Pennington County, MN: EPA's radon zone, explained

Pennington County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Nationally, Pennington County ranks higher in radon potential than 78% of rated counties (the 78th percentile).

Pennington County by the numbers

Pennington County, Minnesota is home to about 13,652 people across 616.52 square miles. Averaged across its land area, Pennington County runs about 22 people per square mile. By population, Pennington County is the 694th largest of every county sharing its EPA zone — the 35th percentile by population within that zone. Pennington County falls in EPA Radon Region 5, one of 524 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

Pennington County's predicted average sits above EPA's own action level of 4 pCi/L — the concentration at which EPA recommends fixing a home — versus a national average around 1.3 pCi/L indoors and 0.4 pCi/L outdoors. EPA's guidance doesn't change because of a Zone 1 label: test the house. What changes is the reason to not put it off in Pennington County specifically.

If Pennington County tests above the action level

For a Pennington 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 Minnesota's state radon program

For Pennington County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Pennington 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 Pennington County's figures come from

Pennington 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.