Is Jefferson Parish, LA a radon risk area?

Jefferson Parish is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Nationally that's the 31st percentile for radon potential — Jefferson Parish outranks 31% of every county EPA has rated.

Jefferson Parish by the numbers

About 427,253 people live in Jefferson Parish, Louisiana, spread over 300.864 square miles. That works out to roughly 1,420 people per square mile. Rank 63 by population within its EPA zone puts Jefferson Parish at the 94th percentile among zone peers. EPA's geology-based Region 6 groups Jefferson Parish with 502 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Jefferson Parish

A Zone 3 county like Jefferson Parish is predicted closer to the 0.4 pCi/L typical outdoors than to EPA's 4 pCi/L action level. Don't read Zone 3 as a pass for Jefferson Parish — EPA's guidance to test every home makes no exception for counties predicted low.

If Jefferson Parish tests above the action level

Nothing about Jefferson Parish's EPA zone changes the mitigation number: $800–$2,500 nationally (around $1,200 typical), set by the house's foundation rather than the county it sits in — and only relevant once a test actually clears 4 pCi/L.

Find Louisiana's state radon program

Jefferson Parish's test kit answers today; a Airthings radon monitor keeps answering for Jefferson 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

Jefferson 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.