Custer County, SD radon potential

EPA's own radon map rates Custer County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. Nationally, Custer County ranks higher in radon potential than 39% of rated counties (the 39th percentile).

Where Custer County sits nationally

Custer County, South Dakota is home to about 9,330 people across 1,556.943 square miles. Population density there runs about 6 people per square mile. Within its own EPA zone, Custer County is bigger by population than 19% of the counties that share it. EPA's geology-based Region 8 groups Custer County with 290 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Call it a middle case: above the 1.3 pCi/L most US homes average, below the 4 pCi/L line EPA uses to recommend mitigation — that's Custer County's Zone 2 prediction. Middle-of-the-pack doesn't mean risk-free for any one Custer County address — a moderate county average still leaves individual homes to test either side of it.

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

Where Custer County's figures come from

Custer County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.