Kalawao County, HI: EPA's radon zone, explained

EPA's own radon map rates Kalawao County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Rank it against the rest of the country and Kalawao County lands in the 0th percentile for radon potential.

How Kalawao County compares

Kalawao County, Hawaii is home to about 81 people across 11.991 square miles. Averaged across its land area, Kalawao County runs about 7 people per square mile. By population, Kalawao County is the 1030th largest of every county sharing its EPA zone — the 0th percentile by population within that zone. EPA's geology-based Region 9 groups Kalawao County with 94 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Kalawao County

Well clear of both the 1.3 pCi/L national indoor average and EPA's 4 pCi/L action level, Kalawao County's Zone 3 prediction is the low end of the scale. A Zone 3 label describes Kalawao County's average, not any one basement or slab in it — testing is still the only way an individual homeowner actually finds out.

Testing and mitigation in Kalawao County

For a Kalawao County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find Hawaii's state radon program

For Kalawao County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Kalawao County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

Where Kalawao County's figures come from

Kalawao County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.