Radon levels in Hawaii

Hawaii is outside the national model's coverage (conterminous US only), so this page shows the EPA radon zone for each county. Zones are a 1993 county-level classification, not a measurement.

Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. How the numbers work.

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EPA Zone 1 counties (0%)

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Zone 2 / Zone 3 counties

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counties predicted ≥ 4 pCi/L

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of ZIP codes predicted ≥ 4 pCi/L

Hawaii counties by predicted radon

Sorted highest to lowest predicted basement average. 5 counties.

CountyPredicted basementUpstairsGradeEPA zoneZIPs
Hawaii Countyn/a-zone onlyEPA Zone 30
Honolulu Countyn/a-zone onlyEPA Zone 30
Kalawao Countyn/a-zone onlyEPA Zone 30
Kauai Countyn/a-zone onlyEPA Zone 30
Maui Countyn/a-zone onlyEPA Zone 30

Hawaii radon questions

Why are there no predicted radon values for Hawaii?
The National Radon Exposure Model covers the conterminous United States only, so Hawaii has no ZIP-level predictions. Each Hawaii county is shown with its EPA radon zone (0 Zone 1, 0 Zone 2, 5 Zone 3). Testing is the only way to know a home's level.

Hawaii radon program

Many states offer free or discounted test kits and keep lists of certified mitigators. Find the Hawaii radon office through the EPA state radon contacts page. Then read how to test and what mitigation costs.