Locations and reports
Radon Levels in New Hampshire
What this means for you
- Your area: EPA rates 1 of New Hampshire's 10 classified counties Zone 1, the highest of its three radon zones. Zones are predictions for whole counties, and homes with elevated levels occur in all three zones.
- Local tests: CDC publishes New Hampshire's radon test results by county. Open your county below to see its figures.
- Your home: The only way to know your home’s level is to test it.
pCi/L (picocuries per liter) is the unit radon is measured in. EPA recommends fixing a home at 4 pCi/L or above, its action level.
For New Hampshire, EPA's Map of Radon Zones places 1 of its 10 classified counties in Zone 1, highest predicted potential, a prediction for each county as a whole. Radon levels vary from home to home, so only a test measures the level in yours.
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 describes predicted potential across a whole county. It is not intended to determine whether any individual home should be tested, and homes with elevated levels occur in all three zones. EPA recommends testing every home regardless of zone, and testing is the only way to know the radon level in a specific building.
This is a county-level geologic prediction. It is not a measurement of any address, and houses with elevated radon are found in all three zones.
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
CDC publishes New Hampshire's radon test figures by county: 10 of its 10 counties have one. Each county's share is in the county list.
New Hampshire, In figures
New Hampshire in figures
What the published data says about New Hampshire, in words. A zone and a share of tests describe an area, never the level in any one home.
Predicted
PredictedEPA places 1 of New Hampshire's 10 counties in Zone 1 and 9 in Zone 2.
The Zone 1 county: Carroll County.
Compared
Calculated by Radon41110% of New Hampshire's counties with a zone on file are in Zone 1, a smaller share than across all U.S. counties (34%). It is a share of counties, not of land, people or homes.
Reported tests
MeasuredCDC has no statewide testing figure for New Hampshire on file here.
10 of the 10 counties have a published county figure; the most tests in each one's latest year were reported for Rockingham County (593 in 2021), Hillsborough (533 in 2021) and Strafford County (231 in 2021).
Local record
New Hampshire's radon program is the New Hampshire Radon Program, run by New Hampshire Department of Health and Human Services; its contacts are under Local resources.
One city has a page setting the figures of the counties it lies in side by side: Manchester.
New Hampshire, Counties
New Hampshire counties by EPA zone
PredictedAll 10 counties, by the zone EPA predicts for each. Every county has its own report.
Zone 1: highest predicted potential1
Zone 2: moderate predicted potential9
- Belknap County36.3% of reported tests at or above 4 pCi/L, 2021
- Cheshire County19.4% of reported tests at or above 4 pCi/L, 2021
- Coos County52.3% of reported tests at or above 4 pCi/L, 2021
- Grafton County44.4% of reported tests at or above 4 pCi/L, 2021
- Hillsborough41.5% of reported tests at or above 4 pCi/L, 2021
- Merrimack County31.6% of reported tests at or above 4 pCi/L, 2021
- Rockingham County48.1% of reported tests at or above 4 pCi/L, 2021
- Strafford County47.9% of reported tests at or above 4 pCi/L, 2021
- Sullivan County23.3% of reported tests at or above 4 pCi/L, 2021
New Hampshire, Cities
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.
New Hampshire, Local resources
Local resources in New Hampshire
Who to ask in New Hampshire: the state's radon program, test kits and professionals.
New Hampshire Radon Program
New Hampshire Department of Health and Human Services
New Hampshire’s radon program answers questions about testing, mitigation and the rules where you live.
- 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.
Test kits
The program says: The NH Radon Program provides free radon test kits to NH residents.
Radon professionals
No professionals are listed in New Hampshire yet. The state program can point you to registered testers and mitigators.
See the New Hampshire directoryNew Hampshire, Questions
Questions about radon in New Hampshire
Common questions9 questions, answered from the figures above
Is radon a problem in New Hampshire?
EPA's Map of Radon Zones places 1 of the 10 New Hampshire counties it classifies in Zone 1, the highest predicted potential, 9 in Zone 2 and 0 in Zone 3. An EPA radon zone describes predicted potential across a whole county. It is not intended to determine whether any individual home should be tested, and homes with elevated levels occur in all three zones. EPA recommends testing every home regardless of zone, and testing is the only way to know the radon level in a specific building.
