Short-term kit
PicoCan short-term charcoal canister radon test
- Lab fee included
Method: Charcoal
In home: 48 to 96 hours
Locations and reports
Radon Levels in Coos County, New Hampshire
EPA puts Coos County in Zone 2, its middle radon zone, and high results are common there: 52.3% of the 44 radon tests reported to CDC (2021) came back at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Share at 4+ pCi/L
52.3%
9.6 pts above NH
- Coos
- 52.3%
- NH
- 42.7%
44 tests, 2021
Median result
4.3pCi/L
Action level reached
- Coos
- 4.3 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2021
Tests reported
44
10th of 10 by tests
- Coos
- 44
- Rockingham
- 638
Reported to CDC before any fix, 2021
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Rank in NH
2 of 10
Top quarter
- Coos
- 52.3%
- Carroll
- 54.0%
By share, of 10 with 30+ tests
Read a result for Coos County
Starts at Coos County's median, 4.3 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.3 pCi/L
At or above 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 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. Coos County's median reported result, 2021.
The data
Coos County, At a glance
Coos County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Coos County is a
USGS geologic potential: Moderate across 84% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Coos County, 2021
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2018 | 59.6% |
| 2019 | 40.3% |
| 2020 | 52.3% |
| 2021 | 52.3% |
2021: 52.3%. Across these years the share ran from 40.3% to 59.6%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 44 tests reported to CDC for Coos County over 2021, many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.
Measured: CDC tracking data. Figure above: 2021. Measured data period: 2005 to 2021 (every CDC figure on file).
Coos County, Compared
Coos County radon figures, compared
Calculated by Radon411More than half: 52.3% of the 44 radon tests reported to CDC for Coos County in 2021 read at least 4 pCi/L. That places it 2nd of 10 New Hampshire counties with 30 or more tests for the same period. That is 9.6 points above the 42.7% pooled from 10 New Hampshire counties.
The median result, 4.3 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 86.9 pCi/L. The rest split 34.1% under 2 pCi/L and 13.6% from 2 to 4 (New Hampshire: 32.3% and 25.0%). The reported tests do not follow EPA's Zone 2 label for Coos County (predicted average between 2 and 4 pCi/L): 52.3% of them reached 4 pCi/L, fewer than that label suggests.
1 of its 2 bordering counties with figures ran higher, led by Carroll County at 54.0%; Grafton County reported 44.4%. Statewide for the same period, Carroll County reported the highest share (54.0%) and Cheshire County the lowest (19.4%).
The busiest year on file was 2019, with 62 tests reported; the quietest, 2021, had 44.
Over 4 years of annual figures the share fell 7.3 points, from 59.6% in 2018 to 52.3% in 2021; its peak was 59.6% in 2018. Nationally, every county with a figure for the same period pools to 24.4%; Coos County sits 27.9 points above it. CDC also counts 13 tests taken after mitigation in Coos County for the same period: tests in homes where a fix was already in.
Coos CountyNew Hampshire, pooled
52.3% % of tests42.7% % of tests
| Year | Tests | Coos County, at or above 4 pCi/L | New Hampshire, pooled |
|---|---|---|---|
| 2018 | 52 | 59.6% | 34.6% |
| 2019 | 62 | 40.3% | 40.6% |
| 2020 | 44 | 52.3% | 40.2% |
| 2021 | 44 | 52.3% | 42.7% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Coos County, Geology
The ground under Coos County
PredictedMost of the ground under Coos County is one class on USGS's geologic map: 83.7% of its land is moderate radon potential, with 16.3% high. The map puts 63.2% of Coos County in the area it calls White Mountains and 15.8% in White Mountains, with 5 smaller areas beside them. USGS gives both a radon index of 10, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| White Mountains | Cambrian-Devonian schist, slate, quartzite, metavolcanic rocks, granite. | Moderate | 10 | 63.2% |
| White Mountains | Middle to Late Ordovician intrusive rocks ranging from gabbro to syenite. | Moderate | 10 | 15.8% |
| White Mountains | Devonian-Carboniferous two-mica granite. | High | 13 | 7.7% |
| White Mountains | Jurassic-Cretaceous rocks of the White Mountain and New England-Quebec igneous succession. | High | 13 | 6.9% |
| Whitefield Lowlands | Middle to Late Ordovician intrusive rocks ranging from gabbro to syenite. | Moderate | 10 | 3.0% |
| Eastern New England Upland | Late Cambrian-Early Devonian limestone, conglomerate, phyllite, schist, slate. | Moderate | 10 | 1.0% |
One smaller area is not listed. Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Coos County beside the ground around it
On high-potential ground Coos County is close to New Hampshire as a whole: 16.3% of its land against 18.8%. Of the 4 counties that border it, 3 have more high-potential ground, Oxford County, ME the most at 85.1%.
