What EPA's radon map says about Seneca County

EPA places Seneca 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 that's the 86th percentile for radon potential — Seneca County outranks 86% of every county EPA has rated.

Where Seneca County sits nationally

About 32,650 people live in Seneca County, New York, spread over 323.699 square miles. Population density there runs about 101 people per square mile. Among counties sharing Seneca County's EPA zone, it outranks 58% of them by population. EPA's geology-based Region 2 groups Seneca County with 82 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

Where the national indoor average runs about 1.3 pCi/L, Seneca County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. Being in Zone 1 raises the odds Seneca County homes test above the action level, but it does not mean any specific house does — EPA recommends every home be tested, in every zone, because the only way to know is to test.

Testing and mitigation in Seneca County

Mitigation cost doesn't depend on Seneca 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

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

More on how this number was built

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