Brown County, OH: EPA's radon zone, explained

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 54th percentile for radon potential.

Where Brown County sits nationally

Brown County, Ohio is home to about 44,292 people across 489.551 square miles. Averaged across its land area, Brown County runs about 90 people per square mile. By population, Brown County is the 370th largest of every county sharing its EPA zone — the 64th percentile by population within that zone. Brown County falls in EPA Radon Region 5, one of 524 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Brown County's Zone 2 prediction clears the 1.3 pCi/L national indoor average without reaching EPA's own 4 pCi/L point for recommending a fix. 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

For a Brown 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 Ohio's state radon program

For Brown County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Brown County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. Code RADONZONE-10OFF takes 10% off at checkout.

Where Brown County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Brown County's numbers. Whatever zone Brown County carries, the zone explainer covers what it does and doesn't tell you about any one house.