What EPA's radon map says about St. James Parish

EPA's own radon map rates St. James Parish zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. That puts St. James Parish in the 13th percentile nationally for radon potential — higher than 13% of the counties EPA has rated.

Where St. James Parish sits nationally

About 19,110 people live in St. James Parish, Louisiana, spread over 237.861 square miles. That works out to roughly 80 people per square mile. Among counties sharing St. James Parish's EPA zone, it outranks 38% of them by population. Geologically, St. James Parish is grouped into EPA Region 6 alongside 502 other counties that share its rock and soil setting.

What this actually means for a house in St. James Parish

St. James Parish's predicted average sits below the national indoor average of about 1.3 pCi/L, well under EPA's 4 pCi/L action level. Don't read Zone 3 as a pass for St. James Parish — EPA's guidance to test every home makes no exception for counties predicted low.

Testing and mitigation in St. James Parish

Mitigation cost doesn't depend on St. James Parish'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 Louisiana's state radon program

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

More on how this number was built

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.