Cumberland County, NJ: EPA's radon zone, explained

EPA's own radon map rates Cumberland County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. Nationally, Cumberland County ranks higher in radon potential than 61% of rated counties (the 61st percentile).

Where Cumberland County sits nationally

Cumberland County, New Jersey is home to about 155,678 people across 483.38 square miles. That works out to roughly 322 people per square mile. By population, Cumberland County is the 149th largest of every county sharing its EPA zone — the 86th percentile by population within that zone. Cumberland County falls in EPA Radon Region 2, one of 83 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Cumberland County's Zone 2 prediction clears the 1.3 pCi/L national indoor average without reaching EPA's own 4 pCi/L point for recommending a fix. A county-wide moderate average, like Cumberland County's, can still hide a specific house well above or below it — testing is what actually answers the question.

If Cumberland County tests above the action level

For a Cumberland 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 New Jersey's state radon program

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

Where Cumberland County's figures come from

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