Wood County, WI: EPA's radon zone, explained

Wood County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Nationally that's the 92nd percentile for radon potential — Wood County outranks 92% of every county EPA has rated.

Wood County by the numbers

Wood County, Wisconsin is home to about 73,943 people across 793.028 square miles. That works out to roughly 93 people per square mile. By population, Wood County is the 239th largest of every county sharing its EPA zone — the 78th percentile by population within that zone. EPA's geology-based Region 5 groups Wood County with 523 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Wood County

Where the national indoor average runs about 1.3 pCi/L, Wood County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. A Zone 1 rating means testing is worth doing sooner rather than later, but it is still county-wide average, not a reading for any single house — some homes in Wood County will test well under the action level, and EPA's guidance is to test regardless of zone.

Next steps for a home in Wood County

For a Wood 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 Wisconsin's state radon program

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

Where Wood County's figures come from

Wood 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.