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 Los Angeles County, California
EPA puts Los Angeles County in Zone 2, its middle radon zone, and most reported tests there come back low, though 9.5% of 2,363 (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
9.5%
0.8 pts below CA
- Los Angeles
- 9.5%
- California
- 10.3%
2,363 tests, 2008 to 2017
Median result
0.7pCi/L
Below action level
- Los Angeles
- 0.7 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
2,363
Most tested in California
- 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
19 of 33
Middle half
- Los Angeles
- 9.5%
- El Dorado
- 30.3%
By share, of 33 with 30+ tests
Read a result for Los Angeles County
Starts at Los Angeles County's median, 0.7 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 0.7 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. Los Angeles County's median reported result, 2008 to 2017.
The data
Los Angeles County, At a glance
Los Angeles County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Los Angeles County is a
USGS geologic potential: Low across 55% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Los Angeles County, 2008 to 2017, laboratory
Under 2 pCi/L: 80%2 to 4 pCi/L: 10%4 pCi/L and above: 10%
Of 2,363 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 1,898 | 80.3% |
| 2 to 4 pCi/L | 241 | 10.2% |
| 4 pCi/L and above | 224 | 9.5% |
What these figures count
These are the 2,363 tests reported to CDC for Los Angeles 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).
Los Angeles County, Compared
Los Angeles County radon figures, compared
Calculated by Radon411Los Angeles County reports fewer high tests than California overall. 9.5% of its 2,363 tests over the 2008 to 2017 laboratory totals were at or above 4 pCi/L. That is 0.8 points below the 10.3% pooled from 56 California counties.
Ordered from highest share down, it comes 19th 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%; Los Angeles County sits 26.2 points below it.
Next door, the shares run from 3.9% in Orange County to 11.9% in Ventura County, with San Bernardino County and Orange County below Los Angeles County. The reported tests do not follow EPA's Zone 2 label for Los Angeles County (predicted average between 2 and 4 pCi/L): 9.5% of them reached 4 pCi/L, fewer than that label suggests.
Half the tests came in under 0.7 pCi/L and half over it; the single highest reached 363.7 pCi/L. The rest split 80.3% under 2 pCi/L and 10.2% from 2 to 4 (California: 76.8% and 12.9%).
CDC's ten-year totals for Los Angeles County went from 2,302 tests (2005 to 2014) to 2,363 (2008 to 2017), the share going from 9.2% to 9.5%.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Los Angeles County, Geology
The ground under Los Angeles County
PredictedUSGS's geologic map splits Los Angeles County: 54.8% of its land is low radon potential and 44.5% moderate. The map puts 44.2% of Los Angeles County in the area it calls Transverse Ranges and 30.3% in Mojave Desert, with 2 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 |
|---|---|---|---|---|
| Transverse Ranges | Precambrian metamorphic rocks and Mesozoic granitic rocks, and the western part is underlain by Cretaceous to Pliocene marine sedimentary rocks. | Moderate | 9 | 44.2% |
| 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 | 30.3% |
| Peninsular Ranges | Granite, metasedimentary and metavolcanic rocks, marine sedimentary rocks, and coastal sediments. | Low | 7 | 21.4% |
| Channel Islands | Tertiary marine sedimentary, volcanic, igneous, and metamorphic rocks. | Low | 7 | 3.1% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Los Angeles County beside the ground around it
Across California 0.1% of the land is rated high; none of Los Angeles County's is. Of the 4 counties that border it, 2 have more moderate-potential ground, Ventura County the most at 97.8%.
The map rates the ground, not the air in any home.
Local help
Los Angeles County, Local resources
Radon testing and mitigation in Los Angeles County
Listed radon businesses with an address in Los Angeles 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.
Listed radon professionals by town: Torrance
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
Los Angeles County, Questions
Questions about radon in Los Angeles County
Are radon levels high in Los Angeles County?
Over the 2008 to 2017 laboratory totals, 9.5% of the radon tests reported to CDC for Los Angeles County, California were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.7 pCi/L. Of 33 California counties with 30 or more tests for the same period, 18 reported a higher share; pooled, the state comes to 10.3%.
Which counties border Los Angeles County?
Los Angeles County borders 4 counties: Orange County, Ventura County, Kern County and San Bernardino County.
