St. John the Baptist Parish, LA radon potential

EPA places St. John the Baptist Parish in Zone 3 - Low Potential — a predicted county-wide average indoor radon level below 2 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. That puts St. John the Baptist Parish in the 20th percentile nationally for radon potential — higher than 20% of the counties EPA has rated.

Where St. John the Baptist Parish sits nationally

St. John the Baptist Parish, Louisiana is home to about 39,694 people across 214.474 square miles. That works out to roughly 185 people per square mile. Within its own EPA zone, St. John the Baptist Parish is bigger by population than 61% of the counties that share it. EPA's geology-based Region 6 groups St. John the Baptist Parish with 502 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

St. John the Baptist 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. Even at Zone 3, St. John the Baptist Parish homes are not guaranteed a low reading — zone is a county-wide average, and EPA recommends testing every home regardless of zone.

Testing and mitigation in St. John the Baptist Parish

A short-term test kit is the standard first step and typically costs far less than mitigation itself. If a test comes back at or above 4 pCi/L, a radon mitigation system for a typical home runs roughly $800–$2,500 (around $1,200 for a common single-family install), driven mainly by foundation type, not by county.

Find Louisiana's state radon program

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

Where St. John the Baptist Parish's figures come from

St. John the Baptist Parish'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.