What EPA's radon map says about Harper County

EPA's own radon map rates Harper County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. Rank it against the rest of the country and Harper County lands in the 36th percentile for radon potential.

Harper County by the numbers

About 5,413 people live in Harper County, Kansas, spread over 801.274 square miles. That works out to roughly 7 people per square mile. Among counties sharing Harper County's EPA zone, it outranks 10% of them by population. Geologically, Harper County is grouped into EPA Region 7 alongside 411 other counties that share its rock and soil setting.

Zone vs. an actual test

Call it a middle case: above the 1.3 pCi/L most US homes average, below the 4 pCi/L line EPA uses to recommend mitigation — that's Harper County's Zone 2 prediction. Harper County's Zone 2 rating sits in the middle nationally; EPA's guidance is unchanged by that — test every home regardless of its zone.

Testing and mitigation in Harper County

Mitigation cost doesn't depend on Harper County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.

Find Kansas's state radon program

Harper County's test kit answers today; a Airthings radon monitor keeps answering for Harper County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

More on how this number was built

Harper County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. Whatever zone Harper County carries, the zone explainer covers what it does and doesn't tell you about any one house.