Radon is a colorless, odorless radioactive gas produced by uranium naturally present in soil and rock. It is the second-leading cause of lung cancer in the United States, responsible for an estimated 21,000 deaths every year according to the EPA. In Florida, the combination of shallow limestone bedrock and airtight, continuously conditioned construction means indoor radon accumulates faster than most homeowners realize.
If you've just received a radon test result, this guide will help you interpret the number on your report and decide what to do next.
Radon levels explained: what your pCi/L number means
Radon is measured in picocuries per liter of air (pCi/L). The higher the number, the more radon is present. Here is how the EPA categorizes the ranges:
- Below 2.0 pCi/L — Low. Roughly the level of outdoor air. No action required, but the EPA notes any long-term exposure carries some risk. Retest every two years.
- 2.0 – 3.9 pCi/L — Consider mitigation. Below the EPA action level, but the WHO recommends mitigation above 2.7 pCi/L. Consider mitigation if the household includes children, smokers, or occupants who spend significant time in the lowest lived-in level.
- 4.0 – 9.9 pCi/L — Action recommended. The EPA action level. Mitigation is strongly recommended, and most systems reduce readings to below 2.0 pCi/L.
- 10.0 – 19.9 pCi/L — Prompt action. Mitigate within a few months. Long-term exposure at this level carries a lung-cancer risk comparable to smoking a pack of cigarettes per day.
- 20.0+ pCi/L — Urgent. Mitigate immediately. Consider limiting time in the lowest lived-in level until a system is installed.
How radon exposure compares to smoking
The easiest way to understand radon risk is to compare it to something familiar. According to EPA modeling, lifetime exposure at these levels carries roughly the same lung-cancer risk as smoking:
- 4 pCi/L — ~half a pack per day
- 8 pCi/L — ~a full pack per day
- 20 pCi/L — ~two packs per day
Radon risk is dose × time, so short-term visits to a high-radon environment are far less concerning than long-term residence. That's why the 48-hour test protocol we use is designed to estimate the level a family would encounter over months and years of normal occupancy.
Why Florida homes trend higher than you'd expect
Florida was long thought to be a low-radon state because most homes are single-story with no basement. That's a myth. Palm Beach, Broward, and Miami-Dade counties all sit on shallow limestone bedrock — the Anastasia, Fort Thompson, and Miami Formations — which allow soil gas to migrate freely upward through slab joints, plumbing chases, and expansion cracks. Combined with tight hurricane-rated envelopes and continuous air-conditioning, indoor radon accumulates in a way it simply doesn't in leaky, mixed-climate housing.
The Florida Department of Health has documented elevated readings in every county in the state. In Palm Beach and Broward, we've measured actionable radon in single-family homes, condos, luxury estates, and new construction alike.
Short-term vs long-term radon testing
Radon levels swing hour-to-hour and season-to-season based on weather, HVAC cycling, and how often doors and windows open. Because of that, a single reading is a snapshot — not a verdict.
- 48-hour short-term test. The EPA closed-building protocol we use for real estate transactions and initial screening. Accurate to within about 20% of the long-term average when performed correctly.
- 90-day long-term test. A more precise measurement of the annual average, recommended if your short-term result is between 2.0 and 4.0 pCi/L and you want more confidence before deciding whether to mitigate.
- Continuous radon monitor. Hour-by-hour logging. Most useful for diagnosing intermittent spikes or verifying a newly installed mitigation system.
What to do based on your result
- Below 2.0 pCi/L — retest in two years, and after any major renovation or HVAC change.
- 2.0 – 3.9 pCi/L — run a 90-day long-term test to confirm the annual average, then decide. If children or smokers live in the home, mitigate.
- 4.0+ pCi/L — install a mitigation system. A properly designed sub-slab depressurization system typically reduces readings to below 2.0 pCi/L within 24 hours.
- Any level, post-install — verify with an independent 48-hour post-mitigation test. We include this with every install we perform.
Frequently asked questions about radon levels
Is 2.0 pCi/L a safe radon level?
The EPA considers any radon exposure a health risk, but recommends mitigation at 4.0 pCi/L or above. Between 2.0 and 4.0 pCi/L, mitigation is considered optional but recommended — especially for households with children, smokers, or occupants who spend long hours on the lowest lived-in level.
How dangerous is 4.0 pCi/L of radon?
Long-term exposure at 4.0 pCi/L carries roughly the lung-cancer risk of smoking half a pack of cigarettes per day. It is the EPA's action level — meaning mitigation is recommended without delay.
Do I need to retest after mitigation?
Yes. Every professionally installed mitigation system should be verified with an independent 48-hour post-mitigation test to confirm the level is below 4.0 pCi/L. We include this test with every install.
How often should I test my Florida home?
The EPA recommends testing every two years and after any major renovation, HVAC replacement, or foundation repair. Florida's tight, air-conditioned construction can allow radon to accumulate faster than in colder-climate homes.
Get expert help interpreting your result
If you've received a radon test result and aren't sure what to do next, call (561) 261-2250 or send us your report for a free interpretation. We'll walk you through what the number means for your specific home and, if mitigation is warranted, quote a fixed price with financing available.