What EPA's radon map says about Buffalo County

EPA's own radon map rates Buffalo County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Nationally, Buffalo County ranks higher in radon potential than 67% of rated counties (the 67th percentile).

Buffalo County by the numbers

About 1,825 people live in Buffalo County, South Dakota, spread over 471.405 square miles. Averaged across its land area, Buffalo County runs about 4 people per square mile. Among counties sharing Buffalo County's EPA zone, it outranks 3% of them by population. Geologically, Buffalo County is grouped into EPA Region 8 alongside 290 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

Where the national indoor average runs about 1.3 pCi/L, Buffalo County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. EPA's guidance doesn't change because of a Zone 1 label: test the house. What changes is the reason to not put it off in Buffalo County specifically.

If Buffalo County tests above the action level

Mitigation cost doesn't depend on Buffalo 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

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

More on how this number was built

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