What EPA's radon map says about Prince William County

Prince William 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 Prince William County in the 64th percentile nationally for radon potential — higher than 64% of the counties EPA has rated.

Where Prince William County sits nationally

About 497,003 people live in Prince William County, Virginia, spread over 335.264 square miles. Population density there runs about 1,482 people per square mile. Among counties sharing Prince William County's EPA zone, it outranks 95% of them by population. EPA's geology-based Region 3 groups Prince William County with 244 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

Neither at the 4 pCi/L action level nor down at the roughly 1.3 pCi/L national indoor norm, Prince William County's Zone 2 prediction lands in the gap between the two. Prince William 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 Prince William County

Mitigation cost doesn't depend on Prince William 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

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

Prince William County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. Whatever zone Prince William County carries, the zone explainer covers what it does and doesn't tell you about any one house.