Atchison County, KS: EPA's radon zone, explained
Atchison County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Rank it against the rest of the country and Atchison County lands in the 80th percentile for radon potential.
Where Atchison County sits nationally
Atchison County, Kansas is home to about 16,249 people across 431.174 square miles. Averaged across its land area, Atchison County runs about 38 people per square mile. By population, Atchison County is the 636th largest of every county sharing its EPA zone — the 40th percentile by population within that zone. Atchison County falls in EPA Radon Region 7, one of 412 counties nationally EPA assigns to that same geologic province.
What this actually means for a house in Atchison County
Atchison County carries a Zone 1 label because its predicted average clears 4 pCi/L outright — three-plus times the 0.4 pCi/L typical outdoors and above the 1.3 pCi/L most homes see. Some Atchison County homes will test comfortably under the action level despite the county's Zone 1 rating — the only way to know which kind of home you have is an actual test.
If Atchison County tests above the action level
For a Atchison County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.
Find Kansas's state radon program
For Atchison County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Atchison County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. Use code RADONZONE-10OFF at checkout for 10% off.
Where Atchison County's figures come from
Atchison 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.