What EPA's radon map says about Worcester County

Worcester County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Rank it against the rest of the country and Worcester County lands in the 100th percentile for radon potential.

Worcester County by the numbers

About 881,248 people live in Worcester County, Massachusetts, spread over 1,510.67 square miles. That works out to roughly 583 people per square mile. Among counties sharing Worcester County's EPA zone, it outranks 99% of them by population. Worcester County falls in EPA Radon Region 1, one of 59 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

Worcester County carries a Zone 1 label because its predicted average clears 4 pCi/L outright — three-plus times the 0.4 pCi/L typical outdoors and above the 1.3 pCi/L most homes see. EPA's guidance doesn't change because of a Zone 1 label: test the house. What changes is the reason to not put it off in Worcester County specifically.

Next steps for a home in Worcester County

Mitigation cost doesn't depend on Worcester 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 Massachusetts's state radon program

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

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.