The EPA Radon Zone Map, Explained
The EPA's Map of Radon Zones assigns every U.S. county to Zone 1 (predicted average indoor screening level above 4 pCi/L), Zone 2 (2 to 4 pCi/L), or Zone 3 (below 2 pCi/L), based on geology, indoor radon measurements, and aerial radioactivity data. It is a planning tool for identifying where testing matters most on average, not a prediction for any specific address.
The zone map's real usefulness is at the policy and awareness level: it is why some municipalities and school districts prioritize radon education and testing programs more than others, and why building codes in Zone 1 counties sometimes require passive radon-resistant construction features in new homes.
For an individual homeowner, the map is a reason to take testing seriously if you are in Zone 1, not a substitute for an actual test result for your specific house.
Common questions
Does living in a Zone 3 county mean testing is unnecessary?
No. The EPA is explicit that any home in any zone can have an elevated result, since radon levels vary house to house based on local soil conditions and the specific structure, not just county-level geology. Zone designation affects how much testing is emphasized in an area, not whether any individual home could test high.
What zone is York County in?
York County is EPA Zone 1. See our page on York County radon levels for the county-specific data and its sourcing.
Have a number you want read?
Tell us the result and your town in York County, or call and read it out. We will tell you what it points to and what a system would involve in a house like yours.
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