The EPA recommends that radon levels in a home should be below 4.0 picocuries per liter (pCi/L). However, levels under 2.0 pCi/L are considered ideal. If your home’s radon level is 2.0–3.9 pCi/L, mitigation is still encouraged, especially for long-term exposure.
EPA Recommendations for Safe Radon Levels
The U.S. Environmental Protection Agency (EPA) has set 4.0 pCi/L as the action level. This means:
- 4.0 pCi/L or higher: Immediate action is strongly recommended.
- 2.0 to 3.9 pCi/L: Consider mitigation. Long-term exposure may still pose risks.
- Below 2.0 pCi/L: No action typically required, but re-testing every 2 years is wise.
Why Lower Is Better with Radon
Even small amounts of radon carry risk. According to the World Health Organization (WHO), the target level for indoor radon is 1.3 pCi/L, because:
- Radon is radioactive and emits alpha particles.
- Long-term exposure increases your risk of lung cancer.
- Children and smokers are at higher risk of developing radon-related illnesses.
There is no completely safe level of radon, but the lower your exposure, the better your protection.
How to Interpret Your Radon Test Results
| Radon Level | What It Means | Recommended Action |
|---|---|---|
| 4.0 pCi/L or more | Unsafe | Install a mitigation system immediately |
| 2.0–3.9 pCi/L | Borderline | Strongly consider mitigation |
| 0.4–1.9 pCi/L | Acceptable but not risk-free | Re-test in 2 years |
| 0.0–0.3 pCi/L | Low natural background | No action needed |
How to Get Accurate Results
To find out your home’s radon level:
- Use an EPA-approved test kit (short-term or long-term).
- Hire a certified radon measurement professional for reliable results.
- Test every 2 years or after major renovations, HVAC upgrades, or weatherization projects.
Radon levels can vary with season, ventilation, and soil conditions, so it’s best to test during colder months when the home is closed up.
When to Mitigate
If your radon levels are above 2.0 pCi/L, it’s wise to consult a mitigation expert. Most modern systems—such as sub-slab depressurization—can lower levels by 99% or more and operate quietly in the background.