbia
    6.7%

    2 of 4 neighbours have 30+ tests, 2008 to 2017

  • Nearest county

    6.7%

    Columbia County, 19 miles

    Columbia
    6.7%
    Florida
    22.7%

    Share at 4+ pCi/L, 30 tests, 2008 to 2017

  • Ground above low

    63.8%

    56.7 pts above Florida

    Union
    63.8%
    Florida
    7.1%

    Share of land USGS rates moderate or high potential

  • Tests reported

    3

    Too few for a share

    Union
    3
    Needed
    30

    2022

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    EPA predicts 2 to 4 pCi/L indoors

Read a result for Union County

Starts at EPA's action level

4.0pCi/L

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

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 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.

Interpret this readingWhat a fix costs

The data

Union County, At a glance

Union County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Union County is a county: EPA's forecast for it as a whole is an average indoor of 2 to 4 pCi/L (75 to 150 Bq/m³). It describes no single address, and homes above EPA's are found in every zone, this one included.

USGS geologic potential: Moderate across 64% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Union County, 2022

CDC holds 3 reported tests for Union County in 2022, with a median of 5.2 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Union County beside the counties around it is how this page reads it.

What these figures count

Only 3 tests were reported to CDC for Union County over 2022, 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: 2022. Measured data period: 2005 to 2022 (every CDC figure on file).

How to read these figures

Union County, Compared

Union County radon figures, compared

Calculated by Radon411

CDC's largest figure for Union County rests on 3 tests in 2022, 3 of them at or above 4 pCi/L, so each test moves its share by 33.3 points and no rank or comparison is drawn from it. Results reached as high as 5.2 pCi/L, with a middle value of 5.2 pCi/L.

Of the counties bordering it, 2 have a figure over the 2008 to 2017 laboratory totals: Alachua County reported the largest share at or above 4 pCi/L, 35.2%, and Columbia County the smallest, 6.7%. Farther out, Duval County (46 miles away) at 1.3%, Putnam County (48 miles away) at 1.1% and Nassau County (52 miles away) at 2.0% have figures too. Pooled across 62 Florida counties, 22.7% of reported tests reached that level; across every county in the country with a figure, 35.7%.

Statewide for the same period, Marion County reported the highest share (42.9%) and St. Lucie County the lowest (0.0%). EPA's 1993 map puts Union County in Zone 2, its middle label: a predicted county average between 2 and 4 pCi/L. USGS geology rates 64% of the county's land moderate radon potential.

Florida, the United States and the counties around Union County, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedian
Florida, pooled62 counties, pooled53,79422.7%Not pooled
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled
Marion Countyhighest in the state90342.9%3.3 pCi/L
St. Lucie Countylowest in the state460.0%0.1 pCi/L
Alachua County, FLborders it2,16235.2%2.9 pCi/L
Columbia County, FLborders it306.7%1.0 pCi/L
Bradford County, FLborders it50.0%2.0 pCi/L
Baker County, FLborders it10.0%1.0 pCi/L
The nearest Florida counties to Union County with 30 or more tests, 2008 to 2017, laboratory
CountyDistanceTestsAt or above 4 pCi/LMedian
Columbia County19 mi306.7%1.0 pCi/L
Alachua County25 mi2,16235.2%2.9 pCi/L
Duval County46 mi4801.3%0.5 pCi/L
Putnam County48 mi951.1%0.1 pCi/L
Nassau County52 mi502.0%0.7 pCi/L
St. Johns County57 mi506.0%0.7 pCi/L
Marion County60 mi90342.9%3.3 pCi/L
Citrus County83 mi1629.9%1.6 pCi/L
Union County ten-year laboratory totals, against Florida's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestFlorida, pooledChange from the row before
2008 to 2017366.7%8.5 pCi/L8.5 pCi/L22.7%−33.3 points
2007 to 20162100.0%8.5 pCi/L8.5 pCi/L22.7%Level
2006 to 20152100.0%8.5 pCi/L8.5 pCi/L22.9%+33.3 points
2005 to 2014366.7%8.5 pCi/L8.5 pCi/L22.1%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Union County, Geology

The ground under Union County

Predicted

USGS's geologic map splits Union County: 63.8% of its land is moderate radon potential and 36.2% low. The map puts 63.8% of Union County in the area it calls Highland Anomalous areas and 36.2% in Gulf/Atlantic Lowland and Central Highland. USGS gives the first a radon index of 11, in the moderate band (9 to 11), and the second 6, in the low band (5 to 8).

