Penobscot County, ME Radon Zone Data

Penobscot County, ME radon potential

EPA's own radon map rates Penobscot County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Penobscot County sits at the 96th percentile nationally for radon potential — above 96 of every 100 rated counties.

Where Penobscot County sits nationally

Penobscot County, Maine is home to about 156,840 people across 3,397.185 square miles. Averaged across its land area, Penobscot County runs about 46 people per square mile. Within its own EPA zone, Penobscot County is bigger by population than 88% of the counties that share it. EPA's geology-based Region 1 groups Penobscot County with 58 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Penobscot County

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Penobscot County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. That doesn't mean every Penobscot County house tests high — a zone is a county-wide prediction, never a single-home reading — but it's a reason to test sooner rather than let it wait.

Testing and mitigation in Penobscot 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 Maine's state radon program

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

Where Penobscot County's figures come from

Penobscot County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.