Jefferson County, AL: EPA's radon zone, explained

EPA's own radon map rates Jefferson County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. Jefferson County sits at the 65th percentile nationally for radon potential — above 65 of every 100 rated counties.

How Jefferson County compares

Jefferson County, Alabama is home to about 664,744 people across 1,111.567 square miles. Averaged across its land area, Jefferson County runs about 598 people per square mile. By population, Jefferson County is the 37th largest of every county sharing its EPA zone — the 97th percentile by population within that zone. Jefferson County falls in EPA Radon Region 4, one of 736 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Call it a middle case: above the 1.3 pCi/L most US homes average, below the 4 pCi/L line EPA uses to recommend mitigation — that's Jefferson County's Zone 2 prediction. A Zone 2 rating is a moderate county-wide average, not a guarantee about any one house in Jefferson County — testing is the only way to know an individual home's actual level.

Next steps for a home in Jefferson County

For a Jefferson County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find Alabama's state radon program

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

Where Jefferson County's figures come from

Jefferson County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.