Is McHenry County, ND a radon risk area?

EPA's own radon map rates McHenry County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Nationally, McHenry County ranks higher in radon potential than 71% of rated counties (the 71st percentile).

How McHenry County compares

About 5,135 people live in McHenry County, North Dakota, spread over 1,873.942 square miles. Averaged across its land area, McHenry County runs about 3 people per square mile. Rank 922 by population within its EPA zone puts McHenry County at the 13th percentile among zone peers. Geologically, McHenry County is grouped into EPA Region 8 alongside 290 other counties that share its rock and soil setting.

What this actually means for a house in McHenry County

McHenry 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. That doesn't mean every McHenry 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.

Testing and mitigation in McHenry County

Nothing about McHenry 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 North Dakota's state radon program

McHenry County's test kit answers today; a Airthings radon monitor keeps answering for McHenry County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

More on how this number was built

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.