Short-term kit
RA100 short-term liquid scintillation radon test kit
- Lab fee extra
Method: Liquid scintillation
In home: 48 to 96 hours
Locations and reports
Radon Levels in Sierra County, California
EPA puts Sierra County in Zone 2, its middle radon zone, and only 1 radon test from it is 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
25.0%
Nevada County
- Nevada
- 25.0%
- Washoe
- 22.2%
2 of 5 neighbours have 30+ tests, 2008 to 2017
Nearest county
25.0%
Nevada County, 24 miles
- Nevada
- 25.0%
- California
- 10.3%
Share at 4+ pCi/L, 260 tests, 2008 to 2017
Ground above low
100.0%
57.3 pts above California
- Sierra
- 100.0%
- California
- 42.7%
Share of land USGS rates moderate or high potential
Tests reported
1
Too few for a share
- Sierra
- 1
- Needed
- 30
2008 to 2017, 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 Sierra 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
Sierra County, At a glance
Sierra County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Sierra County is a
USGS geologic potential: Moderate across 100% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Sierra County, 2008 to 2017, laboratory
CDC holds 1 reported test for Sierra County over the 2008 to 2017 laboratory totals, a result of 1.2 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Sierra County beside the counties around it is how this page reads it.
What these figures count
Only 1 test was reported to CDC for Sierra 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).
Sierra County, Compared
Sierra County radon figures, compared
Calculated by Radon411CDC's largest figure for Sierra County rests on 1 test over the 2008 to 2017 laboratory totals, 0 of them at or above 4 pCi/L, so each test moves its share by 100.0 points and no rank or comparison is drawn from it. Results reached as high as 1.2 pCi/L, with a middle value of 1.2 pCi/L.
Of the counties bordering it, 2 have a figure over the 2008 to 2017 laboratory totals: Nevada County reported the largest share at or above 4 pCi/L, 25.0%, and Washoe County, NV the smallest, 22.2%. Farther out, Placer County (37 miles away) at 7.4%, El Dorado County (55 miles away) at 30.3% and Butte County (58 miles away) at 11.4% 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 Sierra County in Zone 2, its middle label: a predicted county average between 2 and 4 pCi/L. USGS geology rates 100% of the county's land moderate radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Sierra County, State data
California's own radon test data
MeasuredWhat California's own agencies publish about radon tests in Sierra County, with their period. These are not CDC's figures and are never added to them.
MeasuredState figures, not CDC's
What the Nevada Radon Education Program reports for the ZIP codes in Sierra County
The Nevada Radon Education Program publishes its figures by ZIP code, not by county. These are the ZIP code that lie wholly or partly in Sierra County, each with the state's own figures for it. Period: 1989-2015.
| ZIP code | What the state reports |
|---|---|
| 89439 | average 10.2 pCi/L |
- NBMG says the results are based on independently tested homes, not scientific sampling.
- The service publishes an average for each ZIP code but no count of tests.
- Site specific testing is the only way to determine local radon concentrations.
- A ZIP code that crosses the county line is listed whole; its figures cover all of it.
Measured: Nevada Radon Education Program data, 1989-2015.
Sierra County, Geology
The ground under Sierra County
PredictedUSGS's geologic map puts all of Sierra County's mapped land in one class: moderate radon potential. All of it lies in the area the map calls Sierra Nevada, to which USGS gives a radon index of 9, in the moderate band (9 to 11).
| 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 | 100% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Sierra County beside the ground around it
Across California 0.1% of the land is rated high; none of Sierra County's is. Of the 5 counties that border it, none has as large a share of moderate-potential ground; Nevada County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Sierra County, Local resources
Radon testing and mitigation in Sierra 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
Sierra County, Questions
Questions about radon in Sierra County
Are radon levels high in Sierra County?
Over the 2008 to 2017 laboratory totals, 0.0% of the radon tests reported to CDC for Sierra County, California were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.2 pCi/L. Of the counties bordering it, 2 have a figure over the 2008 to 2017 laboratory totals: Nevada County reported the largest share at or above 4 pCi/L, 25.0%, and Washoe County, NV the smallest, 22.2%.
Which counties border Sierra County?
Sierra County borders 5 counties: Plumas County, CA, Nevada County, CA, Yuba County, CA, Lassen County, CA and Washoe County, NV.
Products
Sierra County, Products
Testing a home in Sierra County
No CDC figure names Sierra County; the nearest county with one, Nevada County (24 miles away), reported 25.0% 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 Sierra 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
MonitorForensics Detectors
FD-65-RADON rechargeable radon detector with a color screen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
First reading: Within 6 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Sierra County, Bordering counties
Counties bordering Sierra County
Calculated by Radon411- Radon levels in Plumas County, CAEPA zone 2
38.1%at or above 4 pCi/L
Median 2.1 pCi/L · 21 tests
- Radon levels in Nevada County, CAEPA zone 2
25.0%at or above 4 pCi/L
Median 2.0 pCi/L · 260 tests
- Radon levels in Washoe County, NVEPA zone 2
22.2%at or above 4 pCi/L
Median 1.9 pCi/L · 5,046 tests
- Radon levels in Yuba County, CAEPA zone 2
0.0%at or above 4 pCi/L
Median 0.1 pCi/L · 7 tests
- Radon levels in Lassen County, CAEPA zone 3
0.0%at or above 4 pCi/L
Median 1.1 pCi/L · 4 tests
Sierra County, Cities and towns
Cities and towns in Sierra County
About 3,098 people live in Sierra County by the Census Bureau's estimate for July 1, 2025, 128 fewer than in 2020 (−4.0%). Spread over its land, that is 3.3 people to the square mile. Loyalton, its one incorporated place, has 709 residents, 22.9% of the total. CDC's 1 reported test for 2008 to 2017 work out to 0.3 per 1,000 residents (2025 estimate), close to California's 0.2.
Loyalton is the one incorporated place here; CDC publishes no figure by town, so it reads Sierra County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Loyalton | 709 | −4.3% | 22.9% |
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).
Sierra County, Homes
Homes in Sierra County
Sierra County is a place of houses on their own lots: 92% of its 2,099 homes are detached single-family houses, against 57% across California. Half of its homes were built before 1974, close to California's 1976: 30% date from before 1960 and 16% from 2000 or later. Owners live in 78% of the occupied homes (California: 56%), so for most households a test and a fix are their own to order.
| Homes | Sierra County | California |
|---|---|---|
| Housing units | 2,099 | 14,532,683 |
| Detached houses | 92% | 57% |
| In buildings of 5 or more | 3% | 24% |
| Mobile homes | 4% | 4% |
| Built before 1960 | 30% | 27% |
| Built since 2000 | 16% | 18% |
| Middle year built | 1974 | 1976 |
| Owner-occupied | 78% | 56% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.