Morton County, ND: EPA's radon zone, explained

EPA places Morton County in Zone 1 - Highest Potential — a predicted county-wide average indoor radon level above 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Nationally, Morton County ranks higher in radon potential than 86% of rated counties (the 86th percentile).

How Morton County compares

Morton County, North Dakota is home to about 34,194 people across 1,925.888 square miles. That works out to roughly 18 people per square mile. By population, Morton County is the 429th largest of every county sharing its EPA zone — the 60th percentile by population within that zone. EPA's geology-based Region 8 groups Morton County with 290 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Morton County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. That doesn't mean every Morton County house tests high — a zone is a county-wide prediction, never a single-home reading — but it's a reason to test sooner rather than let it wait.

If Morton County tests above the action level

For a Morton 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 North Dakota's state radon program

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

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