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Napa, CA Radon Levels

Check local Napa radon levels and find certified testing and mitigation professionals to keep your home safe


Napa, CA Radon Facts

EPA Radon Zone Zone 3 — Low Risk < 2.0 pCi/L (Zone 3)
County Napa County, CA
Zip Code 94558
Avg. User Level 8.00 pCi/L
User Tests 1

Situated in Napa County in California's famous wine region, Napa shows concerning radon levels that exceed EPA recommendations. Recent testing across zip codes 94558 and 94559 reveals an average reading of 8.0 pCi/L, which doubles the EPA's 4.0 pCi/L action threshold and likely reflects the area's complex geology of volcanic soils over fractured bedrock.

8.00
pCi/L average
Above EPA Action Level

Based on 1 user-submitted radon test for homes in Napa, CA. The EPA recommends taking action at or above 4.0 pCi/L.

0
4.0 EPA
10+

Napa, CA Radon Mitigation

Professional radon mitigation is the most effective way to permanently lower radon levels and protect your household.

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Napa, CA Radon Levels

User-submitted radon test readings from homes in the Napa area.

Radon LevelCityHome AgeFoundation
8 pCi/L Napa, CA 0-20 Years No Basement/All Slab

Have a radon test result for Napa? Submit your reading to help other homeowners.

Radon FAQ for Napa, CA

What is the average radon level in Napa, CA?
Based on 1 user-submitted test, the average radon level in Napa is 8.00 pCi/L. This exceeds the EPA's recommended action level of 4.0 pCi/L, and radon testing is recommended for all homes in the area.
What EPA Radon Zone is Napa in?
Napa and the 94558 zip code are in Napa County, which has an EPA assigned Radon Zone of 3. A zone of 3 predicts an average indoor radon screening level less than 2 pCi/L.
How much does radon mitigation cost in Napa?
Radon mitigation in Napa typically costs between $800 and $2,000. Most homes with standard basements can be mitigated with a sub-slab depressurization system in the $1,000–$1,500 range. Factors that can increase cost include complex foundations, crawl spaces, or very high radon levels.
Should I test for radon if I'm buying a home in Napa?
Yes. Radon testing should be part of every home purchase. A short-term radon test is typically included as part of the home inspection process and costs $150–$250. If elevated levels are found, you can negotiate mitigation as part of the sale.

Most Active Radon Markets in California

Cities in California with the most user-submitted radon test data, ranked by number of submissions.

CityAvg User Radon LevelSubmissions
Los Angeles 7.83 pCi/L 6
Mammoth Lakes 10.80 pCi/L 5
San Jose 4.20 pCi/L 5
Rancho Palos Verdes 8.00 pCi/L 4
Bishop 6.25 pCi/L 4
Oakland 5.00 pCi/L 4
Woodland Hills 7.67 pCi/L 3
South Lake Tahoe 6.33 pCi/L 3
Palos Verdes Peninsula 6.00 pCi/L 3
Sacramento 4.33 pCi/L 3