What EPA's radon map says about Cortland County

EPA places Cortland 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. That puts Cortland County in the 89th percentile nationally for radon potential — higher than 89% of the counties EPA has rated.

How Cortland County compares

About 45,945 people live in Cortland County, New York, spread over 498.774 square miles. Population density there runs about 92 people per square mile. Among counties sharing Cortland County's EPA zone, it outranks 68% of them by population. Cortland County falls in EPA Radon Region 2, one of 83 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

Cortland 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. That doesn't mean every Cortland County house tests high — a zone is a county-wide prediction, never a single-home reading — but it's a reason to test sooner rather than let it wait.

If Cortland County tests above the action level

Mitigation cost doesn't depend on Cortland County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.

Find New York's state radon program

Cortland County's test kit answers today; a Airthings radon monitor keeps answering for Cortland County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

More on how this number was built

Cortland 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.