What EPA's radon map says about Smyth County

EPA's own radon map rates Smyth County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. That puts Smyth County in the 85th percentile nationally for radon potential — higher than 85% of the counties EPA has rated.

Where Smyth County sits nationally

About 29,137 people live in Smyth County, Virginia, spread over 451.439 square miles. That works out to roughly 65 people per square mile. Among counties sharing Smyth County's EPA zone, it outranks 55% of them by population. Smyth County falls in EPA Radon Region 3, one of 245 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Smyth County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. Being in Zone 1 raises the odds Smyth 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.

Next steps for a home in Smyth County

Mitigation cost doesn't depend on Smyth 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 Virginia's state radon program

Smyth County's test kit answers today; a Airthings radon monitor keeps answering for Smyth 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 Smyth County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.