Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
Locations and reports
Radon Levels in Hunterdon County, New Jersey
EPA puts Hunterdon County in Zone 1, its highest radon zone, and 21.1% of its 3,748 reported radon tests (2022) were 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
21.1%
11.4 pts above NJ
- Hunterdon
- 21.1%
- New Jersey
- 9.7%
3,748 tests, 2022
Median result
1.4pCi/L
Below action level
- Hunterdon
- 1.4 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2022
Tests reported
3,748
13th of 21 by tests
- Hunterdon
- 3,748
- Bergen
- 11,440
Reported to CDC before any fix, 2022
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in New Jersey
3 of 21
Top quarter
- Hunterdon
- 21.1%
- Warren
- 24.6%
By share, of 21 with 30+ tests
Read a result for Hunterdon County
Starts at Hunterdon County's median, 1.4 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 1.4 pCi/L
Below 2 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is below 2 pCi/L, the level at which EPA says a fix should be considered. Hunterdon County's median reported result, 2022.
The data
Hunterdon County, At a glance
Hunterdon County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Hunterdon County in
USGS geologic potential: High across 100% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Hunterdon County, 2022
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 25.4% |
| 2015 | 28.8% |
| 2016 | 28.6% |
| 2017 | 26.6% |
| 2018 | 22.4% |
| 2019 | 25.2% |
| 2020 | 25.7% |
| 2021 | 22.0% |
| 2022 | 21.1% |
2022: 21.1%. Across these years the share ran from 21.1% to 28.8%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 3,748 tests reported to CDC for Hunterdon County over 2022, 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: 2022. Measured data period: 2014 to 2022 (every CDC figure on file).
Hunterdon County, Compared
Hunterdon County radon figures, compared
Calculated by Radon411Hunterdon County's 3,748 reported tests in 2022 had a middle value of 1.4 pCi/L and a maximum of 619.3 pCi/L, and 21.1% reached 4 pCi/L. New Jersey as a whole (21 New Jersey counties, pooled) comes to 9.7%: 11.4 points lower than here.
Among its state's counties it ranks 3rd of 21 New Jersey counties with 30 or more tests for the same period. Statewide for the same period, Warren County reported the highest share (24.6%) and Cape May County the lowest (0.0%).
Below the action level, 2,231 tests (59.5%) came in under 2 pCi/L, against 74.9% statewide, and 725 tests (19.3%) fell between 2 and 4, against 15.4% statewide. The busiest year on file was 2020, with 4,683 tests reported; the quietest, 2014, had 2,916.
EPA's 1993 zone map puts Hunterdon County in Zone 1, a predicted county average above 4 pCi/L. USGS geology rates 100% of the county's land high radon potential.
Next door, the shares run from 10.6% in Mercer County to 24.6% in Warren County, with Somerset County, Morris County and Mercer County below Hunterdon County. Over 9 years of annual figures the share fell 4.3 points, from 25.4% in 2014 to 21.1% in 2022; its peak was 28.8% in 2015.
Hunterdon CountyNew Jersey, pooled
21.1% % of tests9.7% % of tests
| Year | Tests | Hunterdon County, at or above 4 pCi/L | New Jersey, pooled |
|---|---|---|---|
| 2014 | 2,916 | 25.4% | 12.8% |
| 2015 | 3,175 | 28.8% | 12.5% |
| 2016 | 3,485 | 28.6% | 12.5% |
| 2017 | 3,972 | 26.6% | 11.9% |
| 2018 | 3,671 | 22.4% | 11.0% |
| 2019 | 4,035 | 25.2% | 11.2% |
| 2020 | 4,683 | 25.7% | 11.7% |
| 2021 | 4,383 | 22.0% | 10.3% |
| 2022 | 3,748 | 21.1% | 9.7% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Hunterdon County, Geology
The ground under Hunterdon County
PredictedUSGS's geologic map puts all of Hunterdon County's mapped land in one class: high radon potential. The map puts 77.9% of Hunterdon County in the area it calls Southern Piedmont and 21.8% in Highlands. USGS gives the first a radon index of 14 and the second 15, both in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Southern Piedmont | Black shale, sandstone and siltstone. | High | 14 | 77.9% |
| Highlands | Glacial deposits, granite, pegmatites, and gneiss. | High | 15 | 21.8% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Hunterdon County beside the ground around it
Hunterdon County has more high-potential ground than New Jersey as a whole: 100% of its land against 29.8%. Of the 5 counties that border it, none has as large a share of high-potential ground; Somerset County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Hunterdon County, Local resources
Radon testing and mitigation in Hunterdon County
- Radon SectionRadon Section, run by New Jersey Department of Environmental Protection, licenses or certifies radon professionals, offers free or discounted test kits and states the rule for disclosing radon when a home is sold, and answers questions about testing and mitigation in New Jersey.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
Check with your municipal or county health department for free radon test kits or purchase a test kit from a hardware store or a NJ certified radon business.
