Radon is a colorless, odorless, and tasteless naturally occurring radioactive gas. It forms from the natural breakdown of uranium found in soil, rock, and water. Radon is present in Florida and can accumulate to dangerous concentrations inside homes, regardless of the warm climate or construction style. The only way for homeowners to determine if this invisible hazard exists is through specific testing.
Geological Origins and High-Risk Zones
The underlying geology of Florida is the primary reason radon gas is a concern throughout the state. Radon is a decay product of uranium, which is naturally present in the state’s phosphate rock deposits. Central Florida has a history of extensive phosphate mining, which can concentrate these uranium-containing materials.
When phosphate ore is processed or disturbed, the radium-226 remaining in the soil and phosphogypsum waste products continues its radioactive decay, releasing radon gas. The highly porous limestone bedrock and sandy, permeable soil allow the gas to move easily upward toward the surface. Elevated indoor levels have been found across all counties, with areas like Central Florida, including Polk and Hillsborough counties, noted for higher concentrations.
State and federal agencies have mapped radon potential zones, classifying areas based on the predicted potential for elevated indoor levels. While some counties are categorized as having lower potential, the varying geology and soil composition mean that one home can have safe levels while a neighbor’s may not. The potential for elevated indoor radon exists in every Florida county, making location-based assumptions unreliable. Building materials and how a house interacts with the soil beneath it play a more direct role than regional classification.
Health Implications of Radon Exposure
Radon is a health concern because its radioactive decay products are solid particles that attach to dust and are inhaled. Once inside the lungs, these particles emit high-energy alpha radiation that damages the cellular lining of the airways. This cellular damage can lead to genetic mutations and the development of malignant cells.
Long-term exposure significantly increases the risk of developing lung cancer. Radon is recognized as the leading cause of lung cancer among non-smokers and the second leading cause overall, after cigarette smoking. The Environmental Protection Agency estimates that radon exposure is responsible for thousands of lung cancer deaths annually in the United States. Because the gas is undetectable without specialized testing, it poses a risk to occupants over many years.
Home Testing Procedures and Interpretation
The only accurate way for a Florida homeowner to determine their risk is by conducting an indoor air test. Testing devices should be placed in the lowest occupied level of the home, such as the first floor of a slab-on-grade house. They must be kept away from drafts, excessive heat, and high humidity. Homeowners can use two primary types of tests.
Short-term tests are conducted over two to seven days and provide a quick snapshot of the radon concentration. They are often used for real estate transactions or as an initial screening tool. Long-term tests measure the concentration for 90 days or more, providing a more accurate average of the home’s annual radon level by accounting for daily and seasonal fluctuations.
Radon concentration is measured in picocuries per liter of air (pCi/L). The U.S. Environmental Protection Agency (EPA) recommends that homeowners take action if the result is 4.0 pCi/L or higher. Even below this threshold, the EPA suggests considering mitigation for levels between 2.0 and 4.0 pCi/L, as no level of radon exposure is considered risk-free. If a short-term test yields 4.0 pCi/L or more, a second test is recommended to confirm the reading before proceeding with mitigation.
Mitigation Strategies for Elevated Levels
If testing confirms an elevated radon level of 4.0 pCi/L or more, permanent mitigation is necessary to protect occupants. The most common and reliable solution is the installation of an active Sub-slab Depressurization (SSD) system. This system works by creating a negative pressure field beneath the concrete slab or foundation.
A vent pipe is inserted through the slab into the soil, and an inline fan is installed in the attic or outside the home. This continuously draws the radon gas from the ground. The gas is then safely vented into the outdoor air above the roofline, where it rapidly disperses. While sealing foundation cracks is necessary, it is rarely sufficient as a stand-alone mitigation technique.
Homeowners should hire a state-certified or licensed radon mitigation professional to design and install the system. These professionals ensure the system is correctly sized and installed according to specific building codes. A properly installed SSD system can successfully reduce indoor radon concentrations by 80% to 99%.