Belknap County, NH radon potential

EPA places Belknap County in Zone 2 - Moderate Potential — a predicted county-wide average indoor radon level between 2 and 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Belknap County sits at the 57th percentile nationally for radon potential — above 57 of every 100 rated counties.

How Belknap County compares

Belknap County, New Hampshire is home to about 65,257 people across 401.912 square miles. Averaged across its land area, Belknap County runs about 162 people per square mile. Within its own EPA zone, Belknap County is bigger by population than 72% of the counties that share it. Belknap County falls in EPA Radon Region 1, one of 59 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Neither at the 4 pCi/L action level nor down at the roughly 1.3 pCi/L national indoor norm, Belknap County's Zone 2 prediction lands in the gap between the two. Nothing about a Zone 2 label lowers the case for testing in Belknap County — EPA recommends it in every zone, moderate included.

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

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. Whatever zone Belknap County carries, the zone explainer covers what it does and doesn't tell you about any one house.