Short-term kit
PicoCan short-term charcoal canister radon test
- Lab fee included
Method: Charcoal
In home: 48 to 96 hours
Locations and reports
Radon Levels in Trinity County, California
EPA puts Trinity County in Zone 3, its lowest radon zone. Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Nearest county
11.4%
Butte County, 105 miles
- Butte
- 11.4%
- California
- 10.3%
Share at 4+ pCi/L, 35 tests, 2008 to 2017
Ground above low
None
42.7 pts below California
- Trinity
- 0.0%
- California
- 42.7%
Share of land USGS rates moderate or high potential
Tests reported
0
None published
A home here needs its own test
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 Trinity 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
Trinity County, At a glance
Trinity 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
No CDC test figures here
CDC has published no radon test figures for Trinity County. Butte County, 105 miles away, is the nearest county with a figure over the 2008 to 2017 laboratory totals.
Trinity County, Compared
Trinity County radon figures, compared
Calculated by Radon411No CDC figure names Trinity County, in any year or ten-year total; over the 2008 to 2017 laboratory totals, the agency's counts reach 56 California counties without it. Pooled across 56 California counties, 10.3% of reported tests reached that level; across every county in the country with a figure, 35.7%.
The nearest counties with a figure are Butte County (105 miles away) at 11.4%, Sonoma County (147 miles away) at 0.8% and Yolo County (150 miles away) at 2.1%. 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 Trinity 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.
Trinity County, Geology
The ground under Trinity County
PredictedUSGS's geologic map puts all of Trinity County's mapped land in one class: low radon potential. The map puts 78.3% of Trinity County in the area it calls Klamath Mountains and 21.7% in Northern Coast Ranges. USGS gives both a radon index of 6, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Klamath Mountains | Metasedimentary and ultramafic metavolcanic rocks, and basalt. | Low | 6 | 78.3% |
| Northern Coast Ranges | Metamorphosed marine sedimentary rocks and ultramafic rocks. | Low | 6 | 21.7% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Trinity County beside the ground around it
Across California 0.1% of the land is rated high; none of Trinity County's is. Of the 5 counties that border it, 2 have more moderate-potential ground, Siskiyou County the most at 5.6%.
The map rates the ground, not the air in any home.
Local help
Trinity County, Local resources
Radon testing and mitigation in Trinity 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
Trinity County, Questions
Questions about radon in Trinity County
Are radon levels high in Trinity County?
No CDC testing statistics are published here for Trinity County, California yet. Of the 8 nearest counties with a figure, within 179 miles, the share of tests at or above 4 pCi/L runs from 0.8% to 25.0%.
Which counties border Trinity County?
Trinity County borders 5 counties: Humboldt County, Shasta County, Tehama County, Siskiyou County and Mendocino County.
Products
Trinity County, Products
Testing a home in Trinity County
No CDC figure names Trinity County; the nearest county with one, Butte County (105 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 Trinity County.
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
MonitorAranet
Radon Plus battery digital radon monitor with an e-ink screen
- C-NRPP 2024/25: Approved
- Battery
- Bluetooth
- Alarm
- Screen, app
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
Trinity County, Bordering counties
Counties bordering Trinity County
Calculated by Radon411- Radon levels in Siskiyou CountyEPA zone 3
25.0%at or above 4 pCi/L
Median 1.1 pCi/L · 8 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 Humboldt CountyEPA zone 3
20.0%at or above 4 pCi/L
Median 1.3 pCi/L · 20 tests
- Radon levels in Tehama CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 2.2 pCi/L · 6 tests
- Radon levels in Mendocino CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.7 pCi/L · 11 tests
Trinity County, Residents
Who lives in Trinity County
About 15,720 people live in Trinity County by the Census Bureau's estimate for July 1, 2025, 379 fewer than in 2020 (−2.4%). Spread over its land, that is 4.9 people to the square mile. CDC publishes no radon test count for Trinity County; across California its counts for 2008 to 2017 come to 0.2 tests for every 1,000 residents (2025 estimate).
Census lists no incorporated place in Trinity County: every home in it reads the county's figures.
Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025).
Trinity County, Homes
Homes in Trinity County
Trinity County is a place of houses on their own lots: 78% of its 8,122 homes are detached single-family houses, against 57% across California. Half of its homes were built before 1977, close to California's 1976: 25% date from before 1960 and 17% from 2000 or later. 73% 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 | Trinity County | California |
|---|---|---|
| Housing units | 8,122 | 14,532,683 |
| Detached houses | 78% | 57% |
| In buildings of 5 or more | 1% | 24% |
| Mobile homes | 18% | 4% |
| Built before 1960 | 25% | 27% |
| Built since 2000 | 17% | 18% |
| Middle year built | 1977 | 1976 |
| Owner-occupied | 73% | 56% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.