Short-term kitempowerDX
Standard Radon Test short-term mail-in radon test kit
- Lab fee included
Method: Passive sampler
In home: 48 to 96 hours
Locations and reports
Radon Levels in Honolulu County, Hawaii
EPA puts Honolulu County in Zone 3, its lowest radon zone. Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Ground above low
None
Level with Hawaii
- Honolulu
- 0.0%
- Hawaii
- 0.0%
Share of land USGS rates moderate or high potential
Tests reported
0
None published
A home here needs its own test
EPA radon zone
Zone 3
Lower potential
- 1
- 2
- Zone 3
1 highest, 3 lowest
EPA predicts under 2 pCi/L indoors
Read a result for Honolulu County
Starts at EPA's action level
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.0 pCi/L
At or above 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher.
The data
Honolulu County, At a glance
Honolulu County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
USGS geologic potential: Low across 93% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
No CDC test figures here
CDC has published no radon test figures for Honolulu County. Only a test tells you the level in a home.
Honolulu County, Compared
Honolulu County radon figures, compared
Calculated by Radon411CDC publishes no radon test figure for Honolulu County, and none for any other Hawaii county: its counts over the 2006 to 2015 laboratory totals cover 2,669 counties elsewhere in the country. Across every county in the country with a figure (2,669), 36.3% of reported tests reached that level; no Hawaii county contributes to that pool.
EPA's 1993 map puts Honolulu County in Zone 3, its lowest label: a predicted county average under 2 pCi/L. USGS geology rates 93% of the county's land low radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Honolulu County, Geology
The ground under Honolulu County
PredictedUSGS's geologic map puts all of Honolulu County's mapped land in one class: low radon potential. 93.1% of it lies in the area the map calls Oahu, to which USGS gives a radon index of 5, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Oahu | Primarily alkalic and tholeiitic basalt, colluvium and alluvium derived from basalt, lesser amounts of marine sediments and carbonate rocks | Low | 5 | 93.1% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Honolulu County beside the ground around it
Neither Honolulu County nor Hawaii as a whole has any land USGS rates above low potential.
The map rates the ground, not the air in any home.
Local help
Honolulu County, Local resources
Radon testing and mitigation in Honolulu County
- Hawaii's radon programHawaii's radon program answers questions about testing, mitigation and the rules where you live.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsAsk the program whether it has free or discounted kits, or compare kits you can buy.
- Compare kits
- See the Hawaii directoryNo professionals are listed in Hawaii yet. The state program can point you to registered testers and mitigators.
What it means
Honolulu County, Questions
Questions about radon in Honolulu County
Are radon levels high in Honolulu County?
No CDC testing statistics are published here for Honolulu County, Hawaii yet. No county within 250 miles of Honolulu County has a CDC figure, so the only comparison is the national pool: 36.3% of reported tests at or above 4 pCi/L.
Which counties border Honolulu County?
No county is recorded as sharing a land boundary with Honolulu County.
Products
Honolulu County, Products
Testing a home in Honolulu County
No CDC figure names Honolulu County, and none within 250 miles of it: a test of this home is the only reading it will get. Zone 3 is the lowest label, yet homes at or above 4 pCi/L occur in every zone: a short-term kit (2 to 90 days) is the quick first check in Honolulu County.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL416 long-term radon test kit, lab fee included
- Lab fee included
Method: Alpha track
In home: 90 days to 12 months
Monitor
Corentium Home 2 battery digital radon monitor
- C-NRPP 2024/25: Not included
- Battery
- Bluetooth
- Screen, app
Method: Alpha spectrometry
Readings: Every 60 minutes
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Honolulu County, Bordering counties
Counties bordering Honolulu County
Calculated by Radon411No bordering counties on file
Honolulu County has no county recorded as sharing a land boundary with it. Island and coastal county equivalents legitimately have none.
Honolulu County, Residents
Who lives in Honolulu County
About 988,703 people live in Honolulu County by the Census Bureau's estimate for July 1, 2025, 23,631 fewer than in 2020 (−2.3%). Packed into its land, that is 1,646 people per square mile.
Census lists no incorporated place in Honolulu County: every home in it reads the county's figures.
Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025).
Honolulu County, Homes
Homes in Honolulu County
Honolulu County has 372,329 homes, and many share a building: 36% are in buildings of five or more, 46% are detached houses, against 54% across Hawaii. Half of its homes were built before 1977, close to Hawaii's 1979: 17% date from before 1960 and 18% from 2000 or later. 60% of occupied homes are lived in by their owner (Hawaii: 63%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Honolulu County | Hawaii |
|---|---|---|
| Housing units | 372,329 | 564,905 |
| Detached houses | 46% | 54% |
| In buildings of 5 or more | 36% | 31% |
| Mobile homes | under 1% | under 1% |
| Built before 1960 | 17% | 15% |
| Built since 2000 | 18% | 20% |
| Middle year built | 1977 | 1979 |
| Owner-occupied | 60% | 63% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.