What EPA's radon map says about Roberts County

Roberts County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Nationally, Roberts County ranks higher in radon potential than 76% of rated counties (the 76th percentile).

Roberts County by the numbers

About 10,283 people live in Roberts County, South Dakota, spread over 1,101.055 square miles. Population density there runs about 9 people per square mile. Among counties sharing Roberts County's EPA zone, it outranks 29% of them by population. Roberts 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 Roberts County

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Roberts County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. That doesn't mean every Roberts 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.

Testing and mitigation in Roberts County

Mitigation cost doesn't depend on Roberts County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.

Find South Dakota's state radon program

Roberts County's test kit answers today; a Airthings radon monitor keeps answering for Roberts County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Code RADONZONE-10OFF takes 10% off at checkout.

More on how this number was built

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