Hampden County, MA: EPA's radon zone, explained

Hampden 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. Hampden County sits at the 64th percentile nationally for radon potential — above 64 of every 100 rated counties.

Where Hampden County sits nationally

Hampden County, Massachusetts is home to about 464,151 people across 617.006 square miles. Population density there runs about 752 people per square mile. By population, Hampden County is the 55th largest of every county sharing its EPA zone — the 95th percentile by population within that zone. Geologically, Hampden County is grouped into EPA Region 1 alongside 58 other counties that share its rock and soil setting.

What this actually means for a house in Hampden County

Call it a middle case: above the 1.3 pCi/L most US homes average, below the 4 pCi/L line EPA uses to recommend mitigation — that's Hampden County's Zone 2 prediction. A county-wide moderate average, like Hampden County's, can still hide a specific house well above or below it — testing is what actually answers the question.

If Hampden County tests above the action level

For a Hampden County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find Massachusetts's state radon program

For Hampden County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Hampden County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. Use code RADONZONE-10OFF at checkout for 10% off.

Where Hampden County's figures come from

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