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New Hampshire Radon Map and Levels by County

New Hampshire's counties span EPA Zones 1 and 2. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

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  • Share at 4+ pCi/L

    31.8%

    4.2 pts below U.S.

    New Hampshire
    31.8%
    U.S.
    36.0%

    19,181 tests across 10 counties, 2005 to 2014

  • Rank among states

    21 of 47

    Middle of the states

    New Hampshire
    31.8%
    Nebraska
    60.4%

    By share, every state pooled the same way, 2005 to 2014

  • Counties in EPA Zone 1

    1 of 10

    Some at highest potential

    Zone 1
    1
    Zone 2
    9

    Most counties sit in Zone 2; Zone 1 is the highest potential

  • Highest county

    48.0%

    Carroll County

    Carroll
    48.0%
    Sullivan
    12.0%

    Counties with 30+ tests, 2005 to 2014

Read a result for New Hampshire

Starts at EPA's action level

4.0pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 4.0 pCi/L

At or above 4 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 4 and aboveEPA says fix it

This result is at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. 31.8% of New Hampshire's reported tests reached 4 pCi/L, 2005 to 2014.

Interpret this readingWhat a fix costs

The data

New Hampshire, At a glance

New Hampshire at a glance

Predicted: EPA radon zone

10 of 10 counties classified

EPA classifies counties, not states. Of the 10 counties in New Hampshire with a zone, 1 is in Zone 1 and 9 in Zone 2.

  • Zone 1: Highest predicted potentialgreater than 4 pCi/L1 of 10 counties · 10.0%
  • Zone 2: Moderate predicted potential2 to 4 pCi/L9 of 10 counties · 90.0%

An EPA radon zone predicts a whole county. It is not intended to determine whether any individual home should be tested: homes with elevated levels occur in all three zones, and EPA recommends testing every home regardless of zone.

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

CDC test figures, county by county

CDC publishes New Hampshire's radon test figures by county: 10 of its 10 counties have one. Each one's share is in the county list.

How to read these figures

New Hampshire, Compared

New Hampshire radon figures, compared

Calculated by Radon411
New Hampshire, 2005 to 2014, laboratory
31.8%
of 19,181 tests at or above 4 pCi/L, pooled
Against the U.S.
−4.2points
36.0% pooled
Rank among the states
21 of 47
1 is the highest share
Counties with 30 or more tests
10
Highest
48.0%
Carroll County
Lowest
12.0%
Sullivan County

New Hampshire pools to 31.8%: that share of 19,181 reported tests from 10 counties over the 2005 to 2014 laboratory totals reached EPA's action level. Nationally the pooled share is 36.0%: 4.2 points higher than here.

Among 47 states pooled the same way it ranks 21st, with Missouri (32.4%) above it and Virginia (30.3%) below. Carroll County reports the highest share (48.0% of 513 tests) and Sullivan County the lowest (12.0%); the most tests came from Hillsborough County, 6,479 of them at 31.7%.

Across its 4 overlapping ten-year totals, the share went from 31.8% (2005 to 2014) to 35.0% (2008 to 2017), up 3.3 points, with 2008 to 2017 the highest at 35.0%. By band, 5 counties at 30% to 50%, 3 counties at 15% to 30%, 2 counties at 5% to 15%.

EPA's 1993 map puts 1 of its 10 classified counties in Zone 1; against that, 31.8% of the tests reported since reached 4 pCi/L.

