Is radon high in Santa Rosa, California?

Low. Averaging the model's ZIP-code predictions across Santa Rosa (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 1.4 pCi/L - about 23% below the US average of 1.8 and close to the California average of 1.5. That is below the EPA's 2 pCi/L "consider fixing" threshold, though individual homes still vary. Santa Rosa ranks 162 of 207 California cities on this site.

Which Santa Rosa ZIP codes have the highest radon?

Predictions for the 7 modeled ZIP codes in Santa Rosa range from 1.3 to 1.5 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 0% at or above 2. The city is fairly uniform, so the city-wide number is a reasonable guide for any neighborhood.

Should I test for radon in Santa Rosa?

Yes, once. The EPA recommends testing every home regardless of area. A short-term kit costs little and settles the question for your house; Santa Rosa's low predicted average describes the typical home, not yours.

What does EPA Radon Zone 3 mean for Santa Rosa?

Santa Rosa sits mainly in Sonoma County, which the EPA classifies as Zone 3 - low potential (< 2 pCi/L). The zone map dates from 1993 and covers whole counties. The 2001-2021 model agrees with the zone for the city. Neither replaces a test of your own home.

Radon levels in Santa Rosa, California

LowEPA Zone 3

Predicted long-term basement average of 1.4 pCi/L (model estimate) across the 7 modeled ZIP codes in Santa Rosa - about 23% below the US average of 1.8, close to the California average of 1.5. Ranked #162 of 207 California cities on this site. Most of the city lies in Sonoma County.

Test Santa Rosa, CA once anyway - radon varies house to house

The predicted basement average here is 1.4 pCi/L, below the EPA's 2 pCi/L "consider fixing" threshold. That's good news for the area - but the EPA still recommends every home be tested, because foundation cracks, soil pockets and ventilation make one house very different from its neighbor. One inexpensive kit settles it.

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Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. How the numbers work.

1.4 ± 0.06

pCi/L predicted basement mean (model SD)

0.7 ± 0.07

pCi/L predicted upstairs (above-ground) mean

1.3-1.5

range of ZIP-level basement predictions in the city

of Santa Rosa ZIPs predicted ≥ 4 pCi/L (0% ≥ 2)

What this means for Santa Rosa

The typical Santa Rosa home is predicted below 2 pCi/L, the lowest band. That describes the average house; the ZIP-level predictions inside the city still span 1.3 to 1.5 pCi/L.

The city figure is not a separate estimate: it is the mean of the model's ZIP-code predictions, weighted by the share of the city's land in each ZIP (Census 2020 ZCTA-to-place relationship file). The 1993 EPA zone (3) for Sonoma and the 2001-2021 model agree here.

Comparable California cities: Anaheim (1.4), Roseville (1.4), El Monte (1.4), Inglewood (1.4).

ZIP codes in Santa Rosa

ZIPs that overlap the city, largest share of its land first. Predicted basement and upstairs means are model estimates; ZIPs the model does not cover show a dash.

ZIP	Share of city	Basement	Upstairs	Grade
95409	20%	1.5 ± 0.06	0.7	Low
95404	19%	1.4 ± 0.06	0.7	Low
95407	17%	1.3 ± 0.07	0.6	Low
95403	17%	1.4 ± 0.06	0.7	Low
95401	13%	1.3 ± 0.06	0.6	Low
95405	12%	1.4 ± 0.06	0.7	Low
95472	3%	1.5 ± 0.07	0.7	Low

Testing help in California

California's radon program page is at www.cdph.ca.gov; it lists testing and certified-mitigator guidance. EPA state radon contacts page. If a test comes back at 4 pCi/L or higher, mitigation typically costs $800-$2,500 installed; use EPA find-a-professional and read the mitigation guide.

Santa Rosa radon questions

Is radon high in Santa Rosa, California?: Low. Averaging the model's ZIP-code predictions across Santa Rosa (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 1.4 pCi/L - about 23% below the US average of 1.8 and close to the California average of 1.5. That is below the EPA's 2 pCi/L "consider fixing" threshold, though individual homes still vary. Santa Rosa ranks 162 of 207 California cities on this site.
Which Santa Rosa ZIP codes have the highest radon?: Predictions for the 7 modeled ZIP codes in Santa Rosa range from 1.3 to 1.5 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 0% at or above 2. The city is fairly uniform, so the city-wide number is a reasonable guide for any neighborhood.
Should I test for radon in Santa Rosa?: Yes, once. The EPA recommends testing every home regardless of area. A short-term kit costs little and settles the question for your house; Santa Rosa's low predicted average describes the typical home, not yours.
What does EPA Radon Zone 3 mean for Santa Rosa?: Santa Rosa sits mainly in Sonoma County, which the EPA classifies as Zone 3 - low potential (< 2 pCi/L). The zone map dates from 1993 and covers whole counties. The 2001-2021 model agrees with the zone for the city. Neither replaces a test of your own home.

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