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 Tehama County, California
EPA puts Tehama County in Zone 3, its lowest radon zone, and only 6 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, 46 miles
- Butte
- 11.4%
- California
- 10.3%
Share at 4+ pCi/L, 35 tests, 2008 to 2017
Ground above low
0.2%
42.5 pts below California
- Tehama
- 0.2%
- California
- 42.7%
Share of land USGS rates moderate or high potential
Tests reported
10
Too few for a share
- Tehama
- 10
- Needed
- 30
2005 to 2014, laboratory
EPA radon zone
Zone 3
Lower potential
- 1
- 2
- Zone 3
1 highest, 3 lowest
EPA predicts under 2 pCi/L indoors
Read a result for Tehama 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
Tehama County, At a glance
Tehama County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
USGS geologic potential: Low across 100% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Tehama County, 2008 to 2017, laboratory
CDC holds 6 reported tests for Tehama County over the 2008 to 2017 laboratory totals, with a median of 2.2 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Tehama County beside the counties around it is how this page reads it.
What these figures count
Only 6 tests were reported to CDC for Tehama 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).
Tehama County, Compared
Tehama County radon figures, compared
Calculated by Radon411CDC's largest figure for Tehama County rests on 10 tests over the 2005 to 2014 laboratory totals, 0 of them at or above 4 pCi/L, so each test moves its share by 10.0 points and no rank or comparison is drawn from it. Results reached as high as 2.8 pCi/L, with a middle value of 1.5 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 (97 miles away) at 25.0%, Yolo County (101 miles away) at 2.1% and Placer County (109 miles away) at 7.4% 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 Tehama County in Zone 3, its lowest label: a predicted county average under 2 pCi/L. USGS geology rates 100% of the county's land low radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Tehama County, Geology
The ground under Tehama County
PredictedMost of the ground under Tehama County is one class on USGS's geologic map: 99.8% of its land is low radon potential, with 0.2% moderate. The map puts 38.5% of Tehama County in the area it calls Cascade Range and 25.7% in Northern Coast Ranges, with 2 smaller areas beside them. USGS gives the first a radon index of 8 and the second 6, both in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Cascade Range | Upper Tertiary and Quaternary extrusive rocks, mainly basalt and lesser andesite and rhyolite. | Low | 8 | 38.5% |
| Northern Coast Ranges | Metamorphosed marine sedimentary rocks and ultramafic rocks. | Low | 6 | 25.7% |
| Great Valley | Quaternary alluvial gravel, sand, silt, clay. | Low | 8 | 22.0% |
| Klamath Mountains | Metasedimentary and ultramafic metavolcanic rocks, and basalt. | Low | 6 | 13.7% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Tehama County beside the ground around it
Across California 0.1% of the land is rated high; none of Tehama County's is. Of the 6 counties that border it, 2 have more moderate-potential ground, Plumas County the most at 84.3%.
The map rates the ground, not the air in any home.
Local help
Tehama County, Local resources
Radon testing and mitigation in Tehama 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
Tehama County, Questions
Questions about radon in Tehama County
Are radon levels high in Tehama County?
Over the 2008 to 2017 laboratory totals, 0.0% of the radon tests reported to CDC for Tehama County, California were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.2 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 Tehama County?
Tehama County borders 6 counties: Glenn County, Shasta County, Butte County, Trinity County, Plumas County and Mendocino County.
Products
Tehama County, Products
Testing a home in Tehama County
No CDC figure names Tehama County; the nearest county with one, Butte County (46 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. Zone 3 is the lowest label, yet homes at or above 4 pCi/L occur in every zone: a short-term kit (2 to 90 days) is the quick first check in Tehama County.
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
Wave Plus battery radon and air quality monitor
- C-NRPP 2024/25: Not included
- Battery
- Bluetooth
- App only
Method: Alpha spectrometry
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Tehama County, Bordering counties
Counties bordering Tehama County
Calculated by Radon411- Radon levels in Plumas CountyEPA zone 2
38.1%at or above 4 pCi/L
Median 2.1 pCi/L · 21 tests
- 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 Glenn CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 2.8 pCi/L · 2 tests
- Radon levels in Mendocino CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.7 pCi/L · 11 tests
- Radon levels in Trinity CountyEPA zone 3
No CDC figure for 2008 to 2017; its page reads it against its own neighbours.
Tehama County, Cities and towns
Cities and towns in Tehama County
About 64,665 people live in Tehama County by the Census Bureau's estimate for July 1, 2025, 1,095 fewer than in 2020 (−1.7%). That works out to 22 people per square mile of land. Its largest town, Red Bluff, has 14,404 residents, 22.3% of the total. Together its 3 incorporated places hold 35.7% of those residents; the other 64.3% live outside any of them. Reported testing is thin here: 10 tests over 2005 to 2014, or 0.2 for every 1,000 residents (2025 estimate), where California as a whole comes to 0.3.
From Red Bluff to Tehama, CDC publishes no figure by town: each reads Tehama County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Red Bluff | 14,404 | −2.2% | 22.3% |
| Corning | 8,260 | +0.6% | 12.8% |
| Tehama | 441 | +2.1% | 0.7% |
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).
Tehama County, Homes
Homes in Tehama County
Of Tehama County's 27,456 homes, 70% are detached houses, against 57% across California; 17% are mobile homes. Half of its homes were built before 1981, close to California's 1976: 21% date from before 1960 and 18% from 2000 or later. 68% 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 | Tehama County | California |
|---|---|---|
| Housing units | 27,456 | 14,532,683 |
| Detached houses | 70% | 57% |
| In buildings of 5 or more | 6% | 24% |
| Mobile homes | 17% | 4% |
| Built before 1960 | 21% | 27% |
| Built since 2000 | 18% | 18% |
| Middle year built | 1981 | 1976 |
| Owner-occupied | 68% | 56% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.