California — 13M metro

Radon in Los Angeles,
CA

Los Angeles County is EPA Zone 3 (low risk). California Air Resources Board data shows most LA metro homes testing below 2 pCi/L. Inland areas (Riverside County, San Bernardino foothills) show somewhat higher readings due to granite mountain geology.

Risk Level

Low Risk

0.4–1.5 pCi/L

Typical range (area avg.)

EPA action level: 4 pCi/L

Why Los Angeles Has Low Risk Radon

The LA basin is underlain by marine sedimentary deposits and alluvial fill that are low in uranium. However, homes in canyon communities and foothills areas (Pasadena foothills, Malibu Canyon, San Gabriel Mountains communities) sit closer to granitic terrain with higher radon potential.

Local Housing and Radon Risk

LA's mild climate and open-construction style (large window-to-wall ratios, frequent natural ventilation) naturally dilute radon. Slab construction dominates in the basin. However, hillside homes with cut-and-fill foundations or partial basements are worth testing.

Testing Advice for Los Angeles Residents

LA homeowners in canyon communities (Laurel Canyon, Benedict Canyon, Topanga Canyon) and foothill areas (Pasadena, Sierra Madre, Monrovia) should prioritize testing over those in the flat LA basin. California CDPH provides radon resources.

How to Test Your Los Angeles Home

Step 1: Choose Your Test Type

For initial screening, a charcoal short-term test kit ($12–$25) placed for 48–96 hours provides a quick result. For the most accurate reading, a long-term alpha-track test ($20–$35) left in place for 90+ days accounts for seasonal variation — especially important in Los Angeles's climate.

Step 2: Place the Test Correctly

Test in your lowest livable level — basement if you have one, otherwise the first floor. Keep the test 20 inches from the floor, away from windows and exterior walls. Close windows and doors 12 hours before and during the test for accurate results.

Step 3: Interpret Your Results

Below 2 pCi/L: low concern, retest every 2 years. 2–4 pCi/L: consider mitigation, retest in 2 years. 4 pCi/L or higher: the EPA recommends mitigation. Above 8 pCi/L: prioritize mitigation promptly.

Step 4: Hire a Certified Mitigator if Needed

If your test result is at or above 4 pCi/L, hire a certified radon mitigator. In California, always verify your contractor's state certification. Sub-slab depressurization — the most effective mitigation method — typically costs $1,000–$2,000 installed (higher CA labor costs) in the Los Angeles area.

Frequently Asked Questions — Radon in Los Angeles

Is radon a real problem in Los Angeles?

Yes. Los Angeles County is EPA Zone 3 (low risk). California Air Resources Board data shows most LA metro homes testing below 2 pCi/L. Inland areas (Riverside County, San Bernardino foothills) show somewhat higher readings due to granite mountain geology. The EPA recommends all homes be tested regardless of location — radon levels can vary significantly even between neighboring properties.

How much does radon mitigation cost in this area?

In the Los Angeles area, professional radon mitigation (sub-slab depressurization) typically costs $1,000–$2,000 installed (higher CA labor costs). This is a one-time cost that reduces radon by 50–99%. The system requires minimal maintenance and a mitigator can typically complete the work in 3–5 hours.

Should I test if I have a new home?

Absolutely. New homes built with radon-resistant features still show elevated levels in testing — construction conditions and local geology vary too much to assume any home is safe. Test within the first year of occupancy, especially if your home has a basement.

Can I test radon myself, or do I need a professional?

DIY testing is reliable and recommended as a first step. Short-term kits ($12–$25) and long-term kits ($20–$35) are accurate when placed and returned correctly. Professional testing is only required for real estate transactions in some states. If your DIY test shows elevated levels, use a certified professional for both confirmation testing and mitigation.