What EPA's radon map says about Lyon County

EPA places Lyon County in Zone 2 - Moderate Potential — a predicted county-wide average indoor radon level between 2 and 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Nationally that's the 51st percentile for radon potential — Lyon County outranks 51% of every county EPA has rated.

How Lyon County compares

About 32,520 people live in Lyon County, Kansas, spread over 847.477 square miles. That works out to roughly 38 people per square mile. Among counties sharing Lyon County's EPA zone, it outranks 55% of them by population. Geologically, Lyon County is grouped into EPA Region 7 alongside 411 other counties that share its rock and soil setting.

What this actually means for a house in Lyon County

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 Lyon County's Zone 2 prediction. Middle-of-the-pack doesn't mean risk-free for any one Lyon County address — a moderate county average still leaves individual homes to test either side of it.

Next steps for a home in Lyon County

Mitigation cost doesn't depend on Lyon 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

Lyon County's test kit answers today; a Airthings radon monitor keeps answering for Lyon 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

Lyon County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.