Products
Los Angeles County, Products
Testing a home in Los Angeles County
In Los Angeles County, 9.5% of 2,363 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 Los Angeles 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
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
Los Angeles County, Bordering counties
Counties bordering Los Angeles County
Calculated by Radon411- Radon levels in Ventura CountyEPA zone 1
11.9%at or above 4 pCi/L
Median 1.0 pCi/L · 335 tests · 2.4 points above Los Angeles County
- Radon levels in Kern CountyEPA zone 2
11.6%at or above 4 pCi/L
Median 1.8 pCi/L · 121 tests · 2.1 points above Los Angeles County
- Radon levels in San Bernardino CountyEPA zone 2
4.5%at or above 4 pCi/L
Median 0.7 pCi/L · 178 tests · 5.0 points below Los Angeles County
- Radon levels in Orange CountyEPA zone 3
3.9%at or above 4 pCi/L
Median 0.7 pCi/L · 431 tests · 5.6 points below Los Angeles County
Los Angeles County, Cities and towns
Cities and towns in Los Angeles County
About 9,694,934 people live in Los Angeles County by the Census Bureau's estimate for July 1, 2025, 301,576 fewer than in 2020 (−3.0%). Packed into its land, that is 2,388 people per square mile. Its largest town, Los Angeles, has 3,869,089 residents, 39.9% of the total. Together its 88 incorporated places hold 90.3% of those residents; the other 9.7% live outside any of them. CDC's 2,363 reported tests for 2008 to 2017 work out to 0.2 per 1,000 residents (2025 estimate), close to California's 0.2.
From Los Angeles to Industry, CDC publishes no figure by town: each reads Los Angeles County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Los Angeles | 3,869,089 | −0.7% | 39.9% |
| Long Beach | 450,469 | −3.2% | 4.6% |
| Santa Clarita | 228,430 | −1.7% | 2.4% |
| Glendale | 187,160 | −4.5% | 1.9% |
| Lancaster | 170,084 | −1.8% | 1.8% |
| Palmdale | 161,845 | −4.2% | 1.7% |
| Pomona | 147,807 | −2.1% | 1.5% |
| Torrance | 138,391 | −5.5% | 1.4% |
| Pasadena | 135,804 | −2.6% | 1.4% |
| Downey | 108,468 | −4.8% | 1.1% |
| West Covina | 105,301 | −3.5% | 1.1% |
| El Monte | 105,075 | −3.7% | 1.1% |
- Burbank
- Inglewood
- Norwalk
- Carson
- Compton
- Santa Monica
- South Gate
- Whittier
- Hawthorne
- Alhambra
- Lakewood
- Bellflower
- Baldwin Park
- Redondo Beach
- Lynwood
- Montebello
- Pico Rivera
- Gardena
- Monterey Park
- Arcadia
- Diamond Bar
- Huntington Park
- Paramount
- Glendora
The other 52 places in Los Angeles County
- Rosemead
- Covina
- Azusa
- Cerritos
- La Mirada
- Rancho Palos Verdes
- Culver City
- Monrovia
- San Gabriel
- Bell Gardens
- La Puente
- Claremont
- Temple City
- West Hollywood
- Manhattan Beach
- San Dimas
- Bell
- Beverly Hills
- La Verne
- Lawndale
- Walnut
- South Pasadena
- Maywood
- San Fernando
- Duarte
- Calabasas
- Cudahy
- Lomita
- La Cañada Flintridge
- Agoura Hills
- South El Monte
- Santa Fe Springs
- Hermosa Beach
- El Segundo
- Artesia
- Hawaiian Gardens
- Palos Verdes Estates
- San Marino
- Commerce
- Signal Hill
- Sierra Madre
- Malibu
- Rolling Hills Estates
- Westlake Village
- La Habra Heights
- Avalon
- Hidden Hills
- Rolling Hills
- Irwindale
- Bradbury
- Vernon
- Industry
88 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).
Los Angeles County, Homes
Homes in Los Angeles County
Los Angeles County has 3,624,084 homes, and many share a building: 36% are in buildings of five or more, 48% are detached houses, against 57% across California. The homes are older than California's as a whole: half were built before 1965 (1976 for California), and 43% date from before 1960. Most occupied homes here are rented: owners live in 46% (California: 56%). A tenant can run a test; a fix is the landlord's to make.
| Homes | Los Angeles County | California |
|---|---|---|
| Housing units | 3,624,084 | 14,532,683 |
| Detached houses | 48% | 57% |
| In buildings of 5 or more | 36% | 24% |
| Mobile homes | 2% | 4% |
| Built before 1960 | 43% | 27% |
| Built since 2000 | 11% | 18% |
| Middle year built | 1965 | 1976 |
| Owner-occupied | 46% | 56% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.