Is radon high in Sullivan County, New Hampshire?

Low. The model predicts a long-term basement average of 1.6 pCi/L in Sullivan County (close to the US average of 1.8 and about 25% below the New Hampshire average of 2.1). That is below the EPA's 2 pCi/L "consider fixing" threshold, though individual homes still vary. Ranked 10 of 10 New Hampshire counties.

Should I test for radon in Sullivan County?

Yes, once. The EPA recommends testing every home regardless of area, and the model's ZIP-level predictions in Sullivan County already range from 0.5 to 2.0 pCi/L. A short-term kit costs little and settles the question for your house.

What does EPA Radon Zone 2 mean for Sullivan County?

Zone 2 - moderate potential (2-4 pCi/L). The zone map dates from 1993 and classifies whole counties. The newer model's predicted average of 1.6 pCi/L does not line up with Zone 2, which is common - the EPA itself says high-radon homes exist in every zone. Neither replaces a test of your own home.

How much does radon mitigation cost in Sullivan County?

A standard active sub-slab depressurization system typically runs $800-$2,500 installed nationally; New Hampshire quotes vary with foundation type (slab, crawlspace, basement), home size and local labor. Get two or three bids from certified mitigators listed by your state radon program or the EPA's find-a-professional page.

Radon levels in Sullivan County, New Hampshire

LowEPA Zone 2

Predicted long-term basement average of 1.6 pCi/L (model estimate) across 13 ZIP codes - close to the US average of 1.8, about 25% below the New Hampshire average of 2.1. Ranked #10 of 10 New Hampshire counties.

Test Sullivan County, NH once anyway - radon varies house to house

The predicted basement average here is 1.6 pCi/L, below the EPA's 2 pCi/L "consider fixing" threshold. That's good news for the area - but the EPA still recommends every home be tested, because foundation cracks, soil pockets and ventilation make one house very different from its neighbor. One inexpensive kit settles it.

Get a short-term test kit →Or track it with a continuous monitor

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Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. How the numbers work.

1.6 ± 0.06

pCi/L predicted basement mean (model SD)

1.0 ± 0.07

pCi/L predicted upstairs (above-ground) mean

0.5-2.0

range of ZIP-level basement predictions in the county

What this means for Sullivan

The typical Sullivan County home is predicted below 2 pCi/L, the lowest band. That is the best case an area can show - but it describes the average house, and the ZIP-level predictions within the county still span 0.5 to 2.0 pCi/L.

Note that the EPA classifies Sullivan County as Zone 2 while the newer model predicts 1.6 pCi/L. The zone map predates two decades of test data; where they disagree, we grade on the model but show both. County figures weight each ZIP by its 2010 Census population, so they describe where people live rather than empty land.

Comparable New Hampshire counties: Belknap County (1.8), Cheshire County (1.8), Grafton County (1.9), Merrimack County (2.1). The state's highest is Carroll County at 2.3 pCi/L.

ZIP codes in Sullivan County

Predicted basement and upstairs means by ZIP (model estimate). ZIPs whose land is mostly in this county.

ZIP	Basement	Upstairs	Grade
03743	1.3 ± 0.05	0.8	Low
03773	1.7 ± 0.05	1.1	Low
03603	1.8 ± 0.05	1.1	Low
03753	1.7 ± 0.09	1.2	Low
03782	1.9 ± 0.06	1.1	Low
03781	1.9 ± 0.05	0.9	Low
03745	2.0 ± 0.06	1.2	Low
03605	1.7 ± 0.06	1.3	Low
03280	0.5 ± 0.13	0.8	Low
03284	1.5 ± 0.06	1.2	Low
03752	1.7 ± 0.07	1.2	Low
03770	1.8 ± 0.06	1.0	Low
03607	1.7 ± 0.07	1.1	Low

If your test comes back at 4 pCi/L or higher

Mitigation is a routine job: a fan-driven pipe that vents soil gas from under the slab to above the roofline, typically $800-$2,500 installed (typical range; local quotes vary). Use certified professionals: EPA find-a-professional. Read the full mitigation guide.

Sullivan County radon questions

Is radon high in Sullivan County, New Hampshire?: Low. The model predicts a long-term basement average of 1.6 pCi/L in Sullivan County (close to the US average of 1.8 and about 25% below the New Hampshire average of 2.1). That is below the EPA's 2 pCi/L "consider fixing" threshold, though individual homes still vary. Ranked 10 of 10 New Hampshire counties.
Should I test for radon in Sullivan County?: Yes, once. The EPA recommends testing every home regardless of area, and the model's ZIP-level predictions in Sullivan County already range from 0.5 to 2.0 pCi/L. A short-term kit costs little and settles the question for your house.
What does EPA Radon Zone 2 mean for Sullivan County?: Zone 2 - moderate potential (2-4 pCi/L). The zone map dates from 1993 and classifies whole counties. The newer model's predicted average of 1.6 pCi/L does not line up with Zone 2, which is common - the EPA itself says high-radon homes exist in every zone. Neither replaces a test of your own home.
How much does radon mitigation cost in Sullivan County?: A standard active sub-slab depressurization system typically runs $800-$2,500 installed nationally; New Hampshire quotes vary with foundation type (slab, crawlspace, basement), home size and local labor. Get two or three bids from certified mitigators listed by your state radon program or the EPA's find-a-professional page.

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