USGS's geologic areas under Union County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Highland Anomalous areasPhosphate deposits.Moderate1163.8%
Gulf/Atlantic Lowland and Central Highlandsand, silt, clay, gravelLow636.2%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Union County beside the ground around it

Union County has more moderate-potential ground than Florida as a whole: 63.8% of its land against 7.1%. Of the 4 counties that border it, none has as large a share of moderate-potential ground; Alachua County comes nearest at 47.3%.

Share of land by USGS radon potential: Union County, the 4 counties bordering it and Florida
AreaEPA zoneLow potentialModerate potentialHigh potential
Union CountyZone 236.2%63.8%None
Bradford CountyZone 377.8%22.2%None
Columbia CountyZone 277.3%22.7%None
Baker CountyZone 394.2%5.8%None
Alachua CountyZone 252.7%47.3%None
Florida67 counties, pooled by land areaVaries89.7%7.1%None

The map rates the ground, not the air in any home.

Local help

Union County, Local resources

Radon testing and mitigation in Union County

What Florida's program says
Phone
850-245-4288
Email
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

Union County, Questions

Questions about radon in Union County

Are radon levels high in Union County?

In 2022, 100.0% of the radon tests reported to CDC for Union County, Florida were at or above 4 pCi/L, and the median reported pre-mitigation result was 5.2 pCi/L. Of the counties bordering it, 2 have a figure over the 2008 to 2017 laboratory totals: Alachua County reported the largest share at or above 4 pCi/L, 35.2%, and Columbia County the smallest, 6.7%.

Which counties border Union County?

Union County borders 4 counties: Bradford County, Columbia County, Baker County and Alachua County.

Products

Union County, Products

Testing a home in Union County

No CDC figure names Union County; the nearest county with one, Columbia County (19 miles away), reported 6.7% 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 Union County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Union County homes, compared

Explore

Union County, Bordering counties

Counties bordering Union County

Calculated by Radon411

Union County, Cities and towns

Cities and towns in Union County

Union County is growing: the Census Bureau puts it at 16,250 residents on July 1, 2025, up 5.2% from 15,442 in 2020. That works out to 67 people per square mile of land. No town dominates: Lake Butler, the largest, has 1,921 residents, 11.8% of the total. Together its 3 incorporated places hold 15.6% of those residents; the other 84.4% live outside any of them. Reported testing is thin here: 3 tests over 2022, or 0.2 for every 1,000 residents (2025 estimate), where Florida as a whole comes to 2.6.

From Lake Butler to Raiford, CDC publishes no figure by town: each reads Union County's.

The cities and towns in Union County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Lake Butler1,921−0.2%11.8%
Worthington Springs380+0.8%2.3%
Raiford226+2.3%1.4%

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).

Union County, Homes

Homes in Union County

Mobile homes are 48% of Union County's 4,772 homes and detached houses 46%, against 55% across Florida. Half of its homes were built before 1991, close to Florida's 1988: 10% date from before 1960 and 31% from 2000 or later. 74% of occupied homes are lived in by their owner (Florida: 67%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Union County, Florida, 2019 to 2023
HomesUnion CountyFlorida
Housing units4,77210,082,356
Detached houses46%55%
In buildings of 5 or more1%25%
Mobile homes48%8%
Built before 196010%10%
Built since 200031%30%
Middle year built19911988
Owner-occupied74%67%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.