O'Brien County, IA Radon Zone Data

O'Brien County, IA: EPA's radon zone, explained

EPA places O'Brien 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, O'Brien County ranks higher in radon potential than 78% of rated counties (the 78th percentile).

O'Brien County by the numbers

O'Brien County, Iowa is home to about 14,260 people across 573.035 square miles. That works out to roughly 25 people per square mile. By population, O'Brien County is the 679th largest of every county sharing its EPA zone — the 36th percentile by population within that zone. O'Brien County falls in EPA Radon Region 7, one of 412 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line O'Brien County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. Some O'Brien County homes will test comfortably under the action level despite the county's Zone 1 rating — the only way to know which kind of home you have is an actual test.

If O'Brien County tests above the action level

For a O'Brien 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 O'Brien County, an ongoing number beats a one-time test - a Airthings radon monitor tracks O'Brien 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 O'Brien 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. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.