Is Holmes County, MS a radon risk area?

Holmes County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. That puts Holmes County in the 11th percentile nationally for radon potential — higher than 11% of the counties EPA has rated.

Where Holmes County sits nationally

About 15,560 people live in Holmes County, Mississippi, spread over 756.674 square miles. Averaged across its land area, Holmes County runs about 21 people per square mile. Rank 702 by population within its EPA zone puts Holmes County at the 32nd percentile among zone peers. EPA's geology-based Region 4 groups Holmes County with 735 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Holmes County

Well clear of both the 1.3 pCi/L national indoor average and EPA's 4 pCi/L action level, Holmes County's Zone 3 prediction is the low end of the scale. Don't read Zone 3 as a pass for Holmes County — EPA's guidance to test every home makes no exception for counties predicted low.

If Holmes County tests above the action level

Nothing about Holmes County'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 Mississippi's state radon program

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

The methodology guide shows exactly which EPA and Census sources feed Holmes County's numbers. Whatever zone Holmes County carries, the zone explainer covers what it does and doesn't tell you about any one house.