Obtain and correctly scope the EPA Map of Radon Zones as reference data (not a live queryable API)
domain: epa.gov (government) · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Download the national static radon-zone reference layer and county designations from epa.gov/radon/epa-map-radon-zones-and-supplemental-information.
For state-specific PDF maps and technical support documents, use the index at epa.gov/radon/epa-maps-radon-zones-and-supporting-documents-state.
For visualization only, EPA hosts an ArcGIS Online web map embedded at gispub.epa.gov/radon/ — treat it strictly as a viewer, not a documented queryable REST/FeatureServer endpoint.
For actual county-level test-result data referenced alongside the zone map, use the CDC Environmental Health Tracking Network or a state DEP/DOH dataset instead — the zone map itself is not testing data.
Always pair a zone lookup with an actual in-home test — EPA explicitly states the map 'should not be used to determine if individual homes need to be tested.'
Known gotchas
As of this verification there is no live, EPA-maintained public REST/FeatureServer API for the national Map of Radon Zones — only static downloads and an ArcGIS Online viewer exist; do not build automation assuming a queryable federal endpoint.
Don't confuse this national EPA map with state-run radon-zone GIS services (e.g., California Geological Survey's own RadonPotentialZones MapServer) — those are separate state programs with independent methodology.
The underlying map dates to 1993 and has not been comprehensively re-surveyed; treat zone designations as coarse regional context, not current measurements.
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