Who does radon mitigation in New Hampshire?
Radon411 has no certified mitigators listed for New Hampshire yet. EPA recommends having a qualified contractor fix a home with a radon problem, because lowering high radon levels takes technical knowledge and special skills, and some states require the work to be done by a licensed or certified professional.
How radon mitigation worksWhat mitigation costsRadon professionals in New Hampshire
How do I get a radon test in New Hampshire?
EPA says you can test your home yourself or hire a qualified radon test company, and that either approach takes only a small amount of time and effort. The New Hampshire radon program is the place to ask about certified testers and any test kit offer it runs.
How to test a homeFree and low-cost kits by stateNew Hampshire radon program
Which New Hampshire counties are in EPA radon Zone 1?
1 county is in Zone 1: Carroll County. Zone 1 is EPA's class for highest predicted potential, a predicted average indoor screening level greater than 4 pCi/L. A zone is a prediction for a county, not a measurement of any home.
Which New Hampshire counties have the highest radon?
10 of New Hampshire's 10 counties have an EPA radon zone published here. Radon411 will not rank counties on data it does not hold, and a zone is a prediction for an area rather than a measurement of any building.
What share of radon tests in New Hampshire are high?
CDC has published no statewide radon testing statistics for New Hampshire, so we cannot give a figure. Where CDC does publish one, the percentage describes radon tests reported to CDC, not homes.
Which EPA region is New Hampshire in?
New Hampshire is in EPA Region 1: New England.
Do I need to test my home in New Hampshire?
Yes, wherever you live in the state. Testing is the only way to know the radon level in a specific building. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. EPA recommends considering a fix when the level is between 2 and 4 pCi/L.
Why does this page show coverage rather than one radon level for New Hampshire?
A statewide figure averages counties with very different geology and very different numbers of reported tests, so it hides more than it shows. The county report is the level at which the EPA zone, the geologic potential and the reported testing statistics are actually published, which is why the county table above links to every one of them.
What these figures mean if you own, buy, sell or rent
The zone counts on this page describe counties across New Hampshire. They are predictions for areas, and none of them measures your building.
- How to test a home
If you own your home
Test the lowest lived-in level; a short-term kit screens in days, a long-term kit reflects the year.
- Buying a house: radon guide
If you are buying
Ask for past results and any system's post-mitigation test, and test during the sale.
- Selling a house: radon guide
If you are selling
Testing before you list puts the timing in your hands; disclosure rules differ by state.
- Radon in rental homes
If you rent, or rent out a home
A tenant can test; a fix is the owner's to make, and duties differ by state.
How long a test has to run, under what conditions, and what EPA says a result means: the testing standard, in full.
New Hampshire, Products
Testing and mitigation products
Whatever the figures for New Hampshire show, only a test tells you about one home.
Testing
- Short-term test kitsPassive detectors exposed for a few days under closed-building conditions, then analyzed by a lab.
- Long-term test kitsDetectors exposed for more than 90 days, for a closer picture of the annual average.
- Continuous monitorsPowered devices that log radon on a repeating cycle, often used for transaction tests.
- Digital detectorsConsumer devices that display a running radon reading without a lab.
- Water radon testsKits for radon dissolved in well water, analyzed by a lab.
Mitigation
- Mitigation fansThe inline fan that keeps a soil depressurization system running, sized by the installer.
- System indicatorsU-tube manometers and fan alarms that show whether a mitigation system is still working.
- Sealing materialsCrack, joint and sump sealing used alongside a mitigation system, not instead of one.
New Hampshire / Next steps
What to do next
Learn
Know what radon is
What radon is, how it gets indoors, and why a county zone is not a reading for your home.
Learn about radonTest
Test the building you live in
Short-term or long-term, where the device goes, and closed-house conditions.
How to testFix
Bring a high level down
How a mitigation system works, and the retest that confirms it.
How mitigation worksFind a pro
Hire a certified professional
Measurement and mitigation professionals by state, with their certifications.
Find a professional
Informational. Follow EPA guidance. EPA says all radon tests should be taken for a minimum of 48 hours, with windows and doors closed from 12 hours before a short-term test.