Bristol County, MA radon potential

EPA's own radon map rates Bristol County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. That puts Bristol County in the 65th percentile nationally for radon potential — higher than 65% of the counties EPA has rated.

Where Bristol County sits nationally

Bristol County, Massachusetts is home to about 588,593 people across 553.118 square miles. That works out to roughly 1,064 people per square mile. Within its own EPA zone, Bristol County is bigger by population than 96% of the counties that share it. Bristol County falls in EPA Radon Region 1, one of 59 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

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 Bristol County's Zone 2 prediction. Bristol 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 Bristol County

A short-term test kit is the standard first step and typically costs far less than mitigation itself. If a test comes back at or above 4 pCi/L, a radon mitigation system for a typical home runs roughly $800–$2,500 (around $1,200 for a common single-family install), driven mainly by foundation type, not by county.

Find Massachusetts's state radon program

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

Where Bristol County's figures come from

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.