Nassau County, FL radon potential

EPA's own radon map rates Nassau County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Nassau County sits at the 26th percentile nationally for radon potential — above 26 of every 100 rated counties.

Nassau County by the numbers

Nassau County, Florida is home to about 104,376 people across 648.681 square miles. Averaged across its land area, Nassau County runs about 161 people per square mile. Within its own EPA zone, Nassau County is bigger by population than 80% of the counties that share it. Nassau County falls in EPA Radon Region 4, one of 736 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

At Zone 3, Nassau County's predicted county average is under the national indoor average (~1.3 pCi/L) and well below EPA's 4 pCi/L action level — outdoor air nationally runs about 0.4 pCi/L for comparison. Even at Zone 3, Nassau County homes are not guaranteed a low reading — zone is a county-wide average, and EPA recommends testing every home regardless of zone.

If Nassau County tests above the action level

A short-term test kit is the standard first step and typically costs far less than mitigation itself. If a test comes back at or above 4 pCi/L, a radon mitigation system for a typical home runs roughly $800–$2,500 (around $1,200 for a common single-family install), driven mainly by foundation type, not by county.

Find Florida's state radon program

For Nassau County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Nassau County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

Where Nassau County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Nassau County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.