Montgomery County, IA: EPA's radon zone, explained

EPA places Montgomery 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, Montgomery County ranks higher in radon potential than 76% of rated counties (the 76th percentile).

Where Montgomery County sits nationally

Montgomery County, Iowa is home to about 10,063 people across 424.097 square miles. Population density there runs about 24 people per square mile. By population, Montgomery County is the 758th largest of every county sharing its EPA zone — the 29th percentile by population within that zone. Montgomery County falls in EPA Radon Region 7, one of 412 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Montgomery 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 Montgomery County specifically.

Testing and mitigation in Montgomery County

For a Montgomery 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 Iowa's state radon program

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

Where Montgomery County's figures come from

Montgomery 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.