What EPA's radon map says about Westchester County

EPA's own radon map rates Westchester County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Westchester County sits at the 32nd percentile nationally for radon potential — above 32 of every 100 rated counties.

Westchester County by the numbers

About 1,006,447 people live in Westchester County, New York, spread over 430.817 square miles. Population density there runs about 2,336 people per square mile. Among counties sharing Westchester County's EPA zone, it outranks 98% of them by population. EPA's geology-based Region 2 groups Westchester County with 82 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

A Zone 3 county like Westchester County is predicted closer to the 0.4 pCi/L typical outdoors than to EPA's 4 pCi/L action level. Low doesn't mean zero: EPA's own data shows homes in Zone 3 counties like Westchester County testing above the action level often enough that skipping a test isn't the safe assumption.

Next steps for a home in Westchester County

Mitigation cost doesn't depend on Westchester 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

Westchester County's test kit answers today; a Airthings radon monitor keeps answering for Westchester 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

The methodology guide shows exactly which EPA and Census sources feed Westchester County's numbers. Whatever zone Westchester County carries, the zone explainer covers what it does and doesn't tell you about any one house.