Is radon a problem in Naples and Southwest Florida?

It can be. Collier County is in the EPA's lowest predicted zone (Zone 3), but the EPA is explicit that elevated radon has been found in all three zones and every home should be tested regardless of zone. Florida's own Department of Health data shows about 1 in 5 Florida homes tests above the action level — including slab homes and high-rise condos — so a Naples home should be tested, not assumed safe.

What radon level is dangerous?

The EPA recommends fixing a home at 4.0 pCi/L or higher, and says to consider fixing between 2 and 4 pCi/L. There is no completely safe level — radon is the #1 cause of lung cancer among non-smokers and the #2 cause overall, behind only smoking.

How do I test for radon, and are free kits available?

You can use a DIY kit (short-term tests run 2–90 days; all tests should run at least 48 hours) or hire a Florida-certified radon professional, which is required for paid testing in a transaction. The Florida Department of Health offers free test kits when in stock — as of 2026 they were temporarily out, with low-cost kits available from sosradon.org as an alternative.

How much does radon mitigation cost?

A sub-slab depressurization system — a pipe and continuous fan that vents radon from beneath the slab above the roofline — typically runs roughly $800–$2,500 (often around $1,200–$1,500) from a Florida-certified mitigator, and can cut radon by 50–99%. Retest after install and about every two years.

Radon in Naples & SWFL Homes: A Buyer's Guide (2026)

Q: Does Florida law require radon disclosure?

Yes. Florida Statute 404.056(5) requires a radon notice in real estate contracts and most leases. It reads, in part: 'Radon is a naturally occurring radioactive gas that, when it has accumulated in a building in sufficient quantities, may present health risks to persons who are exposed to it over time.' The notice is built into standard Florida Realtors contracts.

Radon doesn’t get the attention that flood and hurricanes do in Southwest Florida — which is exactly why it’s worth understanding. It’s an invisible, odorless gas, it’s the second-leading cause of lung cancer, and the myth that “Florida homes don’t have radon because there are no basements” is flat wrong. Here’s what a Naples buyer actually needs to know.

The 60-second version

Radon is the #1 cause of lung cancer among non-smokers (#2 overall) — about 21,000 U.S. deaths a year.
1 in 5 Florida homes tests above the EPA action level — including slab homes and high-rise condos.
Collier is the EPA's lowest zone, but the EPA says test every home regardless of zone.
Florida law (404.056) requires a radon disclosure in real estate contracts.
Test during your inspection period; mitigation (if needed) is a routine, affordable fix.

What radon is — and why it matters

Radon is a naturally occurring radioactive gas produced as uranium and radium break down in soil and rock. Because the air pressure inside a house is usually lower than the soil beneath it, your home acts like a vacuum, drawing radon up through cracks and openings in the foundation. You can’t see it, smell it, or taste it.

The health risk is real and well-documented: the EPA estimates radon causes about 21,000 lung cancer deaths a year in the U.S. and calls it the number one cause of lung cancer among people who don’t smoke. The EPA’s action level is 4.0 pCi/L, with a recommendation to “consider fixing” between 2 and 4 pCi/L. There’s no perfectly safe level — but there is an easy way to know yours: test.

Does Naples really have radon? (Yes — test anyway)

Here’s where Florida buyers get a false sense of security. The EPA’s radon-zone map puts Collier County in Zone 3 — the lowest predicted-average category — and Florida has no Zone 1 (highest) counties at all. It’s tempting to conclude Naples homes are fine.

But the EPA is emphatic on this exact point: the zone map “is not intended to be used to determine if individual homes need to be tested… Homes with elevated levels of radon have been found in all three zones. All homes should be tested, regardless of zone designation.”

And Florida’s own data backs that up. The Florida Department of Health reports that about 1 in 5 Florida homes has radon above the action level, and that “elevated radon levels have been found in all types of Florida buildings, including manufactured homes, schools and high-rise condominiums.” In some areas, DOH says, one in two homes tests high. A slab foundation or a third-floor condo is not automatic protection — soil gas enters at the lowest ground contact, and pressure dynamics can move it upward through a building.

Florida’s radon disclosure law

Because radon is a known statewide issue, Florida law requires disclosure. Under Florida Statute 404.056(5), a radon notice must appear on a document executed at or before the contract for sale (and on most leases). The required language reads:

“RADON GAS: Radon is a naturally occurring radioactive gas that, when it has accumulated in a building in sufficient quantities, may present health risks to persons who are exposed to it over time. Levels of radon that exceed federal and state guidelines have been found in buildings in Florida. Additional information regarding radon and radon testing may be obtained from your county health department.”

This language is already built into standard Florida Realtors contracts, so you’ll see it — and agents have been fined for failing to provide it. It’s a disclosure, though, not a test: it tells you radon can be present, not whether this home has it.

How to test

DIY kits: inexpensive passive devices (charcoal canisters, alpha-track detectors). Short-term tests run 2 to 90 days; every test should run at least 48 hours. A long-term test (90+ days) better reflects your year-round average. Use a kit from a recognized program (NRPP/NRSB) and follow the instructions exactly.
In a real estate transaction: Florida requires that paid radon testing be done by a Florida-certified radon professional — not every home inspector is certified, so ask. Testing pairs naturally with your other inspections during the contract’s inspection period.
Free kits: the Florida Department of Health offers free radon test kits when in stock. As of 2026 the program was temporarily out of kits; the low-cost alternative the DOH and EPA point to is National Radon Program Services (sosradon.org).

If a home tests high: mitigation

A high result is not a deal-killer — it’s a fixable problem. The standard fix is active sub-slab depressurization (ASD): a contractor inserts a suction pipe through the slab and connects it to a continuously running vent fan that draws radon from beneath the home and discharges it above the roofline. It runs 24/7 and includes a warning gauge if it ever fails.

These systems typically reduce radon by 50% to 99%. The EPA deliberately doesn’t publish a fixed price (it varies by home), but Florida-certified mitigation contractors commonly quote roughly $800–$2,500, often around $1,200–$1,500. Only Florida-certified mitigators may do the work for a fee. Retest after installation, and about every two years thereafter. A documented mitigation system is a clean answer at resale, too.

How I help

On any Naples home — slab, single-family, or condo — I’ll make sure the radon disclosure is handled, help you fit a certified radon test into your inspection window if you want one, and treat a high reading as a routine negotiation item, not a crisis. Looking for a tester? See my recommended inspection pros.