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Radon Levels in Sacramento County, California

EPA puts Sacramento County in Zone 3, its lowest radon zone, and most reported tests there come back low, though 7.7% of 194 (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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    7.7%

    2.6 pts below CA

    Sacramento
    7.7%
    California
    10.3%

    194 tests, 2008 to 2017

  • Median result

    0.9pCi/L

    Below action level

    Sacramento
    0.9 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    194

    15th of 33 by tests

    Sacramento
    194
    Los Angeles
    2,363

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 3

    Lower potential

    1. 1
    2. 2
    3. Zone 3

    1 highest, 3 lowest

    EPA predicts under 2 pCi/L indoors

  • Rank in California

    23 of 33

    Middle half

    Sacramento
    7.7%
    El Dorado
    30.3%

    By share, of 33 with 30+ tests

Read a result for Sacramento County

Starts at Sacramento County's median, 0.9 pCi/L

0.9pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 0.9 pCi/L

Below 2 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 4 and aboveEPA says fix it

This result is below 2 pCi/L, the level at which EPA says a fix should be considered. Sacramento County's median reported result, 2008 to 2017.

Interpret this reading

The data

Sacramento County, At a glance

Sacramento County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

is EPA's lowest class, and its forecast for Sacramento County as a whole is an average indoor of less than 2 pCi/L (less than 75 Bq/m³). A low zone clears no address in it: homes above EPA's turn up in all three zones.

USGS geologic potential: Low across 78% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Sacramento County, 2008 to 2017, laboratory

Reported results by concentration band, Sacramento County, 2008 to 2017, laboratory
Under 2 pCi/L: 78%2 to 4 pCi/L: 14%4 pCi/L and above: 8%

Of 194 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Sacramento County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L15278.4%
2 to 4 pCi/L2713.9%
4 pCi/L and above157.7%
What these figures count

These are the 194 tests reported to CDC for Sacramento 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).

How to read these figures

Sacramento County, Compared

Sacramento County radon figures, compared

Calculated by Radon411

Sacramento County reports fewer high tests than California overall. 7.7% of its 194 tests over the 2008 to 2017 laboratory totals were at or above 4 pCi/L. That is 2.6 points below the 10.3% pooled from 56 California counties.

Ordered from highest share down, it comes 23rd 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%; Sacramento County sits 28.0 points below it.

Next door, the shares run from 2.1% in Yolo County to 30.3% in El Dorado County, with Placer County and Yolo County below Sacramento County. Zone 3 on EPA's map (predicted average under 2 pCi/L) and a 7.7% share point the same way here.

Half the tests came in under 0.9 pCi/L and half over it; the single highest reached 20.6 pCi/L. The rest split 78.4% under 2 pCi/L and 13.9% from 2 to 4 (California: 76.8% and 12.9%).

CDC's ten-year totals for Sacramento County went from 180 tests (2005 to 2014) to 194 (2008 to 2017), the share going from 11.7% to 7.7%.

Sacramento County against California, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Sacramento County
Sacramento County1947.7%0.9 pCi/LThis county
California, pooled56 counties, pooled9,41510.3%Not pooled+2.6 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+28.0 points
Nevada Countyhighest in the state26025.0%2.0 pCi/L+17.3 points
Sonoma Countylowest in the state1310.8%0.5 pCi/L−6.9 points
Sutter County, CAborders it742.9%1.9 pCi/L+35.2 points
El Dorado County, CAborders it27430.3%1.6 pCi/L+22.6 points
Amador County, CAborders it3627.8%2.3 pCi/L+20.1 points
Solano County, CAborders it3815.8%0.9 pCi/L+8.1 points
San Joaquin County, CAborders it7414.9%1.4 pCi/L+7.2 points
Contra Costa County, CAborders it2858.8%0.9 pCi/L+1.1 points
Placer County, CAborders it2837.4%1.1 pCi/L−0.3 points
Yolo County, CAborders it482.1%0.9 pCi/L−5.6 points
Where Sacramento County's reported results fell, 2008 to 2017, laboratory, beside California and the United States
ResultSacramento County testsSacramento County shareCalifornia shareU.S. shareAgainst California
Under 2 pCi/L15278.4%76.8%39.6%+1.6 points
2 to 4 pCi/L2713.9%12.9%24.7%+1.0 points
4 pCi/L and above157.7%10.3%35.7%−2.6 points
Sacramento County ranked among the 33 California counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Napa County18 of 335710.5%0.9 pCi/L
Los Angeles County19 of 332,3639.5%0.7 pCi/L
Santa Clara County20 of 337939.2%0.9 pCi/L
San Mateo County21 of 334689.2%0.9 pCi/L
Contra Costa County22 of 332858.8%0.9 pCi/L
Sacramento County23 of 331947.7%0.9 pCi/L
Placer County24 of 332837.4%1.1 pCi/L
Alameda County25 of 334786.7%0.7 pCi/L
Marin County26 of 33956.3%0.8 pCi/L
San Bernardino County27 of 331784.5%0.7 pCi/L
Orange County28 of 334313.9%0.7 pCi/L
Sacramento County ten-year laboratory totals, against California's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestCalifornia, pooledChange from the row before
2008 to 20171947.7%0.9 pCi/L20.6 pCi/L10.3%−0.7 points
2007 to 20162038.4%0.8 pCi/L20.6 pCi/L10.6%−3.7 points
2006 to 201518212.1%0.8 pCi/L20.6 pCi/L10.6%+0.4 points
2005 to 201418011.7%0.8 pCi/L13.7 pCi/L10.0%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Sacramento County, Geology

