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 Lassen County, California
EPA puts Lassen County in Zone 3, its lowest radon zone, and only 4 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
22.2%
Washoe County
- Washoe
- 22.2%
1 of 5 neighbours have 30+ tests, 2008 to 2017
Nearest county
11.4%
Butte County, 88 miles
- Butte
- 11.4%
- California
- 10.3%
Share at 4+ pCi/L, 35 tests, 2008 to 2017
Ground above low
10.1%
32.5 pts below California
- Lassen
- 10.1%
- California
- 42.7%
Share of land USGS rates moderate or high potential
Tests reported
4
Too few for a share
- Lassen
- 4
- Needed
- 30
2008 to 2017, 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 Lassen 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
Lassen County, At a glance
Lassen County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
USGS geologic potential: Low across 90% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Lassen County, 2008 to 2017, laboratory
CDC holds 4 reported tests for Lassen County over the 2008 to 2017 laboratory totals, with a median of 1.1 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Lassen County beside the counties around it is how this page reads it.
What these figures count
Only 4 tests were reported to CDC for Lassen 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).
Lassen County, Compared
Lassen County radon figures, compared
Calculated by Radon411CDC's largest figure for Lassen County rests on 4 tests over the 2008 to 2017 laboratory totals, 0 of them at or above 4 pCi/L, so each test moves its share by 25.0 points and no rank or comparison is drawn from it. Results reached as high as 1.3 pCi/L, with a middle value of 1.1 pCi/L.
Washoe County, NV, the one bordering county with a figure over the 2008 to 2017 laboratory totals, reported 22.2% of its tests at or above 4 pCi/L. Farther out, Butte County (88 miles away) at 11.4%, Nevada County (95 miles away) at 25.0% and Placer County (111 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 Lassen County in Zone 3, its lowest label: a predicted county average under 2 pCi/L. USGS geology rates 90% of the county's land low radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Lassen County, Geology
The ground under Lassen County
PredictedMost of the ground under Lassen County is one class on USGS's geologic map: 89.9% of its land is low radon potential, with 10.1% moderate. The map puts 72.6% of Lassen County in the area it calls Modoc Plateau and 17.3% in Cascade Range, with 2 smaller areas beside them. USGS gives both a radon index of 8, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Modoc Plateau | Tertiary basalt flows, upper Tertiary to Quaternary basalt flows, and lesser amounts of andesite and rhyolite. | Low | 8 | 72.6% |
| Cascade Range | Upper Tertiary and Quaternary extrusive rocks, mainly basalt and lesser andesite and rhyolite. | Low | 8 | 17.3% |
| 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 | 6.7% |
| Northern Basin and Range | Precambrian metamorphic rocks, late Precambrian and Paleozoic metamorphosed and unmetamorphosed sedimentary rocks, Mesozoic and Tertiary intrusive rocks, and Tertiary sedimentary and volcanic rocks. | Moderate | 9 | 3.5% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Lassen County beside the ground around it
Across California 0.1% of the land is rated high; none of Lassen County's is. Of the 5 counties that border it, 4 have more moderate-potential ground, Sierra County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Lassen County, Local resources
Radon testing and mitigation in Lassen 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
Lassen County, Questions
Questions about radon in Lassen County
Are radon levels high in Lassen County?
Over the 2008 to 2017 laboratory totals, 0.0% of the radon tests reported to CDC for Lassen County, California were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.1 pCi/L. Washoe County, NV, the one bordering county with a figure over the 2008 to 2017 laboratory totals, reported 22.2% of its tests at or above 4 pCi/L.
Which counties border Lassen County?
Lassen County borders 5 counties: Plumas County, CA, Washoe County, NV, Sierra County, CA, Modoc County, CA and Shasta County, CA.
Products
Lassen County, Products
Testing a home in Lassen County
No CDC figure names Lassen County; the nearest county with one, Butte County (88 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 Lassen 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
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
Lassen County, Bordering counties
Counties bordering Lassen 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 Washoe County, NVEPA zone 2
22.2%at or above 4 pCi/L
Median 1.9 pCi/L · 5,046 tests
- Radon levels in Shasta County, CAEPA zone 3
21.7%at or above 4 pCi/L
Median 2.0 pCi/L · 23 tests
- Radon levels in Sierra County, CAEPA zone 2
0.0%at or above 4 pCi/L
Median 1.2 pCi/L · 1 test
- Radon levels in Modoc County, CAEPA zone 3
No CDC figure for 2008 to 2017; its page reads it against its own neighbours.
Lassen County, Cities and towns
Cities and towns in Lassen County
Lassen County has been losing residents: from 32,349 in 2020 to 28,117 on July 1, 2025, a fall of 13.1% by the Census Bureau's estimates. Spread over its land, that is 6.2 people to the square mile. Susanville, its one incorporated place, has 12,816 residents, 45.6% of the total. Reported testing is thin here: 4 tests over 2008 to 2017, or 0.1 for every 1,000 residents (2025 estimate), where California as a whole comes to 0.2.
Susanville is the one incorporated place here; CDC publishes no figure by town, so it reads Lassen County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Susanville | 12,816 | −22.1% | 45.6% |
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).
Lassen County, Homes
Homes in Lassen County
Of Lassen County's 12,232 homes, 74% are detached houses, against 57% across California; 13% are mobile homes. Half of its homes were built before 1977, close to California's 1976: 30% date from before 1960 and 17% 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 | Lassen County | California |
|---|---|---|
| Housing units | 12,232 | 14,532,683 |
| Detached houses | 74% | 57% |
| In buildings of 5 or more | 6% | 24% |
| Mobile homes | 13% | 4% |
| Built before 1960 | 30% | 27% |
| Built since 2000 | 17% | 18% |
| Middle year built | 1977 | 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.