Is Hand County, SD a radon risk area?

EPA places Hand County in Zone 1 - Highest Potential — a predicted county-wide average indoor radon level above 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. That puts Hand County in the 69th percentile nationally for radon potential — higher than 69% of the counties EPA has rated.

Hand County by the numbers

About 3,097 people live in Hand County, South Dakota, spread over 1,436.633 square miles. Population density there runs about 2 people per square mile. Rank 978 by population within its EPA zone puts Hand County at the 8th percentile among zone peers. EPA's geology-based Region 8 groups Hand 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 — Hand County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. 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 Hand County specifically.

If Hand County tests above the action level

Nothing about Hand 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

Hand County's test kit answers today; a Airthings radon monitor keeps answering for Hand 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. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.