Guilford County, NC radon potential

EPA's own radon map rates Guilford County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Nationally that's the 31st percentile for radon potential — Guilford County outranks 31% of every county EPA has rated.

Where Guilford County sits nationally

Guilford County, North Carolina is home to about 558,816 people across 645.993 square miles. Population density there runs about 865 people per square mile. Within its own EPA zone, Guilford County is bigger by population than 95% of the counties that share it. Geologically, Guilford County is grouped into EPA Region 4 alongside 735 other counties that share its rock and soil setting.

What this actually means for a house in Guilford County

Guilford 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. Even at Zone 3, Guilford County homes are not guaranteed a low reading — zone is a county-wide average, and EPA recommends testing every home regardless of zone.

Testing and mitigation in Guilford County

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 North Carolina's state radon program

For Guilford County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Guilford 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 Guilford County's figures come from

Guilford 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.