Delaware County, IA radon potential

EPA's own radon map rates Delaware County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Nationally that's the 81st percentile for radon potential — Delaware County outranks 81% of every county EPA has rated.

How Delaware County compares

Delaware County, Iowa is home to about 17,609 people across 577.685 square miles. Averaged across its land area, Delaware County runs about 30 people per square mile. Within its own EPA zone, Delaware County is bigger by population than 43% of the counties that share it. Delaware County falls in EPA Radon Region 7, one of 412 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Where the national indoor average runs about 1.3 pCi/L, Delaware County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. A Zone 1 rating means testing is worth doing sooner rather than later, but it is still county-wide average, not a reading for any single house — some homes in Delaware County will test well under the action level, and EPA's guidance is to test regardless of zone.

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

Where Delaware County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Delaware County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.