Napa, CA Radon Mitigation and Testing

Q: What is the average radon level in Napa, CA?

Based on 1 user-submitted tests, the average radon level is 8.00 pCi/L.

Q: What EPA Radon Zone is Napa in?

Napa is in Napa County, EPA Zone 3.

Q: How much does radon mitigation cost in Napa?

Radon mitigation typically costs between $800 and $2,000. Most standard systems fall in the $1,000-$1,500 range.

Avg: 8.00 pCi/L

Napa County

EPA Zone 3

1 user test

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.

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.

Napa, CA Radon Testing

Finding qualified radon testing professionals is the first step toward protecting your home.

Napa, California Radon Levels

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

Radon Level	City	Home Age	Foundation	Submitted
8 pCi/L	Napa, CA	0-20 Years	No Basement/All Slab	Nov 2024

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

Napa Radon Facts

Key details about the radon risk profile for Napa and the 94558 zip code area.

EPA Radon Zone

Zone 3 — Low Risk

County

Napa County, CA

Zip Code

94558

Predicted Screening Level

< 2.0 pCi/L (Zone 3)

Avg. User Submitted Level

8.00 pCi/L

User Tests Submitted

Napa and the 94558 zip code are located in Napa County, which has an EPA assigned Radon Zone of 3. A radon zone of 3 predicts an average indoor radon screening level less than 2 pCi/L. The EPA recommends testing every home regardless of zone classification.

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 with the most user-submitted radon test data in the state.

City	Avg User Radon Level	Submissions
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
Woodland Hills	7.67 pCi/L	3
South Lake Tahoe	6.33 pCi/L	3
Palos Verdes Peninsula	6.00 pCi/L	3
Bishop	5.67 pCi/L	3
Sacramento	4.33 pCi/L	3
Oakland	3.33 pCi/L	3
Fresno	10.00 pCi/L	2
Davis	8.00 pCi/L	2
Palo Alto	6.50 pCi/L	2
Studio City	6.50 pCi/L	2
Menlo Park	5.00 pCi/L	2
Truckee	5.00 pCi/L	2
Walnut Creek	4.00 pCi/L	2
San Diego	3.50 pCi/L	2
San Francisco	3.50 pCi/L	2
Belmont	20.00 pCi/L	1