Johnson County, GA: EPA's radon zone, explained

EPA's own radon map rates Johnson County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Nationally, Johnson County ranks higher in radon potential than 6% of rated counties (the 6th percentile).

Where Johnson County sits nationally

Johnson County, Georgia is home to about 9,178 people across 303.019 square miles. Averaged across its land area, Johnson County runs about 30 people per square mile. By population, Johnson County is the 844th largest of every county sharing its EPA zone — the 18th percentile by population within that zone. Geologically, Johnson County is grouped into EPA Region 4 alongside 735 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

At Zone 3, Johnson 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. A Zone 3 label describes Johnson County's average, not any one basement or slab in it — testing is still the only way an individual homeowner actually finds out.

If Johnson County tests above the action level

For a Johnson 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 Georgia's state radon program

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

Where Johnson County's figures come from

Johnson County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.