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
Locations and reports
Radon Levels in Nevada County, California
EPA puts Nevada County in Zone 2, its middle radon zone, and 25.0% of its 260 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
25.0%
14.7 pts above CA
- Nevada
- 25.0%
- California
- 10.3%
260 tests, 2008 to 2017
Median result
2.0pCi/L
Below action level
- Nevada
- 2.0 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
260
12th of 33 by tests
- Nevada
- 260
- Los Angeles
- 2,363
Reported to CDC before any fix, 2008 to 2017
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 California
3 of 33
Top quarter
- Nevada
- 25.0%
- El Dorado
- 30.3%
By share, of 33 with 30+ tests
Read a result for Nevada County
Starts at Nevada County's median, 2.0 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.0 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. Nevada County's median reported result, 2008 to 2017.
The data
Nevada County, At a glance
Nevada County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Nevada 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 Nevada County, 2008 to 2017, laboratory
Under 2 pCi/L: 48%2 to 4 pCi/L: 27%4 pCi/L and above: 25%
Of 260 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 125 | 48.1% |
| 2 to 4 pCi/L | 70 | 26.9% |
| 4 pCi/L and above | 65 | 25.0% |
What these figures count
These are the 260 tests reported to CDC for Nevada 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).
Nevada County, Compared
Nevada County radon figures, compared
Calculated by Radon411Nevada County's 260 reported tests over the 2008 to 2017 laboratory totals had a middle value of 2.0 pCi/L and a maximum of 1100.0 pCi/L, and 25.0% reached 4 pCi/L. California as a whole (56 California counties, pooled) comes to 10.3%: 14.7 points lower than here.
Among its state's counties it ranks 3rd of 33 California counties with 30 or more tests for the same period. Statewide for the same period, El Dorado County reported the highest share (30.3%) and Sonoma County the lowest (0.8%).
Below the action level, 125 tests (48.1%) came in under 2 pCi/L, against 76.8% statewide, and 70 tests (26.9%) fell between 2 and 4, against 12.9% statewide. CDC's ten-year totals for Nevada County went from 239 tests (2005 to 2014) to 260 (2008 to 2017), the share going from 28.9% to 25.0%.
EPA's 1993 zone map puts Nevada County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 100% of the county's land moderate radon potential.
Next door, the shares run from 7.4% in Placer County to 22.2% in Washoe County, NV, with Washoe County, NV and Placer County below Nevada County.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Nevada County, Geology
The ground under Nevada County
PredictedUSGS's geologic map puts all of Nevada 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.
Nevada County beside the ground around it
Across California 0.1% of the land is rated high; none of Nevada County's is. Of the 4 counties that border it, none has as large a share of moderate-potential ground; Sierra County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Nevada County, Local resources
Radon testing and mitigation in Nevada 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
Nevada County, Questions
Questions about radon in Nevada County
Are radon levels high in Nevada County?
Over the 2008 to 2017 laboratory totals, 25.0% of the radon tests reported to CDC for Nevada County, California were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.0 pCi/L. Of 33 California counties with 30 or more tests for the same period, 2 reported a higher share; pooled, the state comes to 10.3%.
Which counties border Nevada County?
Nevada County borders 4 counties: Yuba County, CA, Placer County, CA, Sierra County, CA and Washoe County, NV.
Products
Nevada County, Products
Testing a home in Nevada County
In Nevada County, 25.0% of 260 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 10.3% pooled across California. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Nevada 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
Monitor
Hello Radon C battery radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- Battery
- Screen
Method: Alpha spectrometry
First reading: Within 24 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Nevada County, Bordering counties
Counties bordering Nevada County
Calculated by Radon411- Radon levels in Washoe County, NVEPA zone 2
22.2%at or above 4 pCi/L
Median 1.9 pCi/L · 5,046 tests · 2.8 points below Nevada County
- Radon levels in Placer County, CAEPA zone 2
7.4%at or above 4 pCi/L
Median 1.1 pCi/L · 283 tests · 17.6 points below Nevada County
- Radon levels in Yuba County, CAEPA zone 2
0.0%at or above 4 pCi/L
Median 0.1 pCi/L · 7 tests · 25.0 points below Nevada County
- Radon levels in Sierra County, CAEPA zone 2
0.0%at or above 4 pCi/L
Median 1.2 pCi/L · 1 test · 25.0 points below Nevada County
Nevada County, Cities and towns
Cities and towns in Nevada County
Nevada County's population has barely moved since 2020: 101,911 residents on July 1, 2025 against 102,280 then, by the Census Bureau's estimates. That works out to 106 people per square mile of land. No town dominates: Truckee, the largest, has 17,278 residents, 17.0% of the total. Together its 3 incorporated places hold 33.8% of those residents; the other 66.2% live outside any of them. Testing is reported here more often than across the state: CDC's 260 reported tests for 2008 to 2017 come to 2.6 for every 1,000 residents (2025 estimate), against 0.2 for California.
From Truckee to Nevada City, CDC publishes no figure by town: each reads Nevada County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Truckee | 17,278 | +3.0% | 17.0% |
| Grass Valley | 14,035 | −0.3% | 13.8% |
| Nevada City | 3,174 | +1.1% | 3.1% |
3 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).
Nevada County, Homes
Homes in Nevada County
Nevada County is a place of houses on their own lots: 83% of its 53,981 homes are detached single-family houses, against 57% across California. Half of its homes were built before 1983, close to California's 1976: 13% date from before 1960 and 19% from 2000 or later. 74% 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 | Nevada County | California |
|---|---|---|
| Housing units | 53,981 | 14,532,683 |
| Detached houses | 83% | 57% |
| In buildings of 5 or more | 6% | 24% |
| Mobile homes | 5% | 4% |
| Built before 1960 | 13% | 27% |
| Built since 2000 | 19% | 18% |
| Middle year built | 1983 | 1976 |
| Owner-occupied | 74% | 56% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.