Check Radon Levels by Zip Code
Enter any US zip code to see EPA radon zone data, county risk levels, and local geology information
Enter any US zip code to check radon risk data for your area.
Understanding EPA Radon Zones
The EPA classifies every US county into one of three radon zones
Zone 1 - High Risk
Predicted average indoor screening level greater than 4 pCi/L
Testing strongly recommended for all homes
Zone 2 - Moderate
Predicted average indoor screening level between 2-4 pCi/L
Testing recommended for all homes
Zone 3 - Lower
Predicted average indoor screening level below 2 pCi/L
Testing still recommended
Why Testing Matters Regardless of Zone
Elevated radon has been found in homes in all three EPA zones. Your home's specific radon level depends on many factors including soil composition, foundation type, air pressure differences, and ventilation. Zone classifications indicate general area potential. The only way to know your home's actual radon level is through professional testing.
Common Questions About Radon Risk
The EPA classifies every US county into three radon zones. Zone 1 has high radon potential (greater than 4 pCi/L average), Zone 2 has moderate potential (2-4 pCi/L), and Zone 3 has lower potential (less than 2 pCi/L). However, elevated radon has been found in homes in all zones. Individual testing is essential regardless of your zone.
Learn More About Radon
Why Radon Testing Is Essential
Understanding why every home should be tested, regardless of location or age.
How Radon Mitigation Works
Learn about the science behind radon reduction systems and their effectiveness.
How Often to Test for Radon
EPA guidelines on testing frequency and when to retest your home.
High Radon Risk States
These states have the highest percentage of Zone 1 (high radon potential) counties
Click any state to see its radon risk data
Protect Your Family from Radon
Radon is the second leading cause of lung cancer. Professional testing gives you the information you need to keep your family safe.
Data last verified: January 2026 • Source: EPA-402-R-93-071, EPA Map of Radon Zones