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 Boundary County, Idaho
EPA puts Boundary County in Zone 1, its highest radon zone, and 20.0% of its 45 reported radon tests (2008 to 2017, laboratory totals) 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
20.0%
21.5 pts below ID
- Boundary
- 20.0%
- Idaho
- 41.5%
45 tests, 2008 to 2017
Median result
2.1pCi/L
Below action level
- Boundary
- 2.1 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
45
31st of 37 by tests
- Boundary
- 45
- Ada
- 3,030
Reported to CDC before any fix, 2008 to 2017
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Idaho
33 of 37
Lowest quarter
- Boundary
- 20.0%
- Bear Lake
- 78.1%
By share, of 37 with 30+ tests
Read a result for Boundary County
Starts at Boundary County's median, 2.1 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.1 pCi/L
Between 2 and 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Boundary County's median reported result, 2008 to 2017.
The data
Boundary County, At a glance
Boundary County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Boundary 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 Boundary County, 2008 to 2017, laboratory
Under 2 pCi/L: 47%2 to 4 pCi/L: 33%4 pCi/L and above: 20%
Of 45 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 21 | 46.7% |
| 2 to 4 pCi/L | 15 | 33.3% |
| 4 pCi/L and above | 9 | 20.0% |
What these figures count
These are the 45 tests reported to CDC for Boundary County over 2008 to 2017 (laboratory totals), 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: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).
Boundary County, Compared
Boundary County radon figures, compared
Calculated by Radon411Boundary County's 45 reported tests over the 2008 to 2017 laboratory totals had a middle value of 2.1 pCi/L and a maximum of 33.6 pCi/L, and 20.0% reached 4 pCi/L. Idaho as a whole (44 Idaho counties, pooled) comes to 41.5%: 21.5 points higher than here.
Among its state's counties it ranks 33rd of 37 Idaho counties with 30 or more tests for the same period. Statewide for the same period, Bear Lake County reported the highest share (78.1%) and Payette County the lowest (4.9%).
Below the action level, 21 tests (46.7%) came in under 2 pCi/L, against 31.5% statewide, and 15 tests (33.3%) fell between 2 and 4, against 26.9% statewide. CDC's ten-year totals for Boundary County went from 35 tests (2005 to 2014) to 45 (2008 to 2017), the share going from 20.0% to 20.0%.
EPA's 1993 zone map puts Boundary 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 33.0% in Bonner County to 63.2% in Pend Oreille County, WA.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Boundary County, Geology
The ground under Boundary County
PredictedUSGS's geologic map puts all of Boundary County's mapped land in one class: high radon potential. All of it lies in the area the map calls Northern Rocky Mountain Province, to which USGS gives a radon index of 12, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Northern Rocky Mountain Province | Diorite and granite of the Idaho batholith. | High | 12 | 99.8% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Boundary County beside the ground around it
Boundary County has more high-potential ground than Idaho as a whole: 100% of its land against 50.7%. Of the 3 counties that border it, none has as large a share of high-potential ground; Bonner County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Boundary County, Local resources
Radon testing and mitigation in Boundary County
- DHW Environmental Health ProgramDHW Environmental Health Program, run by Idaho Department of Health and Welfare, offers free or discounted test kits, and answers questions about testing and mitigation in Idaho.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
Order a free radon test kit.
- Compare kits
- See the Idaho directoryNo professionals are listed in Idaho yet. The state program can point you to registered testers and mitigators.
What Idaho's program says
- Phone
- 800-445-8647
- radon@dhw.idaho.gov
What it means
Boundary County, Questions
Questions about radon in Boundary County
Are radon levels high in Boundary County?
Over the 2008 to 2017 laboratory totals, 20.0% of the radon tests reported to CDC for Boundary County, Idaho were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.1 pCi/L. Of 37 Idaho counties with 30 or more tests for the same period, 32 reported a higher share; pooled, the state comes to 41.5%.
Which counties border Boundary County?
Boundary County borders 3 counties: Bonner County, ID, Pend Oreille County, WA and Lincoln County, MT.
Products
Boundary County, Products
Testing a home in Boundary County
In Boundary County, 20.0% of 45 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 41.5% pooled across Idaho. In Zone 1 the year-round level in Boundary 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
Boundary County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Boundary County
Explore
Boundary County, Bordering counties
Counties bordering Boundary County
Calculated by Radon411- Radon levels in Pend Oreille County, WAEPA zone 1
63.2%at or above 4 pCi/L
Median 4.8 pCi/L · 38 tests · 43.2 points above Boundary County
- Radon levels in Lincoln County, MTEPA zone 1
51.4%at or above 4 pCi/L
Median 4.0 pCi/L · 74 tests · 31.4 points above Boundary County
- Radon levels in Bonner County, IDEPA zone 1
33.0%at or above 4 pCi/L
Median 2.3 pCi/L · 321 tests · 13.0 points above Boundary County
Boundary County, Cities and towns
Cities and towns in Boundary County
Boundary County is growing: the Census Bureau puts it at 13,997 residents on July 1, 2025, up 15.3% from 12,141 in 2020. That works out to 11 people per square mile of land. No town dominates: Bonners Ferry, the largest, has 2,797 residents, 20.0% of the total. Together its 2 incorporated places hold 29.4% of those residents; the other 70.6% live outside any of them. Reported testing is thin here: 45 tests over 2008 to 2017, or 3.2 for every 1,000 residents (2025 estimate), where Idaho as a whole comes to 6.4.
From Bonners Ferry to Moyie Springs, CDC publishes no figure by town: each reads Boundary County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Bonners Ferry | 2,797 | +10.4% | 20.0% |
| Moyie Springs | 1,317 | +56.6% | 9.4% |
2 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).
Boundary County, Homes
Homes in Boundary County
Boundary County is a place of houses on their own lots: 82% of its 5,535 homes are detached single-family houses, against 74% across Idaho. Half of its homes were built before 1990, close to Idaho's 1990: 16% date from before 1960 and 33% from 2000 or later. Owners live in 78% of the occupied homes (Idaho: 72%), so for most households a test and a fix are their own to order.
| Homes | Boundary County | Idaho |
|---|---|---|
| Housing units | 5,535 | 776,683 |
| Detached houses | 82% | 74% |
| In buildings of 5 or more | 3% | 9% |
| Mobile homes | 12% | 7% |
| Built before 1960 | 16% | 18% |
| Built since 2000 | 33% | 35% |
| Middle year built | 1990 | 1990 |
| Owner-occupied | 78% | 72% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.