New Hampshire ranked among 47 states by pooled share of tests at or above 4 pCi/L, 2005 to 2014, laboratory
StateRankCountiesTestsAt or above 4 pCi/L
Indiana16 of 479233,02639.3%
West Virginia17 of 47558,95237.3%
Maine18 of 47168,95136.6%
Tennessee19 of 479523,04133.2%
Missouri20 of 4711542,53032.4%
New Hampshire21 of 471019,18131.8%
Virginia22 of 4713239,39130.3%
New Mexico23 of 47304,64329.7%
Washington24 of 47386,61727.2%
Oregon25 of 473417,18327.2%
Connecticut26 of 47823,28026.5%
New Hampshire's highest counties with 30 or more tests, by share at or above 4 pCi/L, 2005 to 2014, laboratory
CountyRankTestsAt or above 4 pCi/L
Carroll County1 of 1051348.0%
Strafford County2 of 101,09241.2%
Rockingham County3 of 105,34836.8%
Coos County4 of 1041736.2%
Hillsborough County5 of 106,47931.7%
Belknap County6 of 1058629.4%
Merrimack County7 of 101,61526.5%
Grafton County8 of 101,64926.0%
Cheshire County9 of 1087514.2%
Sullivan County10 of 1060712.0%
New Hampshire's counties with 30 or more tests, by their own share at or above 4 pCi/L, 2005 to 2014, laboratory
ShareCountiesTheir testsFor example
50% or more00None
30% to 50%513,849Carroll County, Strafford County, Rockingham County
15% to 30%33,850Belknap County, Merrimack County, Grafton County
5% to 15%21,482Cheshire County, Sullivan County
Under 5%00None
New Hampshire ten-year laboratory totals, pooled, against the United States
PeriodCountiesTestsAt or above 4 pCi/LUnited StatesChange from the row before
2008 to 20171015,60835.0%35.7%+1.0 points
2007 to 20161017,60734.0%35.8%+1.7 points
2006 to 20151018,75532.3%36.3%+0.6 points
2005 to 20141019,18131.8%36.0%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period. CDC publishes no state or national figure.

New Hampshire, Counties

New Hampshire counties by EPA zone

Predicted

All 10 counties, grouped by the zone EPA predicts and ordered by their reported share at or above 4 pCi/L, under New Hampshire's map. Each county has a page of its own.

New Hampshire radon map by county: EPA radon zones. Map of New Hampshire's 10 counties shaded by EPA radon zone: Zone 1 in red-orange, Zone 2 in amber. 1 in Zone 1, 9 in Zone 2, 0 in Zone 3.
New Hampshire radon map by countyEPA radon zones for New Hampshire's counties: 1 county in Zone 1, 9 counties in Zone 2, 0 counties in Zone 3.A prediction for each county, not a reading of any home; elevated homes occur in all three zones.

The 10 highest in New Hampshire, 2005 to 2014

Local help

New Hampshire, Local resources

Local resources in New Hampshire

Who to ask in New Hampshire: its radon program, test kits and professionals.

What New Hampshire's program says
Licensing of radon professionals
There is no requirement in New Hampshire for those professionals testing for radon to be certified but it is recommended to use a nationally certified radon measurement professional especially if a real estate transaction is involved.

What it means

New Hampshire, Questions

Questions about radon in New Hampshire

Is radon a problem in New Hampshire?

Of the 10 counties in New Hampshire that EPA's Map of Radon Zones classifies, 1 carry Zone 1 (the highest predicted potential), 9 Zone 2 and 0 Zone 3. Pooled from 10 counties, 31.8% of the 19,181 radon tests reported to CDC over the 2005 to 2014 laboratory totals were at or above 4 pCi/L, 21st of 47 states.

Which New Hampshire counties are in EPA radon Zone 1?

Zone 1 holds 1 county in New Hampshire: Carroll County.

Which New Hampshire counties have the highest radon?

Carroll County 48.0% (513 tests) leads New Hampshire by the share of reported tests at or above 4 pCi/L, 2005 to 2014, laboratory, then Strafford County 41.2% (1,092 tests), Rockingham County 36.8% (5,348 tests), Coos County 36.2% (417 tests), Hillsborough County 31.7% (6,479 tests).

Which EPA region is New Hampshire in?

New Hampshire is in EPA Region 1: New England.

Products

New Hampshire, Products

Testing a home in New Hampshire

31.8% of the 19,181 tests reported to CDC for New Hampshire over the 2005 to 2014 laboratory totals reached 4 pCi/L: a short-term kit (2 to 90 days) gives a first answer in days, a long-term test the year-round average. A short-term kit (2 to 90 days) is the quick first check for a home in New Hampshire; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for New Hampshire homes, compared

Explore

Cities in New Hampshire with their own page

Radon data is published by county, not by city. Each city page sets the figures of the counties the city lies in side by side.