Madison County, IA Radon Zone Data

Madison County, IA radon potential

EPA places Madison 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. Rank it against the rest of the country and Madison County lands in the 80th percentile for radon potential.

How Madison County compares

Madison County, Iowa is home to about 17,161 people across 561.006 square miles. Population density there runs about 31 people per square mile. Within its own EPA zone, Madison County is bigger by population than 42% of the counties that share it. EPA's geology-based Region 7 groups Madison County with 411 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Madison County

Madison County carries a Zone 1 label because its predicted average clears 4 pCi/L outright — three-plus times the 0.4 pCi/L typical outdoors and above the 1.3 pCi/L most homes see. 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 Madison County specifically.

Next steps for a home in Madison County

A short-term test kit is the standard first step and typically costs far less than mitigation itself. If a test comes back at or above 4 pCi/L, a radon mitigation system for a typical home runs roughly $800–$2,500 (around $1,200 for a common single-family install), driven mainly by foundation type, not by county.

Find Iowa's state radon program

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

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. Whatever zone Madison County carries, the zone explainer covers what it does and doesn't tell you about any one house.