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 Imperial County, California
EPA puts Imperial County in Zone 3, its lowest radon zone, and only 11 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
2.6%
San Diego County
- San Diego
- 2.6%
- Riverside
- 1.3%
2 of 4 neighbours have 30+ tests, 2008 to 2017
Nearest county
1.3%
Riverside County, 61 miles
- Riverside
- 1.3%
- California
- 10.3%
Share at 4+ pCi/L, 226 tests, 2008 to 2017
Ground above low
None
42.7 pts below California
- Imperial
- 0.0%
- California
- 42.7%
Share of land USGS rates moderate or high potential
Tests reported
15
Too few for a share
- Imperial
- 15
- Needed
- 30
2007 to 2016, 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 Imperial 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
Imperial County, At a glance
Imperial County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
USGS geologic potential: Low across 100% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Imperial County, 2008 to 2017, laboratory
CDC holds 11 reported tests for Imperial County over the 2008 to 2017 laboratory totals, with a median of 0.6 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Imperial County beside the counties around it is how this page reads it.
What these figures count
Only 11 tests were reported to CDC for Imperial 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).
Imperial County, Compared
Imperial County radon figures, compared
Calculated by Radon411CDC's largest figure for Imperial County rests on 15 tests over the 2007 to 2016 laboratory totals, 0 of them at or above 4 pCi/L, so each test moves its share by 6.7 points and no rank or comparison is drawn from it. Results reached as high as 2.5 pCi/L, with a middle value of 0.7 pCi/L.
Of the counties bordering it, 2 have a figure over the 2008 to 2017 laboratory totals: San Diego County reported the largest share at or above 4 pCi/L, 2.6%, and Riverside County the smallest, 1.3%. Farther out, San Bernardino County (133 miles away) at 4.5%, Orange County (146 miles away) at 3.9% and Los Angeles County (187 miles away) at 9.5% 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 Imperial County in Zone 3, its lowest label: a predicted county average under 2 pCi/L. USGS geology rates 100% of the county's land low radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Imperial County, Geology
The ground under Imperial County
PredictedUSGS's geologic map puts all of Imperial County's mapped land in one class: low radon potential. The map puts 66.1% of Imperial County in the area it calls Colorado Desert and 26.5% in Mojave Desert, with one smaller area 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 |
|---|---|---|---|---|
| Colorado Desert | Pleistocene to Holocene marine and (mostly) nonmarine gravel, sand, silt, and clay deposits. | Low | 8 | 66.1% |
| 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 | 26.5% |
| Peninsular Ranges | Granite, metasedimentary and metavolcanic rocks, marine sedimentary rocks, and coastal sediments. | Low | 7 | 7.4% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Imperial County beside the ground around it
Across California 0.1% of the land is rated high; none of Imperial County's is. Of the 4 counties that border it, 1 has more moderate-potential ground, Riverside County the most at 4.2%.
The map rates the ground, not the air in any home.
Local help
Imperial County, Local resources
Radon testing and mitigation in Imperial 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
Imperial County, Questions
Questions about radon in Imperial County
Are radon levels high in Imperial County?
Over the 2008 to 2017 laboratory totals, 0.0% of the radon tests reported to CDC for Imperial County, California were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.6 pCi/L. Of the counties bordering it, 2 have a figure over the 2008 to 2017 laboratory totals: San Diego County reported the largest share at or above 4 pCi/L, 2.6%, and Riverside County the smallest, 1.3%.
Which counties border Imperial County?
Imperial County borders 4 counties: Riverside County, CA, San Diego County, CA, Yuma County, AZ and La Paz County, AZ.
Products
Imperial County, Products
Testing a home in Imperial County
No CDC figure names Imperial County; the nearest county with one, Riverside County (61 miles away), reported 1.3% 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 Imperial County.
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
MonitorX-Sense
XR0A-SR battery digital radon detector with a 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
Imperial County, Bordering counties
Counties bordering Imperial County
Calculated by Radon411- Radon levels in San Diego County, CAEPA zone 3
2.6%at or above 4 pCi/L
Median 0.2 pCi/L · 692 tests
- Radon levels in Riverside County, CAEPA zone 2
1.3%at or above 4 pCi/L
Median 0.6 pCi/L · 226 tests
- Radon levels in Yuma County, AZEPA zone 2
0.0%at or above 4 pCi/L
Median 0.6 pCi/L · 18 tests
- Radon levels in La Paz County, AZEPA zone 2
No CDC figure for 2008 to 2017; its page reads it against its own neighbours.
Imperial County, Cities and towns
Cities and towns in Imperial County
The Census Bureau estimates 181,411 residents in Imperial County for July 1, 2025, 1,879 more than in 2020 (+1.0%). That works out to 43 people per square mile of land. Its largest town, El Centro, has 44,382 residents, 24.5% of the total. Together its 7 incorporated places hold 81.0% of those residents; the other 19.0% live outside any of them. Reported testing is thin here: 15 tests over 2007 to 2016, or 0.1 for every 1,000 residents (2025 estimate), where California as a whole comes to 0.3.
From El Centro to Westmorland, CDC publishes no figure by town: each reads Imperial County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| El Centro | 44,382 | −0.1% | 24.5% |
| Calexico | 38,623 | +0.2% | 21.3% |
| Brawley | 28,008 | +5.7% | 15.4% |
| Imperial | 22,330 | +9.2% | 12.3% |
| Calipatria | 6,012 | −10.6% | 3.3% |
| Holtville | 5,591 | −0.1% | 3.1% |
| Westmorland | 2,015 | +0.2% | 1.1% |
7 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).
Imperial County, Homes
Homes in Imperial County
Of Imperial County's 57,511 homes, 62% are detached houses, against 57% across California; 16% are in buildings of five or more homes. Much of Imperial County is recent building: 30% of its homes have gone up since 2000 and the middle year built is 1988, against 1976 for California. 57% 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 | Imperial County | California |
|---|---|---|
| Housing units | 57,511 | 14,532,683 |
| Detached houses | 62% | 57% |
| In buildings of 5 or more | 16% | 24% |
| Mobile homes | 10% | 4% |
| Built before 1960 | 15% | 27% |
| Built since 2000 | 30% | 18% |
| Middle year built | 1988 | 1976 |
| Owner-occupied | 57% | 56% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.