Adams County, IN: EPA's radon zone, explained

EPA places Adams County in Zone 1 - Highest Potential — a predicted county-wide average indoor radon level above 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Adams County sits at the 87th percentile nationally for radon potential — above 87 of every 100 rated counties.

How Adams County compares

Adams County, Indiana is home to about 36,584 people across 338.925 square miles. Population density there runs about 108 people per square mile. By population, Adams County is the 411th largest of every county sharing its EPA zone — the 61st percentile by population within that zone. Adams County falls in EPA Radon Region 5, one of 524 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Adams County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. EPA's guidance doesn't change because of a Zone 1 label: test the house. What changes is the reason to not put it off in Adams County specifically.

Next steps for a home in Adams County

For a Adams County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find Indiana's state radon program

For Adams County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Adams County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

Where Adams County's figures come from

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. Whatever zone Adams County carries, the zone explainer covers what it does and doesn't tell you about any one house.