Yankton County, SD radon potential

EPA places Yankton 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. Rank it against the rest of the country and Yankton County lands in the 83rd percentile for radon potential.

Yankton County by the numbers

Yankton County, South Dakota is home to about 23,509 people across 521.189 square miles. Population density there runs about 45 people per square mile. Within its own EPA zone, Yankton County is bigger by population than 50% of the counties that share it. Yankton County falls in EPA Radon Region 8, one of 291 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 — Yankton County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. A Zone 1 rating means testing is worth doing sooner rather than later, but it is still county-wide average, not a reading for any single house — some homes in Yankton County will test well under the action level, and EPA's guidance is to test regardless of zone.

If Yankton County tests above the action level

A short-term test kit is the standard first step and typically costs far less than mitigation itself. If a test comes back at or above 4 pCi/L, a radon mitigation system for a typical home runs roughly $800–$2,500 (around $1,200 for a common single-family install), driven mainly by foundation type, not by county.

Find South Dakota's state radon program

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

Where Yankton County's figures come from

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