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 San Benito County, California
EPA puts San Benito County in Zone 2, its middle radon zone, and only 19 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
21.9%
Santa Cruz County
- Santa Cruz
- 21.9%
- Santa Clara
- 9.2%
4 of 5 neighbours have 30+ tests, 2008 to 2017
Nearest county
14.9%
Monterey County, 28 miles
- Monterey
- 14.9%
- California
- 10.3%
Share at 4+ pCi/L, 87 tests, 2008 to 2017
Ground above low
100.0%
57.3 pts above California
- San Benito
- 100.0%
- California
- 42.7%
Share of land USGS rates moderate or high potential
Tests reported
19
Too few for a share
- San Benito
- 19
- Needed
- 30
2008 to 2017, laboratory
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Read a result for San Benito 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
San Benito County, At a glance
San Benito County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
San Benito 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 San Benito County, 2008 to 2017, laboratory
CDC holds 19 reported tests for San Benito County over the 2008 to 2017 laboratory totals, with a median of 0.7 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). San Benito County beside the counties around it is how this page reads it.
What these figures count
Only 19 tests were reported to CDC for San Benito 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).
San Benito County, Compared
San Benito County radon figures, compared
Calculated by Radon411CDC's largest figure for San Benito County rests on 19 tests over the 2008 to 2017 laboratory totals, 0 of them at or above 4 pCi/L, so each test moves its share by 5.3 points and no rank or comparison is drawn from it. Results reached as high as 3.0 pCi/L, with a middle value of 0.7 pCi/L.
Of the counties bordering it, 4 have a figure over the 2008 to 2017 laboratory totals: Santa Cruz County reported the largest share at or above 4 pCi/L, 21.9%, and Santa Clara County the smallest, 9.2%, with Monterey County at 14.9% and Fresno County at 11.0% between. Farther out, Madera County (84 miles away) at 14.7%, Alameda County (85 miles away) at 6.7% and San Mateo County (89 miles away) at 9.2% 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 San Benito County in Zone 2, its middle label: a predicted county average between 2 and 4 pCi/L. USGS geology rates 100% of the county's land moderate radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
San Benito County, Geology
The ground under San Benito County
PredictedUSGS's geologic map puts all of San Benito County's mapped land in one class: moderate radon potential. All of it lies in the area the map calls Southern Coast Ranges, 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 |
|---|---|---|---|---|
| Southern Coast Ranges | Metamorphosed marine sedimentary rocks, ultramafic rocks, Triasic metamorphic rocks, Mesozoic granitic rocks, and a series of fault-bounded linear basins in which Teriary marine and continental sedimentary rocks were deposited. | 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.
San Benito County beside the ground around it
Across California 0.1% of the land is rated high; none of San Benito County's is. Of the 5 counties that border it, none has as large a share of moderate-potential ground; Monterey County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
San Benito County, Local resources
Radon testing and mitigation in San Benito 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
San Benito County, Questions
Questions about radon in San Benito County
Are radon levels high in San Benito County?
Over the 2008 to 2017 laboratory totals, 0.0% of the radon tests reported to CDC for San Benito County, California were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.7 pCi/L. Of the counties bordering it, 4 have a figure over the 2008 to 2017 laboratory totals: Santa Cruz County reported the largest share at or above 4 pCi/L, 21.9%, and Santa Clara County the smallest, 9.2%, with Monterey County at 14.9% and Fresno County at 11.0% between.
Which counties border San Benito County?
San Benito County borders 5 counties: Monterey County, Merced County, Santa Clara County, Santa Cruz County and Fresno County.
Products
San Benito County, Products
Testing a home in San Benito County
No CDC figure names San Benito County; the nearest county with one, Monterey County (28 miles away), reported 14.9% 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. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in San Benito 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
San Benito County, Bordering counties
Counties bordering San Benito County
Calculated by Radon411- Radon levels in Santa Cruz CountyEPA zone 2
21.9%at or above 4 pCi/L
Median 1.2 pCi/L · 105 tests
- Radon levels in Monterey CountyEPA zone 2
14.9%at or above 4 pCi/L
Median 0.8 pCi/L · 87 tests
- Radon levels in Fresno CountyEPA zone 2
11.0%at or above 4 pCi/L
Median 1.5 pCi/L · 100 tests
- Radon levels in Santa Clara CountyEPA zone 2
9.2%at or above 4 pCi/L
Median 0.9 pCi/L · 793 tests
- Radon levels in Merced CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 2.1 pCi/L · 5 tests
San Benito County, Cities and towns
Cities and towns in San Benito County
San Benito County is growing: the Census Bureau puts it at 70,082 residents on July 1, 2025, up 8.6% from 64,525 in 2020. That works out to 50 people per square mile of land. Hollister alone is home to 45,695 of them, 65.2% of the total. Together its 2 incorporated places hold 68.2% of those residents; the other 31.8% live outside any of them. CDC's 19 reported tests for 2008 to 2017 work out to 0.3 per 1,000 residents (2025 estimate), close to California's 0.2.
From Hollister to San Juan Bautista, CDC publishes no figure by town: each reads San Benito County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Hollister | 45,695 | +9.2% | 65.2% |
| San Juan Bautista | 2,122 | +1.4% | 3.0% |
2 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).
San Benito County, Homes
Homes in San Benito County
San Benito County is a place of houses on their own lots: 81% of its 20,937 homes are detached single-family houses, against 57% across California. Much of San Benito County is recent building: 25% of its homes have gone up since 2000 and the middle year built is 1988, against 1976 for California. 67% 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 | San Benito County | California |
|---|---|---|
| Housing units | 20,937 | 14,532,683 |
| Detached houses | 81% | 57% |
| In buildings of 5 or more | 5% | 24% |
| Mobile homes | 4% | 4% |
| Built before 1960 | 17% | 27% |
| Built since 2000 | 25% | 18% |
| Middle year built | 1988 | 1976 |
| Owner-occupied | 67% | 56% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.