Grafton County, NH radon potential

Grafton County is mapped as Zone 2 - Moderate Potential by EPA — meaning the county-wide average indoor level is predicted between 2 and 4 pCi/L. That puts Grafton County in the 59th percentile nationally for radon potential — higher than 59% of the counties EPA has rated.

How Grafton County compares

Grafton County, New Hampshire is home to about 93,045 people across 1,708.61 square miles. That works out to roughly 54 people per square mile. Within its own EPA zone, Grafton County is bigger by population than 79% of the counties that share it. Grafton County falls in EPA Radon Region 1, one of 59 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

Grafton 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 Grafton County's, can still hide a specific house well above or below it — testing is what actually answers the question.

If Grafton 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 New Hampshire's state radon program

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

Grafton County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. Whatever zone Grafton County carries, the zone explainer covers what it does and doesn't tell you about any one house.