What EPA's radon map says about Seminole County

EPA places Seminole County in Zone 3 - Low Potential — a predicted county-wide average indoor radon level below 2 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Seminole County sits at the 31st percentile nationally for radon potential — above 31 of every 100 rated counties.

Where Seminole County sits nationally

About 494,605 people live in Seminole County, Florida, spread over 309.391 square miles. Population density there runs about 1,599 people per square mile. Among counties sharing Seminole County's EPA zone, it outranks 95% of them by population. EPA's geology-based Region 4 groups Seminole County with 735 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Seminole County's predicted average sits below the national indoor average of about 1.3 pCi/L, well under EPA's 4 pCi/L action level. A Zone 3 label describes Seminole County's average, not any one basement or slab in it — testing is still the only way an individual homeowner actually finds out.

Testing and mitigation in Seminole County

Mitigation cost doesn't depend on Seminole County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.

Find Florida's state radon program

Seminole County's test kit answers today; a Airthings radon monitor keeps answering for Seminole County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Code RADONZONE-10OFF takes 10% off at checkout.

More on how this number was built

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.