Macomb County, MI: EPA's radon zone, explained

EPA's own radon map rates Macomb County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Macomb County sits at the 32nd percentile nationally for radon potential — above 32 of every 100 rated counties.

Macomb County by the numbers

Macomb County, Michigan is home to about 886,175 people across 479.355 square miles. Population density there runs about 1,849 people per square mile. By population, Macomb County is the 33rd largest of every county sharing its EPA zone — the 97th percentile by population within that zone. Geologically, Macomb County is grouped into EPA Region 5 alongside 523 other counties that share its rock and soil setting.

What this actually means for a house in Macomb County

Macomb County's Zone 3 prediction undercuts the roughly 1.3 pCi/L most US homes average, nowhere near EPA's 4 pCi/L threshold for recommending mitigation. A Zone 3 label describes Macomb County's average, not any one basement or slab in it — testing is still the only way an individual homeowner actually finds out.

If Macomb County tests above the action level

For a Macomb 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 Michigan's state radon program

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

The methodology guide shows exactly which EPA and Census sources feed Macomb County's numbers. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.