Short-term kit
Air Chek Short-Term radon test kit you hang, lab fee included
- Lab fee included
In home: 72 to 168 hours
Locations and reports
Radon Levels in Kern County, California
EPA puts Kern County in Zone 2, its middle radon zone, and most reported tests there come back low, though 11.6% of 121 (2008 to 2017, laboratory totals) reached 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
11.6%
1.3 pts above CA
- Kern
- 11.6%
- California
- 10.3%
121 tests, 2008 to 2017
Median result
1.8pCi/L
Below action level
- Kern
- 1.8 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
121
18th of 33 by tests
- Kern
- 121
- 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
15 of 33
Middle half
- Kern
- 11.6%
- El Dorado
- 30.3%
By share, of 33 with 30+ tests
Read a result for Kern County
Starts at Kern County's median, 1.8 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 1.8 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. Kern County's median reported result, 2008 to 2017.
The data
Kern County, At a glance
Kern County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Kern County is a
USGS geologic potential: Moderate across 55% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Kern County, 2008 to 2017, laboratory
Under 2 pCi/L: 53%2 to 4 pCi/L: 35%4 pCi/L and above: 12%
Of 121 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 64 | 52.9% |
| 2 to 4 pCi/L | 43 | 35.5% |
| 4 pCi/L and above | 14 | 11.6% |
What these figures count
These are the 121 tests reported to CDC for Kern 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).
Kern County, Compared
Kern County radon figures, compared
Calculated by Radon41111.6% of its 121 tests over the 2008 to 2017 laboratory totals were at or above 4 pCi/L. That is 1.3 points above the 10.3% pooled from 56 California counties.
Ordered from highest share down, it comes 15th of 33 California counties with 30 or more tests for the same period. Nationally, every county with a figure for the same period pools to 35.7%; Kern County sits 24.1 points below it.
Next door, the shares run from 4.5% in San Bernardino County to 23.8% in Tulare County, with Los Angeles County and San Bernardino County below Kern County. Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 11.6% share point the same way here.
Half the tests came in under 1.8 pCi/L and half over it; the single highest reached 290.4 pCi/L. The rest split 52.9% under 2 pCi/L and 35.5% from 2 to 4 (California: 76.8% and 12.9%).
CDC's ten-year totals for Kern County went from 123 tests (2005 to 2014) to 121 (2008 to 2017), the share going from 11.4% to 11.6%.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Kern County, Geology
The ground under Kern County
PredictedUSGS's geologic map splits Kern County: 55.2% of its land is moderate radon potential and 44.8% low. The map puts 37.6% of Kern County in the area it calls Sierra Nevada and 27.1% in Great Valley, with 3 smaller areas beside them. USGS gives the first a radon index of 9, in the moderate band (9 to 11), and the second 8, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| 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 | 37.6% |
| Great Valley | Quaternary alluvial gravel, sand, silt, clay. | Low | 8 | 27.1% |
| Mojave Desert | Precambrian and Paleozoic metamorphosed and unmetamorphosed sedimentary rocks, Mesozoic and Tertiary intrusive rocks, Tertiary sedimentary and volcanic rocks, and significant eolian deposits. | Low | 8 | 17.7% |
| 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 | 11.1% |
| 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 | 6.5% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Kern County beside the ground around it
Across California 0.1% of the land is rated high; none of Kern County's is. Of the 8 counties that border it, 1 has more high-potential ground, Inyo County the most at 1.0%.
The map rates the ground, not the air in any home.
Local help
Kern County, Local resources
Radon testing and mitigation in Kern 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
Kern County, Questions
Questions about radon in Kern County
Are radon levels high in Kern County?
Over the 2008 to 2017 laboratory totals, 11.6% of the radon tests reported to CDC for Kern County, California were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.8 pCi/L. Of 33 California counties with 30 or more tests for the same period, 14 reported a higher share; pooled, the state comes to 10.3%.
Which counties border Kern County?
Kern County borders 8 counties: Ventura County, Tulare County, Los Angeles County, Kings County, Santa Barbara County, San Luis Obispo County, Inyo County and San Bernardino County.
Products
Kern County, Products
Testing a home in Kern County
In Kern County, 11.6% of 121 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 Kern County; a long-term test tells the year-round average.
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
MonitorAranet
Radon One battery digital radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- 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
Kern County, Bordering counties
Counties bordering Kern County
Calculated by Radon411- Radon levels in Inyo CountyEPA zone 2
50.0%at or above 4 pCi/L
Median 4.0 pCi/L · 14 tests · 38.4 points above Kern County
- Radon levels in Tulare CountyEPA zone 2
23.8%at or above 4 pCi/L
Median 1.7 pCi/L · 80 tests · 12.2 points above Kern County
- Radon levels in Santa Barbara CountyEPA zone 1
17.6%at or above 4 pCi/L
Median 1.2 pCi/L · 421 tests · 6.0 points above Kern County
- Radon levels in San Luis Obispo CountyEPA zone 2
12.5%at or above 4 pCi/L
Median 1.0 pCi/L · 80 tests · 0.9 points above Kern County
- Radon levels in Ventura CountyEPA zone 1
11.9%at or above 4 pCi/L
Median 1.0 pCi/L · 335 tests · 0.3 points above Kern County
- Radon levels in Los Angeles CountyEPA zone 2
9.5%at or above 4 pCi/L
Median 0.7 pCi/L · 2,363 tests · 2.1 points below Kern County
- Radon levels in San Bernardino CountyEPA zone 2
4.5%at or above 4 pCi/L
Median 0.7 pCi/L · 178 tests · 7.1 points below Kern County
- Radon levels in Kings CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 1.7 pCi/L · 2 tests · 11.6 points below Kern County
Kern County, Cities and towns
Cities and towns in Kern County
The Census Bureau estimates 927,068 residents in Kern County for July 1, 2025, 21,108 more than in 2020 (+2.3%). That works out to 114 people per square mile of land. Its largest town, Bakersfield, has 422,165 residents, 45.5% of the total. Together its 11 incorporated places hold 67.0% of those residents; the other 33.0% live outside any of them. Reported testing is thin here: 121 tests over 2008 to 2017, or 0.1 for every 1,000 residents (2025 estimate), where California as a whole comes to 0.2.
From Bakersfield to Maricopa, CDC publishes no figure by town: each reads Kern County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Bakersfield | 422,165 | +4.2% | 45.5% |
| Delano | 52,334 | +4.9% | 5.6% |
| Ridgecrest | 28,333 | +1.3% | 3.1% |
| Wasco | 26,525 | +4.5% | 2.9% |
| Shafter | 23,871 | +19.0% | 2.6% |
| Arvin | 19,820 | +1.6% | 2.1% |
| McFarland | 14,709 | +3.8% | 1.6% |
| California City | 13,300 | −11.8% | 1.4% |
| Tehachapi | 11,852 | −8.9% | 1.3% |
| Taft | 6,995 | −6.5% | 0.8% |
| Maricopa | 1,018 | −0.3% | 0.1% |
11 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).
Kern County, Homes
Homes in Kern County
Of Kern County's 304,481 homes, 72% are detached houses, against 57% across California; 9% are in buildings of five or more homes. Much of Kern County is recent building: 27% of its homes have gone up since 2000 and the middle year built is 1984, against 1976 for California. 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 | Kern County | California |
|---|---|---|
| Housing units | 304,481 | 14,532,683 |
| Detached houses | 72% | 57% |
| In buildings of 5 or more | 9% | 24% |
| Mobile homes | 8% | 4% |
| Built before 1960 | 18% | 27% |
| Built since 2000 | 27% | 18% |
| Middle year built | 1984 | 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.