What EPA's radon map says about Brown County

Brown 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 Brown County lands in the 75th percentile for radon potential.

Where Brown County sits nationally

About 9,142 people live in Brown County, Kansas, spread over 570.871 square miles. Population density there runs about 16 people per square mile. Among counties sharing Brown County's EPA zone, it outranks 26% of them by population. Brown County falls in EPA Radon Region 7, one of 412 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

Brown 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. Being in Zone 1 raises the odds Brown County homes test above the action level, but it does not mean any specific house does — EPA recommends every home be tested, in every zone, because the only way to know is to test.

Testing and mitigation in Brown County

Mitigation cost doesn't depend on Brown 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 Kansas's state radon program

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

Brown County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.