The EPA radon zone map classifies US counties into three risk zones based on predicted average indoor radon levels. Radon is a naturally occurring radioactive gas that can accumulate in homes — it's the second leading cause of lung cancer in the US after smoking. Knowing your zone tells you how urgently to test.
Health note: The EPA recommends testing ALL homes for radon, regardless of zone. Testing takes 2-7 days with a $15-25 kit from any hardware store.
Look Up Your State's Radon Risk
EPA Radon Zone Definitions
Radon Testing and Mitigation Guide
The EPA radon zone lookup provides state-level risk guidance. Radon is a colorless, odorless radioactive gas produced by uranium decay in soil and rock. It enters homes through cracks in foundations, drains, and gaps around pipes. Long-term exposure is the second leading cause of lung cancer — about 21,000 deaths per year in the US.
How to Test for Radon
Short-term kits (charcoal canisters, 2-7 days) are available at hardware stores for $15-25. Place in the lowest livable area, keep windows closed during the test, then mail to a laboratory. Results return in 1-2 weeks. If the result is 4 pCi/L or higher, do a long-term test (90+ days) to confirm before investing in mitigation.
Radon Mitigation Options
Sub-slab depressurization (ASD) is the standard mitigation method — a contractor installs a pipe through the concrete slab and a continuously running fan to exhaust radon below the house to the outside. This typically reduces radon by 50-99% and costs $800-2,500. Sealing cracks alone is insufficient. The EPA recommends hiring a state-certified radon mitigation contractor.
FAQ
Is this radon zone lookup free?
Yes, completely free with no signup required. Find your EPA radon risk zone by state instantly.
What is a safe radon level in a home?
The EPA action level is 4 pCi/L (picocuries per liter) — at this level, mitigation is recommended. The EPA also suggests considering mitigation at 2-4 pCi/L. The average US indoor radon level is about 1.3 pCi/L; outdoor air is about 0.4 pCi/L. There is no completely safe level, but below 2 pCi/L is generally considered acceptable.
What is EPA Radon Zone 1?
EPA Radon Zone 1 counties have a predicted average indoor radon screening level greater than 4 pCi/L (the action level). Zone 1 represents the highest risk and includes large parts of the Midwest, Mountain West, Pennsylvania, and New York.
How do I test my home for radon?
Short-term radon tests (2-7 days using charcoal canisters) are the easiest starting point. They're available at hardware stores for $15-25. Long-term tests (90+ days using alpha track detectors) give more accurate annual average levels. Test in the lowest livable area of your home — basement or first floor.
How much does radon mitigation cost?
Sub-slab depressurization (the most common mitigation method) typically costs $800-2,500 depending on home size and foundation type. It involves installing a pipe through the foundation slab and a fan to exhaust radon from under the home to the outside. This method reduces radon by 50-99%.
Does every Zone 1 state home have high radon?
No. EPA zones indicate average predicted risk at the county level — individual homes vary significantly. A Zone 1 county means testing is strongly recommended, but your specific home could test low or high. Even Zone 3 homes should test at least once, especially before buying or selling.