Radon · ZIP 97231
Radon in Portland (OR, NW Hills), OR
ZIP 97231 (Oregon) — radon summary sourced from EPA Radon Zones. Refreshed on the cadence of the primary regulator with every claim cited to the source record.
Multnomah County, Oregon
Zone 2 — moderate potential
The EPA Map of Radon Zones classifies Multnomah County as Zone 2 — a predicted average indoor radon screening level between 2 and 4 pCi/L. This is a county-level, 1993-baseline planning classification, not a measurement of any individual address in ZIP 97231.
The Map of Radon Zones should not be used to determine if individual homes need to be tested. No matter where you live, test your home for radon — it's easy and inexpensive.
What lands here
The county-level classification and EPA's own testing guidance for this ZIP's county — shown above.
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).
Oregon context
Wildfire, Cascadia seismic, coastal flood
Oregon has high WUI wildfire risk in the Cascades + eastern + southern forests. Cascadia subduction zone shapes long-term seismic risk. Coastal FEMA VE/AE zones; Portland metro carries some LCRR obligations.
See Oregon 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.
The other dimensions for ZIP 97231
Radon is one of twelve public-records dimensions zipradar indexes per address. See the ZIP 97231 index for the other eleven — each with its own regulator, source and link:
All dimensions for Portland (OR, NW Hills), OR →Frequently asked questions
What is the radon for ZIP 97231?
Multnomah County, Oregon (which covers ZIP 97231) is classified as EPA Radon Zone 2 — a predicted average indoor radon screening level between 2 and 4 pCi/L. This is a county-level, 1993-baseline planning classification, not an address-level measurement. The Map of Radon Zones should not be used to determine if individual homes need to be tested. No matter where you live, test your home for radon — it's easy and inexpensive.
Where does the radon data come from?
EPA Radon Zones (primary regulator). zipradar federates radon on the regulator's published cadence: static 1993 baseline plus state-level supplementary updates. Every claim cites the source record; stale data is flagged, never silently served. The primary source URL: https://www.epa.gov/radon/find-information-about-local-radon-zones-and-state-contact-information.
What are the limitations of radon data?
Radon is a regional indicator. Address-level radon measurement requires an at-home test kit (often free from state health departments).
Is ZIP 97231 (Portland (OR, NW Hills)) data current?
Last verified 2026-09-07. Radon for ZIP 97231 refreshes static 1993 baseline plus state-level supplementary updates per EPA Radon Zones cadence. See the full ZIP dashboard at /zip/97231/ for all 12 dimensions side-by-side.