Jefferson County, NY: EPA's radon zone, explained
Jefferson 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. That puts Jefferson County in the 60th percentile nationally for radon potential — higher than 60% of the counties EPA has rated.
Where Jefferson County sits nationally
Jefferson County, New York is home to about 113,140 people across 1,267.932 square miles. Averaged across its land area, Jefferson County runs about 89 people per square mile. By population, Jefferson County is the 178th largest of every county sharing its EPA zone — the 83rd percentile by population within that zone. Geologically, Jefferson County is grouped into EPA Region 2 alongside 82 other counties that share its rock and soil setting.
Why the zone isn't the answer by itself
Jefferson County's predicted average falls between EPA's 4 pCi/L action level and the national indoor average of about 1.3 pCi/L (outdoor air runs roughly 0.4 pCi/L). Middle-of-the-pack doesn't mean risk-free for any one Jefferson County address — a moderate county average still leaves individual homes to test either side of it.
Testing and mitigation in Jefferson County
For a Jefferson 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 New York's state radon program
For Jefferson County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Jefferson County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. Use code RADONZONE-10OFF at checkout for 10% off.
Where Jefferson 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.