What Is Radon and Why Does It Matter in Florida?
Radon is a naturally occurring radioactive gas produced by the decay of uranium in soil and rock. It seeps into buildings through foundation cracks, construction joints, and gaps around pipes. Because it's colorless and odorless, it's undetectable without testing. Radon is the second leading cause of lung cancer in the United States — responsible for approximately 21,000 deaths annually, according to the EPA — and the leading cause among non-smokers.
Florida's reputation as a low-radon state is partially accurate but can lead homeowners to dismiss the risk too quickly. The state's geology — primarily limestone karst overlain by sand — does produce lower average radon levels than the Upper Midwest or Northeast. However, certain geologic formations in North and Central Florida generate meaningfully elevated radon, and some individual Florida homes test well above the EPA action level regardless of county averages.
EPA Action Level and Florida's Average Radon Levels
The EPA recommends taking action to reduce radon when levels reach or exceed 4 picocuries per liter (pCi/L). The national average indoor radon level is approximately 1.3 pCi/L. Florida's statewide average is approximately 0.8–1.0 pCi/L, below the national average. However, averages mask meaningful county-level variation.
The Florida Department of Health has identified several counties with elevated radon potential, particularly associated with phosphate-rich geology: Alachua, Columbia, Suwannee, Levy, Marion, Citrus, Hernando, Pasco, Hillsborough, and Polk counties in Central and North Florida have documented higher median indoor radon levels than coastal South Florida. Clay and Duval counties in Northeast Florida also show elevated readings. Even in these counties, most homes test below the action level — but testing is the only way to know.
When Should You Test for Radon?
Home purchase: If you're buying a home in any Florida county identified as elevated-risk, or if the home has a basement or slab-on-grade construction, request a radon test as part of your home inspection contingency. Sellers should be asked to disclose known radon test results under Florida's seller disclosure requirements, but many have never tested.
Existing homes: The EPA recommends that all homes be tested for radon at least once. If your home has never been tested, testing is inexpensive and provides important information about your household's long-term cancer risk.
After major renovations: Sealing cracks, adding a room addition, or significantly changing a home's air sealing can change radon dynamics. Re-test after major structural work.
Testing Methods: DIY vs. Professional
DIY short-term tests ($15–$30) use activated charcoal canisters placed in the lowest livable area of the home (usually the first floor in Florida, since basements are rare) for 48–96 hours, then mailed to an accredited laboratory. Results are returned in 1–2 weeks. Short-term tests are useful for initial screening but can be influenced by weather conditions, home ventilation patterns, and season.
Long-term tests ($25–$50) use electret ion chambers or alpha track detectors placed for 90 days to one year. They provide a more accurate picture of average annual exposure, which is more relevant to health risk than any single short-term measurement.
Professional testing ($100–$300) uses continuous electronic radon monitors that record hourly readings, provide tamper evidence, and generate a detailed report. This is the appropriate standard for real estate transactions — most real estate attorneys in elevated-risk counties recommend professional testing over DIY kits for purchase decisions.
Florida does not currently require a state license specifically for radon testers, but look for professionals certified through the National Radon Proficiency Program (NRPP) or National Radon Safety Board (NRSB).
Mitigation: What Happens If Your Home Tests High?
If your home tests at or above 4 pCi/L, radon mitigation is recommended. The most effective and common technique is sub-slab depressurization (SSD), also called "active soil depressurization." A licensed contractor installs a pipe through the slab floor and a continuously running fan that draws radon-laden air from beneath the slab and vents it safely above the roofline. The system operates 24/7 and typically reduces radon levels by 50–99%.
In Florida's slab-on-grade homes (the dominant construction type), SSD installation typically costs $800–$1,800. Homes with crawl spaces use a different approach — crawl space encapsulation with a fan system — costing $1,500–$2,500. Ongoing operating costs are minimal: the fan uses about as much electricity as a light bulb ($50–$100/year).
After mitigation, test again (wait 24 hours after installation, then test for 48+ hours) to confirm the system is working. A well-installed SSD system should bring levels below 2 pCi/L in most Florida homes.
Finding a Florida Radon Contractor
The Florida Department of Health maintains a list of licensed radon mitigation businesses at floridahealth.gov/environmental-health/radon. The EPA also recommends seeking contractors certified through the NRPP or NRSB. Get at least two quotes — pricing and system design quality vary. Be wary of contractors who promise specific radon level reductions before testing the system.