San Jose, CA Radon Mitigation and Testing

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

Based on 5 user-submitted tests, the average radon level is 4.20 pCi/L.

Q: What EPA Radon Zone is San Jose in?

San Jose is in Santa Clara County, EPA Zone 2.

Q: How much does radon mitigation cost in San Jose?

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

Avg: 4.20 pCi/L

Santa Clara County

EPA Zone 2

5 user tests

San Jose is located in Santa Clara County, California. With 5 user-submitted readings averaging 4.20 pCi/L, the area exceeds the EPA's 4.0 pCi/L action threshold, and testing is strongly recommended for homeowners in the 95101 zip code.

4.20

pCi/L average

Above EPA Action Level

Based on 5 user-submitted radon tests for homes in San Jose, CA. The EPA recommends taking action at or above 4.0 pCi/L.

4.0 EPA

10+

San Jose, CA Radon Mitigation

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

San Jose, CA Radon Testing

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

San Jose, California Radon Levels

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

Radon Level	City	Home Age	Foundation	Submitted
4 pCi/L	San Jose, CA	—	No Basement/All Slab	Dec 2025
4 pCi/L	San Jose, CA	51-99 Years	No Basement/All Crawl Space	Nov 2025
5 pCi/L	San Jose, CA	51-99 Years	No Basement/All Slab	Jan 2024
4 pCi/L	San Jose, CA	21-50 Years	No Basement/All Crawl Space	Sep 2020

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

San Jose Radon Facts

Key details about the radon risk profile for San Jose and the 95101 zip code area.

EPA Radon Zone

Zone 2 — Moderate Risk

County

Santa Clara County, CA

Zip Code

95101

Predicted Screening Level

2–4 pCi/L (Zone 2)

Avg. User Submitted Level

4.20 pCi/L

User Tests Submitted

San Jose and the 95101 zip code are located in Santa Clara County, which has an EPA assigned Radon Zone of 2. A radon zone of 2 predicts an average indoor radon screening level between 2 and 4 pCi/L. The EPA recommends testing every home regardless of zone classification.

Radon FAQ for San Jose, CA

What is the average radon level in San Jose, CA?

Based on 5 user-submitted tests, the average radon level in San Jose is 4.20 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 San Jose in?

San Jose and the 95101 zip code are in Santa Clara County, which has an EPA assigned Radon Zone of 2. A zone of 2 predicts an average indoor radon screening level between 2 and 4 pCi/L.

How much does radon mitigation cost in San Jose?

Radon mitigation in San Jose 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 San Jose?

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