Radon in Murfreesboro and Rutherford County

Radon in Murfreesboro comes down to geology, housing, and the public data available. Here's what the EPA, Tennessee's radon program, and USGS say about Rutherford County, with links to each source.

EPA zone: Zone 1

The EPA's county-level radon zone data lists Rutherford County, Tennessee as Zone 1, the highest-potential category, with a predicted average indoor screening level above 4 pCi/L. Its neighbors Davidson, Williamson, and Wilson counties are also Zone 1.

The EPA notes that the 1993 map was built from indoor measurements, geology, aerial radioactivity, soils, and foundation types. It is meant to help target programs and codes, not to decide whether an individual house needs testing. Homes with high radon turn up in every zone, so every home should be tested.

What Tennessee's radon program reports

The Tennessee Radon Program, run by TDEC:

• Says that because of Tennessee's unique geology, dangerous radon levels are common in homes.
• Reports that about 1 in 4 homes that request a free state test kit test above 4 pCi/L.
• Distributes about 6,000 free test kits a year, one per household, with lab analysis included.
• Offers training for radon measurement and mitigation professionals through Kansas State University.

County-level test data

Published county-level test counts for Rutherford County are thin. One compilation we reviewed showed only a few dozen tests, too few to quote a reliable county average. So we lean on the EPA zone and TDEC's statewide findings rather than a local percentage. Your own test is what counts.

The geology: limestone of the Central Basin

Murfreesboro sits near the center of Tennessee's Central Basin, a broad lowland where erosion has stripped away younger rock to expose Ordovician limestones. One of these units, the Stones River Group, takes its name from the Stones River that flows past the city.

The U.S. Geological Survey's geologic radon assessment for EPA Region 4, which covers Tennessee, links radon potential to rock type and the soils formed on it. Carbonate rocks like limestone can produce clay-rich residual soils in which uranium and its decay products are concentrated, and the fractures, solution channels, and sinkholes of karst terrain give soil gas easy paths to move. That combination is a big reason so much of Middle Tennessee is Zone 1.

The cedar glades around Murfreesboro, with their thin soils over flat limestone, are a visible reminder of how close the bedrock is to the surface in parts of the county. In other places deep red clay covers the rock. Both conditions affect how radon moves, which is part of why homes on the same street can test differently.

Housing patterns that matter

• Crawl spaces are very common in Rutherford County housing, older and newer. They expose soil directly under the floor. See crawl space mitigation.
• Slab-on-grade construction is common in newer subdivisions and garages.
• Basements are less common than in some regions but do exist, especially on sloped lots.
• New construction is booming, so radon-resistant building features are worth asking about. See new construction.

Licensing in Tennessee

Tennessee does not license radon mitigation contractors. Choose a professional certified through the National Radon Proficiency Program (NRPP) or the National Radon Safety Board (NRSB), and verify the listing.

Next steps

1. Order the free TDEC kit or book a professional test. See testing.
2. If you're at or above 4 pCi/L, talk to a certified mitigator. See mitigation.

Where this information comes from

• EPA Map of Radon Zones, county data (Rutherford County, TN: Zone 1)
• Tennessee Department of Environment and Conservation: Tennessee Radon Program
• Tennessee Radon Program free test kit request (TDEC)
• USGS Open-File Report 93-292-D, Geologic Radon Potential of EPA Region 4 (includes Tennessee)
• EPA: Health Risk of Radon
• EPA: Radon Frequently Asked Questions