Kingsbury County, SD: EPA's radon zone, explained

EPA's own radon map rates Kingsbury County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. That puts Kingsbury County in the 71st percentile nationally for radon potential — higher than 71% of the counties EPA has rated.

How Kingsbury County compares

Kingsbury County, South Dakota is home to about 5,261 people across 832.237 square miles. That works out to roughly 6 people per square mile. By population, Kingsbury County is the 916th largest of every county sharing its EPA zone — the 14th percentile by population within that zone. Kingsbury County falls in EPA Radon Region 8, one of 291 counties nationally EPA assigns to that same geologic province.

What this actually means for a house in Kingsbury County

Kingsbury County carries a Zone 1 label because its predicted average clears 4 pCi/L outright — three-plus times the 0.4 pCi/L typical outdoors and above the 1.3 pCi/L most homes see. That doesn't mean every Kingsbury County house tests high — a zone is a county-wide prediction, never a single-home reading — but it's a reason to test sooner rather than let it wait.

If Kingsbury County tests above the action level

For a Kingsbury 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 South Dakota's state radon program

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

Where Kingsbury County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Kingsbury County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.