The short answer
A county radon zone cannot determine the radon level in a home. EPA recommends home testing regardless of zone; use the map as geographic context.
Use the map for the right question
EPA’s map categorizes county radon potential. It can help explain regional context and planning. The result is not a measurement from an individual building and does not certify a home as safe.
Our lookup follows two geographic steps
A ZIP-area search first identifies Census ZCTA-to-county relationships. Those county identifiers are then joined to EPA zone records. The result is a geographic lookup. There is no indoor measurement in that chain.
A decision aid for a homeowner
If your question is about a particular home, use EPA testing guidance and a suitable test. A lower-potential county does not remove the need to test. Follow the test instructions and official interpretation guidance rather than converting a zone into a predicted household result.
How to keep a useful record
Keep the property’s actual test documentation separately from the map result. Record the test dates, location within the building and method from the report. The county zone can provide context, but it should not replace that evidence.
Your next steps
- Regional potential → county zone.
- Indoor concentration → a home test.
- Interpretation and next steps → EPA testing guidance.
- Unknown county match → verify geography, do not guess.
Common questions
Do I need a radon test in a lower-potential zone?
Yes. EPA recommends testing homes regardless of location; the zone map cannot decide whether an individual home needs testing.
Can a ZIP-code radon lookup tell me my home is safe?
No. This lookup joins geographic areas to county zones; it contains no indoor measurement from your home.
Sources and editorial record
Prepared with AI assistance from the linked sources. Independent human review pending. “Public Atlas Editorial” is a publication label. First edition: 2026-09-28. Scheduled source review: 2026-10-28. Data examples update with their source snapshots; the guide text is versioned separately.
Changes to this guide
- 2026-09-28 — First AI-assisted edition published with source links and review status disclosed.
- 2026-09-29 — Added focused reader questions and concise answers with source links; checked primary-source guidance and retained pending human review.