Radon does not have much of a reputation in Miami. Honestly, it barely has one at all. Most people file it under “things that happen in basements in places with actual winters,” not in a flat, limestone state where the water table is practically at ankle height.

That assumption made sense for a long time. It is worth updating now.

What Radon Actually Is

Radon is a naturally occurring radioactive gas, produced when uranium in soil and rock breaks down. It has no color, no smell, no taste, which is exactly why it is easy to ignore. It seeps into buildings through cracks in foundations, gaps around pipes, construction joints, basically any small opening between a structure and the ground, and it builds up in enclosed spaces, especially at lower levels.

The EPA considers long term radon exposure the second leading cause of lung cancer in the United States, after smoking, and estimates it contributes to roughly 21,000 lung cancer deaths a year nationally. This is not a fringe concern. It is a well documented one that simply has not made its way into the South Florida conversation yet.

Why Florida Is Not Quite as Low Risk as Everyone Assumes

Here is where the conventional wisdom starts to wobble. Florida does sit on limestone bedrock, which generally carries less uranium than the granite and shale that make states like Pennsylvania or Iowa higher risk by default. That part is true, and it matters.

But geology is not the whole story. Construction type matters just as much. Most South Florida homes are built on slabs, meaning a direct interface between the structure and the ground below. Any crack in that slab, any gap around a pipe, any expansion joint that was not sealed quite right becomes a potential entry point.

And here is the part that surprises most people: enclosed, air conditioned garages, which have become standard in newer construction, are actually one of the higher risk accumulation points for radon in Florida homes. An older garage with some airflow naturally diluted whatever radon found its way in. A sealed, climate controlled garage does not.

Florida’s Department of Health acknowledges radon as a statewide issue and recommends testing for all homes. Elevated readings have shown up across multiple counties, including parts of Miami-Dade that would not typically be flagged as high risk.

What This Means If You Are Renovating

This is where it becomes directly relevant to what we do, and why we are bringing it up at all.

A renovation that opens walls, touches the slab, adds a room over the garage, or creates new enclosed space can change a home’s radon profile. Even good upgrades, like better insulation and tighter windows, can increase radon levels by reducing the natural air leakage that used to dilute it.

If you are planning a renovation and have not tested for radon, do it before the design is locked in. It is inexpensive, completely non invasive, and gives you information that can genuinely shape design decisions. A basic test kit runs about fifteen to twenty dollars. Professional testing typically runs one hundred fifty to three hundred dollars. If mitigation turns out to be needed, a standard residential system generally runs eight hundred to twenty-five hundred dollars.

Compare that to retrofitting mitigation into a finished renovation, and the math on testing early is not complicated at all.

What Mitigation Actually Looks Like

In a Florida slab on grade home, radon mitigation typically means a sub slab depressurization system: a pipe through the slab connected to a small fan that pulls radon laden air from below the slab and vents it safely above the roofline. It is quiet, low maintenance, and very effective.

When it is planned for during a renovation, it integrates cleanly into the architecture, often nearly invisible. When it gets added after the fact, it tends to involve more visible pipe runs and more disruption to a home you just finished. Garage and lower level spaces may need a slightly different configuration, but the principle is the same: create a pressure difference that keeps radon moving away from the spaces you actually live in.

Our Take

We are not trying to alarm anyone. South Florida is not a radon hotspot, and most homes here test below the EPA’s action threshold of 4 picocuries per liter.

But “below the threshold” and “zero” are two different things, and the data is clear enough that this deserves a spot on the pre-renovation checklist, especially for homes with enclosed garages, finished lower level spaces, or a lot of slab.

We have started including a radon testing recommendation as part of our existing conditions assessments for renovation projects. Not because it is required, but because it is responsible, the information is genuinely useful, and the cost of getting it is about what you would spend on lunch.

If you have questions about radon and your specific property, or want to fold a radon assessment into a larger pre-renovation evaluation, we are happy to talk it through.

FAQs on The Radon Problem That Miami Is Facing