Is Todd County, SD a radon risk area?

Todd County is mapped as Zone 2 - Moderate Potential by EPA — meaning the county-wide average indoor level is predicted between 2 and 4 pCi/L. Nationally, Todd County ranks higher in radon potential than 39% of rated counties (the 39th percentile).

How Todd County compares

About 9,172 people live in Todd County, South Dakota, spread over 1,388.593 square miles. That works out to roughly 7 people per square mile. Rank 835 by population within its EPA zone puts Todd County at the 19th percentile among zone peers. EPA's geology-based Region 8 groups Todd County with 290 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

EPA's Zone 2 rating for Todd County sits below its own 4 pCi/L action level but above the national indoor average of about 1.3 pCi/L. Todd County's Zone 2 rating sits in the middle nationally; EPA's guidance is unchanged by that — test every home regardless of its zone.

Next steps for a home in Todd County

Nothing about Todd County's EPA zone changes the mitigation number: $800–$2,500 nationally (around $1,200 typical), set by the house's foundation rather than the county it sits in — and only relevant once a test actually clears 4 pCi/L.

Find South Dakota's state radon program

Todd County's test kit answers today; a Airthings radon monitor keeps answering for Todd 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

Todd 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.