How testing works
- Short-term tests run 2 to 90 days; real-estate tests are usually 2 to 7 days with a continuous monitor.
- Long-term tests run more than 90 days and give a better annual average.
- Tests are placed in the lowest lived-in level, away from drafts, kitchens and bathrooms.
Action levels
| Result | Recommendation |
|---|---|
| 4.0 pCi/L or higher | EPA recommends mitigation |
| 2.0 to 4.0 pCi/L | EPA suggests considering mitigation |
| Below 2.0 pCi/L | No action generally recommended |
Mitigation
The most common system is sub-slab depressurization: a pipe through the slab with a fan that draws soil gas from under the house and vents it above the roof. In crawlspace homes, a sealed vapor barrier with a fan does a similar job. Sealing cracks alone rarely solves high readings.
Common questions
Is radon common in Southern California?
Average levels in most of coastal Southern California are lower than in many other parts of the country, but elevated readings do occur, including in some foothill and inland areas. The California Department of Public Health publishes test data by ZIP code.
Can I test during escrow?
Yes. A short-term test can be completed within a typical contingency period. The house should be kept closed, except for normal entry, for 12 hours before and during the test.