Short-term kit
Radon Short Term Test Kit short-term charcoal radon test kit, lab fee included
- Lab fee included
Method: Charcoal
In home: 2 to 7 days
Locations and reports
Radon Levels in Plumas County, California
EPA puts Plumas County in Zone 2, its middle radon zone, and only 21 radon tests from it are on file with CDC (2008 to 2017, laboratory totals). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Highest bordering
11.4%
Butte County
- Butte
- 11.4%
1 of 6 neighbours have 30+ tests, 2008 to 2017
Nearest county
11.4%
Butte County, 47 miles
- Butte
- 11.4%
- California
- 10.3%
Share at 4+ pCi/L, 35 tests, 2008 to 2017
Ground above low
84.3%
41.6 pts above California
- Plumas
- 84.3%
- California
- 42.7%
Share of land USGS rates moderate or high potential
Tests reported
25
Too few for a share
- Plumas
- 25
- Needed
- 30
2007 to 2016, laboratory
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Read a result for Plumas County
Starts at EPA's action level
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
- 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.
The data
Plumas County, At a glance
Plumas County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Plumas 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 Plumas County, 2008 to 2017, laboratory
CDC holds 21 reported tests for Plumas County over the 2008 to 2017 laboratory totals, with a median of 2.1 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Plumas County beside the counties around it is how this page reads it.
What these figures count
Only 21 tests were reported to CDC for Plumas County over 2008 to 2017 (laboratory totals), and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.
Measured: CDC tracking data. Figure above: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).
Plumas County, Compared
Plumas County radon figures, compared
Calculated by Radon411CDC's largest figure for Plumas County rests on 25 tests over the 2007 to 2016 laboratory totals, 9 of them at or above 4 pCi/L, so each test moves its share by 4.0 points and no rank or comparison is drawn from it. Results reached as high as 18.2 pCi/L, with a middle value of 2.1 pCi/L.
Butte County, the one bordering county with a figure over the 2008 to 2017 laboratory totals, reported 11.4% of its tests at or above 4 pCi/L. Farther out, Nevada County (49 miles away) at 25.0%, Placer County (65 miles away) at 7.4% and El Dorado County (86 miles away) at 30.3% have figures too. Pooled across 56 California counties, 10.3% of reported tests reached that level; across every county in the country with a figure, 35.7%.
Statewide for the same period, El Dorado County reported the highest share (30.3%) and Sonoma County the lowest (0.8%). EPA's 1993 map puts Plumas County in Zone 2, its middle label: a predicted county average between 2 and 4 pCi/L. USGS geology rates 84% of the county's land moderate radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Plumas County, Geology
The ground under Plumas County
PredictedMost of the ground under Plumas County is one class on USGS's geologic map: 84.3% of its land is moderate radon potential, with 15.7% low. The map puts 84.3% of Plumas County in the area it calls Sierra Nevada and 15.7% in Cascade Range. USGS gives the first a radon index of 9, in the moderate band (9 to 11), and the second 8, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Sierra Nevada | Northern Sierra Nevada is underlain primarily by Paleozoic and Mesozoic metamorphic rocks. Granitic rocks predominate in the southern Sierrra Nevada , with lesser Mesozoic metamorphic rocks. | Moderate | 9 | 84.3% |
| Cascade Range | Upper Tertiary and Quaternary extrusive rocks, mainly basalt and lesser andesite and rhyolite. | Low | 8 | 15.7% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Plumas County beside the ground around it
Across California 0.1% of the land is rated high; none of Plumas County's is. Of the 6 counties that border it, 1 has more moderate-potential ground, Sierra County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Plumas County, Local resources
Radon testing and mitigation in Plumas County
- California Indoor Radon ProgramCalifornia Indoor Radon Program, run by California Department of Public Health, licenses or certifies radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in California.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
Discounted test kits can be purchased through our partner laboratory, Alpha Energy, for $14.95.
- Compare kits
- Professionals in California4 professionals are listed in California.
What California's program says
- Phone
- 1-800-745-7236
- Radonprogram@cdph.ca.gov
- Licensing of radon professionals
The Radon Program certifies all radon service providers operating in California.
What it means
Plumas County, Questions
Questions about radon in Plumas County
Are radon levels high in Plumas County?
Over the 2008 to 2017 laboratory totals, 38.1% of the radon tests reported to CDC for Plumas County, California were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.1 pCi/L. Butte County, the one bordering county with a figure over the 2008 to 2017 laboratory totals, reported 11.4% of its tests at or above 4 pCi/L.
Which counties border Plumas County?
Plumas County borders 6 counties: Lassen County, Sierra County, Butte County, Yuba County, Tehama County and Shasta County.
Products
Plumas County, Products
Testing a home in Plumas County
No CDC figure names Plumas County; the nearest county with one, Butte County (47 miles away), reported 11.4% of its tests at or above 4 pCi/L over the 2008 to 2017 laboratory totals, the only reading nearby until a test of this home. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Plumas County; a long-term test tells the year-round average.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
Monitor
EcoBlu plug-in digital radon monitor with a display
- C-NRPP 2024/25: Not included
- Plug-in
- Alarm
- Screen
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
Plumas County, Bordering counties
Counties bordering Plumas County
Calculated by Radon411- Radon levels in Shasta CountyEPA zone 3
21.7%at or above 4 pCi/L
Median 2.0 pCi/L · 23 tests
- Radon levels in Butte CountyEPA zone 3
11.4%at or above 4 pCi/L
Median 0.8 pCi/L · 35 tests
- Radon levels in Lassen CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 1.1 pCi/L · 4 tests
- Radon levels in Sierra CountyEPA zone 2
0.0%at or above 4 pCi/L
Median 1.2 pCi/L · 1 test
- Radon levels in Yuba CountyEPA zone 2
0.0%at or above 4 pCi/L
Median 0.1 pCi/L · 7 tests
- Radon levels in Tehama CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 2.2 pCi/L · 6 tests
Plumas County, Cities and towns
Cities and towns in Plumas County
Plumas County has been losing residents: from 19,745 in 2020 to 18,583 on July 1, 2025, a fall of 5.9% by the Census Bureau's estimates. Spread over its land, that is 7.3 people to the square mile. Portola, its one incorporated place, has 2,024 residents, 10.9% of the total. Testing is reported here more often than across the state: CDC's 25 reported tests for 2007 to 2016 come to 1.3 for every 1,000 residents (2025 estimate), against 0.3 for California.
Portola is the one incorporated place here; CDC publishes no figure by town, so it reads Plumas County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Portola | 2,024 | −2.9% | 10.9% |
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).
Plumas County, Homes
Homes in Plumas County
Plumas County is a place of houses on their own lots: 82% of its 15,037 homes are detached single-family houses, against 57% across California. Half of its homes were built before 1980, close to California's 1976: 18% date from before 1960 and 15% from 2000 or later. 75% of occupied homes are lived in by their owner (California: 56%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Plumas County | California |
|---|---|---|
| Housing units | 15,037 | 14,532,683 |
| Detached houses | 82% | 57% |
| In buildings of 5 or more | 3% | 24% |
| Mobile homes | 10% | 4% |
| Built before 1960 | 18% | 27% |
| Built since 2000 | 15% | 18% |
| Middle year built | 1980 | 1976 |
| Owner-occupied | 75% | 56% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.