Understanding Radon Levels
Radon levels are measured in picocuries per liter (pCi/L). Here's how to interpret common results:
| Level | Interpretation | Action |
|---|---|---|
| Below 2.0 pCi/L | Low | No action typically needed |
| 2.0 - 3.9 pCi/L | Moderate | Consider mitigation, especially if planning long-term occupancy |
| 4.0 - 7.9 pCi/L | Elevated | EPA recommends mitigation |
| 8.0+ pCi/L | High | Mitigation strongly recommended |
The EPA's action level is 4.0 pCi/L, meaning they recommend fixing homes at or above this level. However, the EPA also notes that no level of radon is completely safe.
What Radon Is
Radon is a naturally occurring radioactive gas that comes from uranium in soil and rock. It seeps into homes through foundation cracks, gaps around pipes, and any opening where the home contacts the ground. Radon is colorless and odorless, so testing is the only way to know if it's present.
Long-term radon exposure is the second leading cause of lung cancer after smoking. The risk increases with exposure level and duration.
Testing Methods
Short-Term Tests
Used during home inspections. The test device sits in the lowest livable level for 48-96 hours under closed-house conditions. Results are available quickly but represent a snapshot in time.
Long-Term Tests
Run for 90+ days and provide a more accurate average. Not practical during a home purchase but useful for homeowners monitoring their property.
Continuous Monitors
Electronic devices that measure radon hourly and detect tampering. Many inspectors now use these during purchase inspections because they provide more data and are harder to manipulate.
If Results Are Elevated
Elevated radon is not a reason to walk away from a home. Radon mitigation is straightforward and effective:
- Mitigation systems cost $800-2,500 depending on home type and complexity
- Systems are 95%+ effective at reducing radon levels
- Installation takes 4-8 hours for most homes
- Operating costs are minimal - the fan uses about as much electricity as a light bulb
Many buyers negotiate for the seller to install a mitigation system or provide a credit for installation costs.
Geographic Factors
Radon levels vary significantly by region. The EPA publishes radon zone maps showing areas with higher potential. However, radon can be elevated in any location - testing is the only way to know.
Homes in Zone 1 (highest potential) areas often include radon mitigation as a standard negotiation item. In lower-potential areas, elevated readings may be less common but still occur.
Negotiating Radon Issues
If radon tests above 4.0 pCi/L, common negotiation approaches include:
- Ask seller to install mitigation system before closing
- Request credit at closing ($1,500-2,500) to cover installation
- Require retest after mitigation to confirm effectiveness
Radon mitigation is a solved problem. Don't let elevated results scare you away from an otherwise good home.