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Radon Levels in Collier County, Florida

EPA puts Collier County in Zone 3, its lowest radon zone, and 22.7% of its 1,607 reported radon tests (2023) 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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    22.7%

    4.2 pts above FL

    Collier
    22.7%
    Florida
    18.5%

    1,607 tests, 2023

  • Median result

    2.3pCi/L

    Below action level

    Collier
    2.3 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    1,607

    3rd of 30 by tests

    Collier
    1,607
    Broward
    2,165

    Reported to CDC before any fix, 2023

  • EPA radon zone

    Zone 3

    Lower potential

    1. 1
    2. 2
    3. Zone 3

    1 highest, 3 lowest

    EPA predicts under 2 pCi/L indoors

  • Rank in Florida

    5 of 30

    Top quarter

    Collier
    22.7%
    Marion
    44.5%

    By share, of 30 with 30+ tests

Read a result for Collier County

Starts at Collier County's median, 2.3 pCi/L

2.3pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 2.3 pCi/L

Between 2 and 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 between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Collier County's median reported result, 2023.

Interpret this readingWhat a fix costs

The data

Collier County, At a glance

Collier County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

is EPA's lowest class, and its forecast for Collier County as a whole is an average indoor of less than 2 pCi/L (less than 75 Bq/m³). A low zone clears no address in it: homes above EPA's turn up in all three zones.

USGS geologic potential: Low across 97% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Collier County, 2023

Share of reported tests at or above 4 pCi/L, by year, Collier County
Share of reported tests at or above 4 pCi/L, by year, Collier County
YearShare of reported tests at or above 4 pCi/L
201428.8%
201531.3%
201623.5%
201725.0%
201824.2%
201923.5%
202028.1%
202122.7%
202225.0%
202322.7%

2023: 22.7%. Across these years the share ran from 22.7% to 31.3%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 1,607 tests reported to CDC for Collier 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).

How to read these figures

Collier County, Compared

Collier County radon figures, compared

Calculated by Radon411

Collier County's 1,607 reported tests in 2023 had a middle value of 2.3 pCi/L and a maximum of 25.2 pCi/L, and 22.7% reached 4 pCi/L. Florida as a whole (49 Florida counties, pooled) comes to 18.5%: 4.2 points lower than here.

Among its state's counties it ranks 5th of 30 Florida counties with 30 or more tests for the same period. Statewide for the same period, Marion County reported the highest share (44.5%) and Clay County the lowest (0.0%).

Below the action level, 650 tests (40.4%) came in under 2 pCi/L, against 57.3% statewide, and 593 tests (36.9%) fell between 2 and 4, against 24.2% statewide. The busiest year on file was 2022, with 8,358 tests reported; the quietest, 2023, had 1,607.

EPA's 1993 zone map puts Collier County in Zone 3, a predicted county average under 2 pCi/L. USGS geology rates 97% of the county's land low radon potential.

Next door, the shares run from 9.4% in Broward County to 39.6% in Miami-Dade County, with Lee County and Broward County below Collier County. Over 10 years of annual figures the share fell 6.1 points, from 28.8% in 2014 to 22.7% in 2023; its peak was 31.3% in 2015.

CDC also counts 311 tests taken after mitigation in Collier County for the same period: tests in homes where a fix was already in.

Share of reported tests at or above 4 pCi/L by year, Collier County against Florida2014 to 2023, years with 30 or more tests: Collier County 28.8% to 22.7%, the state's pooled share 18.5% in 2023.
Collier CountyFlorida, pooled
Share of reported tests at or above 4 pCi/L by year, Collier County against Florida: data table
YearTestsCollier County, at or above 4 pCi/LFlorida, pooled
20143,09028.8%25.7%
20153,06931.3%26.5%
20162,33423.5%24.3%
20172,39025.0%21.7%
20182,30124.2%23.5%
20192,63623.5%29.6%
20203,00428.1%23.2%
20214,15522.7%15.4%
20228,35825.0%22.8%
20231,60722.7%18.5%
Collier County against Florida, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Collier County
Collier County1,60722.7%2.3 pCi/LThis county
Florida, pooled49 counties, pooled16,58918.5%Not pooled−4.2 points
United States, pooled642 counties, pooled128,74033.4%Not pooled+10.7 points
Marion Countyhighest in the state18244.5%3.6 pCi/L+21.8 points
Clay Countylowest in the state360.0%1.0 pCi/L−22.7 points
Miami-Dade County, FLborders it1,91939.6%2.8 pCi/L+16.9 points
Lee County, FLborders it1,22420.3%2.2 pCi/L−2.4 points
Monroe County, FLborders it812.5%0.9 pCi/L−10.2 points
Broward County, FLborders it2,1659.4%1.7 pCi/L−13.3 points
Hendry County, FLborders it30.0%1.3 pCi/L−22.7 points
Where Collier County's reported results fell, 2023, beside Florida and the United States
ResultCollier County testsCollier County shareFlorida shareU.S. shareAgainst Florida
Under 2 pCi/L65040.4%57.3%41.4%−16.9 points
2 to 4 pCi/L59336.9%24.2%25.2%+12.7 points
4 pCi/L and above36422.7%18.5%33.4%+4.2 points
Collier County ranked among the 30 Florida counties with 30 or more tests, by share at or above 4 pCi/L, 2023
CountyRankTestsAt or above 4 pCi/LMedian
Marion County1 of 3018244.5%3.6 pCi/L
Palm Beach County2 of 301,52640.1%3.0 pCi/L
Miami-Dade County3 of 301,91939.6%2.8 pCi/L
Charlotte County4 of 309131.9%2.9 pCi/L
Collier County5 of 301,60722.7%2.3 pCi/L
Alachua County6 of 3065921.4%2.4 pCi/L
Lee County7 of 301,22420.3%2.2 pCi/L
Leon County8 of 301,19619.1%1.8 pCi/L
Gadsden County9 of 309614.6%1.3 pCi/L
Sarasota County10 of 3049612.3%1.6 pCi/L
Polk County11 of 3013611.0%1.1 pCi/L
Collier County radon tests by year, against Florida's pooled share
YearTestsAt or above 4 pCi/LMedianHighestFlorida, pooledChange from the row before
20231,60722.7%2.3 pCi/L25.2 pCi/L18.5%−2.3 points
20228,35825.0%2.4 pCi/L26.2 pCi/L22.8%+2.3 points
20214,15522.7%2.3 pCi/L46.0 pCi/L15.4%−5.4 points
20203,00428.1%2.4 pCi/L268.0 pCi/L23.2%+4.6 points
20192,63623.5%2.3 pCi/L43.0 pCi/L29.6%−0.7 points
20182,30124.2%2.3 pCi/L32.2 pCi/L23.5%−0.8 points
20172,39025.0%2.4 pCi/L35.1 pCi/L21.7%+1.5 points
20162,33423.5%2.2 pCi/L76.5 pCi/L24.3%−7.8 points
20153,06931.3%2.6 pCi/L48.0 pCi/L26.5%+2.5 points
20143,09028.8%2.6 pCi/L28.2 pCi/L25.7%First on file