The map rates the ground, not the air in any home.
Local help
Coos County, Local resources
Radon testing and mitigation in Coos County
- New Hampshire Radon ProgramNew Hampshire Radon Program, run by New Hampshire Department of Health and Human Services, does not license radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in New Hampshire.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
The NH Radon Program provides free radon test kits to NH residents.
- Compare kits
- See the New Hampshire directoryNo professionals are listed in New Hampshire yet. The state program can point you to registered testers and mitigators.
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
Coos County, Questions
Questions about radon in Coos County
Are radon levels high in Coos County?
In 2021, 52.3% of the radon tests reported to CDC for Coos County, New Hampshire were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.3 pCi/L. Of 10 New Hampshire counties with 30 or more tests for the same period, 1 reported a higher share; pooled, the state comes to 42.7%.
Which counties border Coos County?
Coos County borders 4 counties: Essex County, VT, Oxford County, ME, Grafton County, NH and Carroll County, NH.
Products
Coos County, Products
Testing a home in Coos County
In Coos County, 52.3% of 44 tests reported to CDC in 2021 reached 4 pCi/L, against 42.7% pooled across New Hampshire. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Coos County; a long-term test tells the year-round average.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL416 long-term radon test kit, lab fee included
- Lab fee included
Method: Alpha track
In home: 90 days to 12 months
MonitorAranet
Radon Plus battery digital radon monitor with an e-ink screen
- C-NRPP 2024/25: Approved
- Battery
- Bluetooth
- Alarm
- Screen, app
Method: Ion chamber
First reading: Within 10 minutes
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Coos County, Bordering counties
Counties bordering Coos County
Calculated by Radon411- Radon levels in Carroll County, NHEPA zone 1
54.0%at or above 4 pCi/L
Median 4.3 pCi/L · 161 tests · 1.7 points above Coos County
- Radon levels in Grafton County, NHEPA zone 2
44.4%at or above 4 pCi/L
Median 3.0 pCi/L · 142 tests · 7.9 points below Coos County
- Radon levels in Essex County, VTEPA zone 2
33.3%at or above 4 pCi/L
Median 2.5 pCi/L · 18 tests · 19.0 points below Coos County
- Radon levels in Oxford County, MEEPA zone 1
No CDC figure for 2021; its page reads it against its own neighbours.
Coos County, Cities and towns
Cities and towns in Coos County
Coos County's population has barely moved since 2020: 31,343 residents on July 1, 2025 against 31,235 then, by the Census Bureau's estimates. That works out to 17 people per square mile of land. Berlin, its one incorporated place, has 9,502 residents, 30.3% of the total. CDC's 44 reported tests for 2021 work out to 1.4 per 1,000 residents (2025 estimate), close to New Hampshire's 1.6.
Berlin is the one incorporated place here; CDC publishes no figure by town, so it reads Coos County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Berlin | 9,502 | +1.0% | 30.3% |
One incorporated place, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025).
Coos County, Homes
Homes in Coos County
Of Coos County's 20,589 homes, 68% are detached houses, against 63% across New Hampshire; 10% are mobile homes. The homes are older than New Hampshire's as a whole: half were built before 1969 (1978 for New Hampshire), and 44% date from before 1960. 74% of occupied homes are lived in by their owner (New Hampshire: 73%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Coos County | New Hampshire |
|---|---|---|
| Housing units | 20,589 | 644,253 |
| Detached houses | 68% | 63% |
| In buildings of 5 or more | 7% | 15% |
| Mobile homes | 10% | 5% |
| Built before 1960 | 44% | 29% |
| Built since 2000 | 14% | 18% |
| Middle year built | 1969 | 1978 |
| Owner-occupied | 74% | 73% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.