Fontana, CA Radon Mitigation and Testing

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

Based on 1 user-submitted tests, the average radon level is 6.00 pCi/L.

Q: What EPA Radon Zone is Fontana in?

Fontana is in San Bernardino County, EPA Zone 2.

Q: How much does radon mitigation cost in Fontana?

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

Avg: 6.00 pCi/L

San Bernardino County

EPA Zone 2

1 user test

Located in San Bernardino County within the Riverside metropolitan area, Fontana shows an elevated average radon level of 6.0 pCi/L, significantly above the EPA's 4.0 pCi/L action threshold. The region's alluvial soils and nearby mountain geology create variable radon conditions across zip codes 92335, 92336, and 92337. Despite California's generally moderate radon reputation, these readings demonstrate why testing remains crucial for Inland Empire residents.

6.00

pCi/L average

Above EPA Action Level

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

4.0 EPA

10+

Fontana, CA Radon Mitigation

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

Fontana, CA Radon Testing

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

Fontana, California Radon Levels

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

Radon Level	City	Home Age	Foundation	Submitted
6 pCi/L	Fontana, CA	21-50 Years	—	Feb 2025

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

Fontana Radon Facts

Key details about the radon risk profile for Fontana and the 92335 zip code area.

EPA Radon Zone

Zone 2 — Moderate Risk

County

San Bernardino County, CA

Zip Code

92335

Predicted Screening Level

2–4 pCi/L (Zone 2)

Avg. User Submitted Level

6.00 pCi/L

User Tests Submitted

Fontana and the 92335 zip code are located in San Bernardino 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 Fontana, CA

What is the average radon level in Fontana, CA?

Based on 1 user-submitted test, the average radon level in Fontana is 6.00 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 Fontana in?

Fontana and the 92335 zip code are in San Bernardino 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 Fontana?

Radon mitigation in Fontana 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 Fontana?

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