Short-term kitKidde
442020 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 3 days
Locations and reports
Radon Levels in Santa Cruz County, California
EPA puts Santa Cruz County in Zone 2, its middle radon zone, and 21.9% of its 105 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
21.9%
11.6 pts above CA
- Santa Cruz
- 21.9%
- California
- 10.3%
105 tests, 2008 to 2017
Median result
1.2pCi/L
Below action level
- Santa Cruz
- 1.2 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
105
19th of 33 by tests
- Santa Cruz
- 105
- 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
6 of 33
Top quarter
- Santa Cruz
- 21.9%
- El Dorado
- 30.3%
By share, of 33 with 30+ tests
Read a result for Santa Cruz County
Starts at Santa Cruz County's median, 1.2 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 1.2 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. Santa Cruz County's median reported result, 2008 to 2017.
The data
Santa Cruz County, At a glance
Santa Cruz County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Santa Cruz 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 Santa Cruz County, 2008 to 2017, laboratory
Under 2 pCi/L: 60%2 to 4 pCi/L: 18%4 pCi/L and above: 22%
Of 105 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 63 | 60.0% |
| 2 to 4 pCi/L | 19 | 18.1% |
| 4 pCi/L and above | 23 | 21.9% |
What these figures count
These are the 105 tests reported to CDC for Santa Cruz 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).
Santa Cruz County, Compared
Santa Cruz County radon figures, compared
Calculated by Radon411Santa Cruz County's 105 reported tests over the 2008 to 2017 laboratory totals had a middle value of 1.2 pCi/L and a maximum of 15.2 pCi/L, and 21.9% reached 4 pCi/L. California as a whole (56 California counties, pooled) comes to 10.3%: 11.6 points lower than here.
Among its state's counties it ranks 6th 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, 63 tests (60.0%) came in under 2 pCi/L, against 76.8% statewide, and 19 tests (18.1%) fell between 2 and 4, against 12.9% statewide. CDC's ten-year totals for Santa Cruz County went from 202 tests (2005 to 2014) to 105 (2008 to 2017), the share going from 19.8% to 21.9%.
EPA's 1993 zone map puts Santa Cruz 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 9.2% in San Mateo County to 14.9% in Monterey County, with Monterey County, Santa Clara County and San Mateo County below Santa Cruz County.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Santa Cruz County, Geology
The ground under Santa Cruz County
PredictedUSGS's geologic map puts all of Santa Cruz 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 | 99.6% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Santa Cruz County beside the ground around it
Across California 0.1% of the land is rated high; none of Santa Cruz County's is. Of the 4 counties that border it, 3 have more moderate-potential ground, San Benito County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Santa Cruz County, Local resources
Radon testing and mitigation in Santa Cruz 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
Santa Cruz County, Questions
Questions about radon in Santa Cruz County
Are radon levels high in Santa Cruz County?
Over the 2008 to 2017 laboratory totals, 21.9% of the radon tests reported to CDC for Santa Cruz County, California were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.2 pCi/L. Of 33 California counties with 30 or more tests for the same period, 5 reported a higher share; pooled, the state comes to 10.3%.
Which counties border Santa Cruz County?
Santa Cruz County borders 4 counties: Santa Clara County, San Mateo County, Monterey County and San Benito County.
Products
Santa Cruz County, Products
Testing a home in Santa Cruz County
In Santa Cruz County, 21.9% of 105 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 Santa Cruz 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
MonitorSafetySiren
Pro4 plug-in radon detector with a display and alarm
- C-NRPP 2024/25: Not included
- Plug-in
- Alarm
- Screen
First reading: Within 48 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Santa Cruz County, Bordering counties
Counties bordering Santa Cruz County
Calculated by Radon411- Radon levels in Monterey CountyEPA zone 2
14.9%at or above 4 pCi/L
Median 0.8 pCi/L · 87 tests · 7.0 points below Santa Cruz County
- Radon levels in Santa Clara CountyEPA zone 2
9.2%at or above 4 pCi/L
Median 0.9 pCi/L · 793 tests · 12.7 points below Santa Cruz County
- Radon levels in San Mateo CountyEPA zone 2
9.2%at or above 4 pCi/L
Median 0.9 pCi/L · 468 tests · 12.7 points below Santa Cruz County
- Radon levels in San Benito CountyEPA zone 2
0.0%at or above 4 pCi/L
Median 0.7 pCi/L · 19 tests · 21.9 points below Santa Cruz County
Santa Cruz County, Cities and towns
Cities and towns in Santa Cruz County
About 258,852 people live in Santa Cruz County by the Census Bureau's estimate for July 1, 2025, 12,906 fewer than in 2020 (−4.7%). That works out to 582 people per square mile of land. Its largest town, Santa Cruz, has 61,797 residents, 23.9% of the total. Together its 4 incorporated places hold 51.6% of those residents; the other 48.4% live outside any of them. Testing is reported here more often than across the state: CDC's 105 reported tests for 2008 to 2017 come to 0.4 for every 1,000 residents (2025 estimate), against 0.2 for California.
From Santa Cruz to Capitola, CDC publishes no figure by town: each reads Santa Cruz County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Santa Cruz | 61,797 | −3.7% | 23.9% |
| Watsonville | 50,716 | −3.3% | 19.6% |
| Scotts Valley | 11,652 | −4.7% | 4.5% |
| Capitola | 9,340 | −5.8% | 3.6% |
4 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).
Santa Cruz County, Homes
Homes in Santa Cruz County
Of Santa Cruz County's 106,635 homes, 64% are detached houses, against 57% across California; 13% are in buildings of five or more homes. Half of its homes were built before 1973, close to California's 1976: 29% date from before 1960 and 12% from 2000 or later. 60% 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 | Santa Cruz County | California |
|---|---|---|
| Housing units | 106,635 | 14,532,683 |
| Detached houses | 64% | 57% |
| In buildings of 5 or more | 13% | 24% |
| Mobile homes | 7% | 4% |
| Built before 1960 | 29% | 27% |
| Built since 2000 | 12% | 18% |
| Middle year built | 1973 | 1976 |
| Owner-occupied | 60% | 56% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.