Radon · ZIP 04101
Radon in Portland, ME
ZIP 04101 (Maine) — radon summary sourced from EPA Radon Zones. Refreshed on the cadence of the primary regulator with every claim cited to the source record.
What lands here
Pages show the county zone, what the classification means for home testing recommendations, and state-level supplementary data where available.
Source & refresh
EPA Radon Zones. Refreshed static 1993 baseline plus state-level supplementary updates. Stale data is flagged, never silently served. Primary source →
Limitations specific to this source
Radon is a regional indicator. Address-level radon measurement requires an at-home test kit (often free from state health departments).
Maine context
Radon, lead in older housing, coastal flood
Maine has Zone 1 radon statewide. Older housing stock carries lead-paint + lead-service-line risk in Portland, Lewiston, Bangor. Coastal AE/VE FEMA zones face Risk Rating 2.0 premium increases.
See Maine state page for the full state-level rollup across all 12 dimensions.
Read more on radon
Editorial deep-dives explaining the source data, its limits, and how to read it.
EPA Radon Zones — what 1, 2, and 3 mean and when you should test
EPA classifies every US county into Zone 1 (high), Zone 2 (moderate), or Zone 3 (low) for radon. Plain-English guide to the classifications and at-home testing.
EPA SDWIS — how to read drinking-water violations and what they actually mean
Plain-English guide to EPA SDWIS drinking-water violations: health-based vs. monitoring vs. reporting violations, MCLs, and what triggers a public notice.
Radon and real estate — what disclosure laws and home tests actually require
What home sellers must disclose about radon by state, when home tests are required, and how to interpret radon-mitigation systems if a home you're buying has one.
Radon disclosure during real-estate transactions — state-by-state
Whether sellers must disclose known radon results varies by state. Quick map of mandatory-disclosure states + what to ask for during inspection.
Full dashboard for ZIP 04101
Radon is one of twelve dimensions zipradar federates per address. See the full federated summary for ZIP 04101:
Open Portland, ME dashboard →