Davison County, SD radon potential
EPA's own radon map rates Davison County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. That puts Davison County in the 82nd percentile nationally for radon potential — higher than 82% of the counties EPA has rated.
Where Davison County sits nationally
Davison County, South Dakota is home to about 19,907 people across 435.633 square miles. That works out to roughly 46 people per square mile. Within its own EPA zone, Davison County is bigger by population than 46% of the counties that share it. EPA's geology-based Region 8 groups Davison County with 290 other counties nationally sharing its underlying rock and soil profile.
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 — Davison County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. Being in Zone 1 raises the odds Davison County homes test above the action level, but it does not mean any specific house does — EPA recommends every home be tested, in every zone, because the only way to know is to test.
Testing and mitigation in Davison County
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 Davison County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Davison County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.
Where Davison County's figures come from
Davison County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.