- Compare kits
- Professionals in New Jersey15 professionals are listed in New Jersey.
What New Jersey's program says
- Phone
- 800-648-0394
- Licensing of radon professionals
By law, all businesses and professionals conducting radon testing and mitigation in New Jersey must be certified by the DEP.
- Disclosure when a home is sold or rented
Under the law, the seller must provide the buyer, at the time the contract of sale is entered into, with a copy of the results of the radon test and evidence of any mitigation or treatment.
What it means
Hunterdon County, Questions
Questions about radon in Hunterdon County
Are radon levels high in Hunterdon County?
In 2022, 21.1% of the radon tests reported to CDC for Hunterdon County, New Jersey were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.4 pCi/L. Of 21 New Jersey counties with 30 or more tests for the same period, 2 reported a higher share; pooled, the state comes to 9.7%.
Which counties border Hunterdon County?
Hunterdon County borders 5 counties: Somerset County, NJ, Warren County, NJ, Bucks County, PA, Mercer County, NJ and Morris County, NJ.
Products
Hunterdon County, Products
Testing a home in Hunterdon County
In Hunterdon County, 21.1% of 3,748 tests reported to CDC in 2022 reached 4 pCi/L, against 9.7% pooled across New Jersey. In Zone 1 the year-round level in Hunterdon County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.
Test kits and monitors3
See every kit and monitor
MonitorINKBIRD
INK-RD3 battery radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- Battery
- Screen
First reading: Within 24 hours
Short-term kit
RA400 short-term liquid scintillation radon test kit, lab fee included
- Lab fee included
Method: Liquid scintillation
In home: 48 to 96 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Hunterdon County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Hunterdon County
Explore
Hunterdon County, Bordering counties
Counties bordering Hunterdon County
Calculated by Radon411- Radon levels in Warren County, NJEPA zone 1
24.6%at or above 4 pCi/L
Median 1.5 pCi/L · 2,819 tests · 3.5 points above Hunterdon County
- Radon levels in Somerset County, NJEPA zone 1
15.4%at or above 4 pCi/L
Median 1.2 pCi/L · 7,679 tests · 5.7 points below Hunterdon County
- Radon levels in Morris County, NJEPA zone 1
13.6%at or above 4 pCi/L
Median 1.1 pCi/L · 10,939 tests · 7.5 points below Hunterdon County
- Radon levels in Mercer County, NJEPA zone 1
10.6%at or above 4 pCi/L
Median 0.9 pCi/L · 6,370 tests · 10.5 points below Hunterdon County
- Radon levels in Bucks County, PAEPA zone 1
No CDC figure for 2022; its page reads it against its own neighbours.
Hunterdon County, Cities and towns
Cities and towns in Hunterdon County
The Census Bureau estimates 131,781 residents in Hunterdon County for July 1, 2025, 3,008 more than in 2020 (+2.3%). That works out to 308 people per square mile of land. No town dominates: Flemington, the largest, has 4,856 residents, 3.7% of the total. Together its 12 incorporated places hold 19.2% of those residents; the other 80.8% live outside any of them. Testing is reported here more often than across the state: CDC's 3,748 reported tests for 2022 come to 28.4 for every 1,000 residents (2025 estimate), against 11.4 for New Jersey.
From Flemington to Stockton, CDC publishes no figure by town: each reads Hunterdon County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Flemington | 4,856 | −0.3% | 3.7% |
| Lambertville | 4,198 | +1.7% | 3.2% |
| High Bridge | 3,603 | +2.1% | 2.7% |
| Clinton | 2,794 | +1.0% | 2.1% |
| Glen Gardner | 1,690 | +1.2% | 1.3% |
| Lebanon | 1,676 | +1.0% | 1.3% |
| Frenchtown | 1,500 | +9.4% | 1.1% |
| Hampton | 1,443 | +0.8% | 1.1% |
| Milford | 1,224 | −0.2% | 0.9% |
| Califon | 1,034 | +1.5% | 0.8% |
| Bloomsbury | 802 | +1.1% | 0.6% |
| Stockton | 497 | +0.4% | 0.4% |
12 incorporated places, 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).
Hunterdon County, Homes
Homes in Hunterdon County
Of Hunterdon County's 51,908 homes, 74% are detached houses, against 53% across New Jersey; 8% are in buildings of five or more homes. Much of Hunterdon County is recent building: 13% of its homes have gone up since 2000 and the middle year built is 1979, against 1969 for New Jersey. Owners live in 85% of the occupied homes (New Jersey: 64%), so for most households a test and a fix are their own to order.
| Homes | Hunterdon County | New Jersey |
|---|---|---|
| Housing units | 51,908 | 3,775,842 |
| Detached houses | 74% | 53% |
| In buildings of 5 or more | 8% | 22% |
| Mobile homes | under 1% | 1% |
| Built before 1960 | 29% | 38% |
| Built since 2000 | 13% | 15% |
| Middle year built | 1979 | 1969 |
| Owner-occupied | 85% | 64% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.