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

Collier County, Geology

The ground under Collier County

Predicted

USGS's geologic map puts all of Collier County's mapped land in one class: low radon potential. 96.9% 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).

USGS's geologic areas under Collier County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Gulf/Atlantic Lowland and Central Highlandsand, silt, clay, gravelLow696.9%

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

Collier County beside the ground around it

Across Florida 7.1% of the land is rated moderate; none of Collier County's is. Of the 5 counties that border it, 1 has more moderate-potential ground, Miami-Dade County the most at 17.5%.

Share of land by USGS radon potential: Collier County, the 5 counties bordering it and Florida
AreaEPA zoneLow potentialModerate potentialHigh potential
Collier CountyZone 396.9%NoneNone
Hendry CountyZone 3100%NoneNone
Lee CountyZone 383.7%NoneNone
Broward CountyZone 399.9%NoneNone
Miami-Dade CountyZone 279.5%17.5%None
Monroe CountyZone 370.2%NoneNone
Florida67 counties, pooled by land areaVaries89.7%7.1%None

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

Local help

Collier County, Local resources

Radon testing and mitigation in Collier County

Listed radon businesses with an address in Collier County:

Listed radon professionals by town: Naples

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

Collier County, Questions

Questions about radon in Collier County

Are radon levels high in Collier County?

In 2023, 22.7% of the radon tests reported to CDC for Collier County, Florida were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.3 pCi/L. Of 30 Florida counties with 30 or more tests for the same period, 4 reported a higher share; pooled, the state comes to 18.5%.

Which counties border Collier County?

Collier County borders 5 counties: Hendry County, Lee County, Broward County, Miami-Dade County and Monroe County.

Products

Collier County, Products

Testing a home in Collier County

In Collier County, 22.7% of 1,607 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 Collier County.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Collier County homes, compared

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Collier County, Bordering counties

Counties bordering Collier County

Calculated by Radon411

Collier County, Cities and towns

Cities and towns in Collier County

Collier County is growing: the Census Bureau puts it at 417,131 residents on July 1, 2025, up 10.5% from 377,327 in 2020. That works out to 209 people per square mile of land. No town dominates: Naples, the largest, has 20,114 residents, 4.8% of the total. Together its 3 incorporated places hold 8.9% of those residents; the other 91.1% live outside any of them. Testing is reported here more often than across the state: CDC's 1,607 reported tests for 2023 come to 3.9 for every 1,000 residents (2025 estimate), against 0.7 for Florida.

From Naples to Everglades, CDC publishes no figure by town: each reads Collier County's.

The cities and towns in Collier County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Naples20,114+5.1%4.8%
Marco Island16,421+4.2%3.9%
Everglades399+10.8%Under 0.1%

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).

Collier County, Homes

Homes in Collier County

Collier County has 234,732 homes, and many share a building: 36% are in buildings of five or more, 42% are detached houses, against 55% across Florida. Much of Collier County is recent building: 40% of its homes have gone up since 2000 and the middle year built is 1996, against 1988 for Florida. Owners live in 76% of the occupied homes (Florida: 67%), so for most households a test and a fix are their own to order.

Homes in Collier County, Florida, 2019 to 2023
HomesCollier CountyFlorida
Housing units234,73210,082,356
Detached houses42%55%
In buildings of 5 or more36%25%
Mobile homes5%8%
Built before 19602%10%
Built since 200040%30%
Middle year built19961988
Owner-occupied76%67%

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