The ground under Sacramento County

Predicted

Most of the ground under Sacramento County is one class on USGS's geologic map: 78.0% of its land is low radon potential, with 20.3% moderate. The map puts 78.0% of Sacramento County in the area it calls Great Valley and 20.3% in Sierra Nevada. USGS gives the first a radon index of 8, in the low band (5 to 8), and the second 9, in the moderate band (9 to 11).

USGS's geologic areas under Sacramento County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Great ValleyQuaternary alluvial gravel, sand, silt, clay.Low878.0%
Sierra NevadaNorthern Sierra Nevada is underlain primarily by Paleozoic and Mesozoic metamorphic rocks. Granitic rocks predominate in the southern Sierrra Nevada , with lesser Mesozoic metamorphic rocks.Moderate920.3%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Sacramento County beside the ground around it

Across California 0.1% of the land is rated high; none of Sacramento County's is. Of the 8 counties that border it, 4 have more moderate-potential ground, Amador County the most at 100%.

Share of land by USGS radon potential: Sacramento County, the 8 counties bordering it and California
AreaEPA zoneLow potentialModerate potentialHigh potential
Sacramento CountyZone 378.0%20.3%None
Amador CountyZone 2None100%None
San Joaquin CountyZone 384.6%15.0%None
Solano CountyZone 394.2%NoneNone
Yolo CountyZone 3100%NoneNone
Sutter CountyZone 3100%NoneNone
El Dorado CountyZone 2None100%None
Contra Costa CountyZone 221.8%74.1%None
Placer CountyZone 27.7%92.3%None
California58 counties, pooled by land areaVaries57.2%42.6%0.1%

The map rates the ground, not the air in any home.

Local help

Sacramento County, Local resources

Radon testing and mitigation in Sacramento County

What California's program says
Phone
1-800-745-7236
Email
Radonprogram@cdph.ca.gov
Licensing of radon professionals
The Radon Program certifies all radon service providers operating in California.

What it means

Sacramento County, Questions

Questions about radon in Sacramento County

Are radon levels high in Sacramento County?

Over the 2008 to 2017 laboratory totals, 7.7% of the radon tests reported to CDC for Sacramento County, California were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.9 pCi/L. Of 33 California counties with 30 or more tests for the same period, 22 reported a higher share; pooled, the state comes to 10.3%.

Which counties border Sacramento County?

Sacramento County borders 8 counties: Amador County, San Joaquin County, Solano County, Yolo County, Sutter County, El Dorado County, Contra Costa County and Placer County.

Products

Sacramento County, Products

Testing a home in Sacramento County

In Sacramento County, 7.7% of 194 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 10.3% pooled across California. 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 Sacramento County.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Sacramento County homes, compared

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Sacramento County, Bordering counties

Counties bordering Sacramento County

Calculated by Radon411

Sacramento County, Cities and towns

Cities and towns in Sacramento County

The Census Bureau estimates 1,618,460 residents in Sacramento County for July 1, 2025, 31,691 more than in 2020 (+2.0%). Packed into its land, that is 1,677 people per square mile. Its largest town, Sacramento, has 536,449 residents, 33.1% of the total. Together its 7 incorporated places hold 62.7% of those residents; the other 37.3% live outside any of them. Reported testing is thin here: 194 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 Sacramento to Isleton, CDC publishes no figure by town: each reads Sacramento County's.

The cities and towns in Sacramento County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Sacramento536,449+2.1%33.1%
Elk Grove185,007+4.8%11.4%
Folsom91,983+13.7%5.7%
Rancho Cordova87,554+9.9%5.4%
Citrus Heights86,348−1.4%5.3%
Galt26,964+5.1%1.7%
Isleton775−2.5%Under 0.1%

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).

Sacramento County, Homes

Homes in Sacramento County

Of Sacramento County's 593,616 homes, 65% are detached houses, against 57% across California; 19% are in buildings of five or more homes. Half of its homes were built before 1980, close to California's 1976: 20% date from before 1960 and 21% from 2000 or later. 59% 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 in Sacramento County, California, 2019 to 2023
HomesSacramento CountyCalifornia
Housing units593,61614,532,683
Detached houses65%57%
In buildings of 5 or more19%24%
Mobile homes2%4%
Built before 196020%27%
Built since 200021%18%
Middle year built19801976
Owner-occupied59%56%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.