Homeowner radon guide
Radon Levels Explained
Radon in air is commonly reported in picocuries per liter, or pCi/L. A result measures a period of time; it is not a permanent label for a house.
Below 2 pCi/L
This is below EPA's consider-action range but not completely risk-free. Consider periodic retesting, especially after major building changes.
2 to below 4 pCi/L
EPA suggests considering radon reduction. A longer-term test may help characterize average conditions when time permits.
4 pCi/L or higher
EPA recommends taking action to reduce radon. Follow appropriate confirmation guidance and evaluate mitigation.
Why results move
Weather, pressure, heating and cooling, foundation conditions, ventilation, and season can affect a measurement.
What to do next
Use the cost estimator for planning or search for professionals whose recorded service area matches your ZIP code.
Content reviewed 2026-08-20. Educational information only; testing and a property-specific assessment are still required.