Is Brown County, WI a radon risk area?

EPA's own radon map rates Brown County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. Rank it against the rest of the country and Brown County lands in the 63rd percentile for radon potential.

Brown County by the numbers

About 273,909 people live in Brown County, Wisconsin, spread over 530.096 square miles. Averaged across its land area, Brown County runs about 517 people per square mile. Rank 87 by population within its EPA zone puts Brown County at the 92nd percentile among zone peers. EPA's geology-based Region 5 groups Brown County with 523 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Brown County

Brown County's predicted average falls between EPA's 4 pCi/L action level and the national indoor average of about 1.3 pCi/L (outdoor air runs roughly 0.4 pCi/L). Middle-of-the-pack doesn't mean risk-free for any one Brown County address — a moderate county average still leaves individual homes to test either side of it.

If Brown County tests above the action level

Nothing about Brown 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 Wisconsin'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. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.