What EPA's radon map says about Westmoreland County
EPA places Westmoreland 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 98th percentile for radon potential — Westmoreland County outranks 98% of every county EPA has rated.
How Westmoreland County compares
About 350,935 people live in Westmoreland County, Pennsylvania, spread over 1,027.713 square miles. Averaged across its land area, Westmoreland County runs about 341 people per square mile. Among counties sharing Westmoreland County's EPA zone, it outranks 94% of them by population. Westmoreland County falls in EPA Radon Region 3, one of 245 counties nationally EPA assigns to that same geologic province.
Why the zone isn't the answer by itself
Where the national indoor average runs about 1.3 pCi/L, Westmoreland County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. That doesn't mean every Westmoreland 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.
Next steps for a home in Westmoreland County
Mitigation cost doesn't depend on Westmoreland 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 Pennsylvania's state radon program
Westmoreland County's test kit answers today; a Airthings radon monitor keeps answering for Westmoreland County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Use code RADONZONE-10OFF at checkout for 10% off.
More on how this number was built
Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.