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 Calaveras County, California
EPA puts Calaveras County in Zone 2, its middle radon zone, and 17.6% of its 34 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
17.6%
7.3 pts above CA
- Calaveras
- 17.6%
- California
- 10.3%
34 tests, 2008 to 2017
Median result
1.7pCi/L
Below action level
- Calaveras
- 1.7 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
34
32nd of 33 by tests
- Calaveras
- 34
- 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
7 of 33
Top quarter
- Calaveras
- 17.6%
- El Dorado
- 30.3%
By share, of 33 with 30+ tests
Read a result for Calaveras County
Starts at Calaveras County's median, 1.7 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 1.7 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. Calaveras County's median reported result, 2008 to 2017.
The data
Calaveras County, At a glance
Calaveras County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Calaveras 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 Calaveras County, 2008 to 2017, laboratory
Under 2 pCi/L: 62%2 to 4 pCi/L: 21%4 pCi/L and above: 17%
Of 34 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 21 | 61.8% |
| 2 to 4 pCi/L | 7 | 20.6% |
| 4 pCi/L and above | 6 | 17.6% |
What these figures count
These are the 34 tests reported to CDC for Calaveras 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).
Calaveras County, Compared
Calaveras County radon figures, compared
Calculated by Radon411Calaveras County's 34 reported tests over the 2008 to 2017 laboratory totals had a middle value of 1.7 pCi/L and a maximum of 17.1 pCi/L, and 17.6% reached 4 pCi/L. California as a whole (56 California counties, pooled) comes to 10.3%: 7.3 points lower than here.
Among its state's counties it ranks 7th 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, 21 tests (61.8%) came in under 2 pCi/L, against 76.8% statewide, and 7 tests (20.6%) fell between 2 and 4, against 12.9% statewide. CDC's ten-year totals for Calaveras County went from 37 tests (2005 to 2014) to 34 (2008 to 2017), the share going from 10.8% to 17.6%.
EPA's 1993 zone map puts Calaveras 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 14.9% in San Joaquin County to 27.8% in Amador County, with San Joaquin County below Calaveras County.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Calaveras County, Geology
The ground under Calaveras County
PredictedUSGS's geologic map puts all of Calaveras 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.
Calaveras County beside the ground around it
Across California 0.1% of the land is rated high; none of Calaveras County's is. Of the 5 counties that border it, none has as large a share of moderate-potential ground; Alpine County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Calaveras County, Local resources
Radon testing and mitigation in Calaveras 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
Calaveras County, Questions
Questions about radon in Calaveras County
Are radon levels high in Calaveras County?
Over the 2008 to 2017 laboratory totals, 17.6% of the radon tests reported to CDC for Calaveras County, California were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.7 pCi/L. Of 33 California counties with 30 or more tests for the same period, 6 reported a higher share; pooled, the state comes to 10.3%.
Which counties border Calaveras County?
Calaveras County borders 5 counties: Amador County, San Joaquin County, Stanislaus County, Tuolumne County and Alpine County.
Products
Calaveras County, Products
Testing a home in Calaveras County
In Calaveras County, 17.6% of 34 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 Calaveras 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
MonitorINKBIRD
INK-RD3 battery radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- Battery
- Screen
First reading: Within 24 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Calaveras County, Bordering counties
Counties bordering Calaveras County
Calculated by Radon411- Radon levels in Alpine CountyEPA zone 2
63.2%at or above 4 pCi/L
Median 4.5 pCi/L · 19 tests · 45.6 points above Calaveras County
- Radon levels in Amador CountyEPA zone 2
27.8%at or above 4 pCi/L
Median 2.3 pCi/L · 36 tests · 10.2 points above Calaveras County
- Radon levels in Tuolumne CountyEPA zone 2
23.0%at or above 4 pCi/L
Median 1.4 pCi/L · 74 tests · 5.4 points above Calaveras County
- Radon levels in San Joaquin CountyEPA zone 3
14.9%at or above 4 pCi/L
Median 1.4 pCi/L · 74 tests · 2.7 points below Calaveras County
- Radon levels in Stanislaus CountyEPA zone 3
11.1%at or above 4 pCi/L
Median 1.4 pCi/L · 27 tests · 6.5 points below Calaveras County
Calaveras County, Cities and towns
Cities and towns in Calaveras County
The Census Bureau estimates 46,605 residents in Calaveras County for July 1, 2025, 1,256 more than in 2020 (+2.8%). That works out to 46 people per square mile of land. Angels, its one incorporated place, has 3,735 residents, 8.0% of the total. Testing is reported here more often than across the state: CDC's 34 reported tests for 2008 to 2017 come to 0.7 for every 1,000 residents (2025 estimate), against 0.2 for California.
Angels is the one incorporated place here; CDC publishes no figure by town, so it reads Calaveras County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Angels | 3,735 | +1.8% | 8.0% |
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).
Calaveras County, Homes
Homes in Calaveras County
Calaveras County is a place of houses on their own lots: 87% of its 27,579 homes are detached single-family houses, against 57% across California. Much of Calaveras County is recent building: 24% of its homes have gone up since 2000 and the middle year built is 1987, against 1976 for California. Owners live in 84% of the occupied homes (California: 56%), so for most households a test and a fix are their own to order.
| Homes | Calaveras County | California |
|---|---|---|
| Housing units | 27,579 | 14,532,683 |
| Detached houses | 87% | 57% |
| In buildings of 5 or more | 2% | 24% |
| Mobile homes | 7% | 4% |
| Built before 1960 | 10% | 27% |
| Built since 2000 | 24% | 18% |
| Middle year built | 1987 | 1976 |
| Owner-occupied | 84% | 56% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.