What EPA's radon map says about St. Lawrence County

St. Lawrence County is mapped as Zone 2 - Moderate Potential by EPA — meaning the county-wide average indoor level is predicted between 2 and 4 pCi/L. Nationally, St. Lawrence County ranks higher in radon potential than 60% of rated counties (the 60th percentile).

St. Lawrence County by the numbers

About 106,198 people live in St. Lawrence County, New York, spread over 2,679.534 square miles. Population density there runs about 40 people per square mile. Among counties sharing St. Lawrence County's EPA zone, it outranks 82% of them by population. EPA's geology-based Region 2 groups St. Lawrence County with 82 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Call it a middle case: above the 1.3 pCi/L most US homes average, below the 4 pCi/L line EPA uses to recommend mitigation — that's St. Lawrence County's Zone 2 prediction. St. Lawrence County's Zone 2 rating sits in the middle nationally; EPA's guidance is unchanged by that — test every home regardless of its zone.

Testing and mitigation in St. Lawrence County

Mitigation cost doesn't depend on St. Lawrence 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

St. Lawrence County's test kit answers today; a Airthings radon monitor keeps answering for St. Lawrence 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

St. Lawrence County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.