St. Francois County, MO Radon Zone Data

St. Francois County, MO: EPA's radon zone, explained

St. Francois County is mapped as Zone 2 - Moderate Potential by EPA — meaning the county-wide average indoor level is predicted between 2 and 4 pCi/L. St. Francois County sits at the 57th percentile nationally for radon potential — above 57 of every 100 rated counties.

Where St. Francois County sits nationally

St. Francois County, Missouri is home to about 67,503 people across 451.886 square miles. That works out to roughly 149 people per square mile. By population, St. Francois County is the 274th largest of every county sharing its EPA zone — the 74th percentile by population within that zone. Geologically, St. Francois 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 St. Francois 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 St. Francois County's Zone 2 prediction. Nothing about a Zone 2 label lowers the case for testing in St. Francois County — EPA recommends it in every zone, moderate included.

Testing and mitigation in St. Francois County

For a St. Francois 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 Missouri's state radon program

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

Where St. Francois County's figures come from

St. Francois 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.