Quick answer: Radon is a naturally occurring radioactive gas that cannot be seen, smelled, or tasted. The U.S. Environmental Protection Agency recommends testing homes for radon regardless of the EPA radon zone because elevated levels have been found in all three zones. The EPA recommends fixing a home at 4 pCi/L or higher and considering action between 2 and 4 pCi/L. A map can describe regional potential; only a test can tell you the radon level in a specific home.
For buyers in Tennessee and Georgia, radon is a good example of why a visual home inspection cannot answer every property question. The house can look clean, dry, and well maintained while radon is elevated because there are no reliable visual clues.
What Is Radon?
Radon forms naturally from the breakdown of uranium in soil and rock. It can move through the ground and enter buildings through openings around foundations, slabs, crawlspaces, utility penetrations, and other pathways.
Because radon is invisible and odorless, testing is the practical way to measure the concentration in indoor air.
What Do EPA Radon Zones Mean?
EPA's Map of Radon Zones groups U.S. counties into three categories based on predicted average indoor screening levels and factors such as geology, indoor measurements, soil, aerial radioactivity, and foundation types.
- Zone 1: highest potential; predicted average indoor radon may be greater than 4 pCi/L.
- Zone 2: moderate potential; predicted average may be between 2 and 4 pCi/L.
- Zone 3: lower potential; predicted average may be below 2 pCi/L.
The critical point is that EPA says the zone map should not be used to decide whether an individual home needs testing. Elevated homes have been found in all zones.
Source: U.S. EPA Map of Radon Zones.
Why Tennessee Buyers Should Not Rely on the County Color Alone
Tennessee contains areas with different radon potential. EPA's supporting material identifies geologic conditions in parts of the state—including the Nashville Basin and Ridge and Valley region—that can contribute to higher radon potential. But even that regional information cannot predict one house accurately.
A home in Chattanooga, Knoxville, or Nashville needs a property-specific test if you want property-specific information.
What About Atlanta and Georgia?
Georgia also contains different radon-potential areas. The same EPA principle applies: county zoning is a resource-planning tool, not a substitute for measuring the home you are buying or living in.
For Atlanta-area buyers, the decision should be simple: if you want to know the radon level, test the property rather than inferring the result from location alone.
How Radon Testing Fits Into a Home Inspection
A standard home inspection evaluates visible and accessible property conditions. Radon requires measurement equipment and a testing protocol, so radon testing is a specialized service.
The testing process should follow the equipment instructions, test protocol, and applicable professional requirements. The result is reported in picocuries per liter (pCi/L).
What Does 4 pCi/L Mean?
EPA recommends that homes be fixed when the radon level is 4 pCi/L or more. EPA also says homeowners should consider fixing when levels are between 2 and 4 pCi/L.
That threshold is an action guideline, not a claim that lower levels have zero risk. If you receive a result near a decision threshold, follow the testing guidance for confirming and responding to the result.
Can a New Home Have Radon?
Yes. Radon is related to the ground, building pathways, and pressure differences—not simply the age of the house. New construction can incorporate radon-resistant features, but EPA still recommends testing after occupancy to know the actual level.
EPA also provides guidance on radon-resistant new construction, particularly in higher-potential areas.
Do Basements Matter?
Radon often enters at the lowest levels of a building, so foundation type and lower-level living space can affect measurement and exposure. However, a slab home is not automatically “safe” and a basement home is not automatically “high.” Testing answers the property-specific question.
Can Radon Be Fixed?
Yes. Radon mitigation systems can reduce indoor radon by collecting soil gas and venting it safely outside. The specific mitigation design depends on the property and should be handled by qualified radon professionals.
If a real estate test is elevated, buyers typically discuss next steps with their agent and appropriate radon professionals within the transaction timeline.
What Can Interfere With a Radon Test?
Test protocols may include closed-building conditions, proper device placement, and avoiding actions that could invalidate the measurement. Follow the instructions provided by the testing professional rather than improvising around the device.
A test result is useful only when the measurement process is credible.
Radon Testing and Real Estate Timing
If radon matters to your decision, schedule it early enough to complete the required measurement period and review the result during your due-diligence window.
Waiting until the end of the inspection period can turn a simple measurement into a deadline problem.
Radon and Other Specialized Services
Radon answers one environmental question. It does not tell you about mold, sewer condition, termites, septic systems, or water quality. Those services require separate evaluation when relevant.
Review My City Home Inspector inspection packages to build the scope around the actual property.
Frequently Asked Questions
Does every home in Tennessee or Georgia need radon testing?
EPA recommends testing all homes regardless of zone. Whether you include a test in a specific real estate transaction is your decision, but the only way to know the home's radon level is to test it.
Can I smell radon?
No. Radon is colorless and odorless.
Is a low-radon county map enough?
No. EPA explicitly says the zone map should not be used to determine whether an individual home needs testing.
What happens if the result is high?
Discuss the result with the testing professional, your real estate professional, and a qualified radon mitigation professional. Follow EPA and applicable state/local guidance for confirmation and mitigation.
Bottom Line
Radon is a measurement problem, not a visual-inspection problem. Regional maps can describe potential, but they cannot tell you the level in a specific house. If you want to know, test.
My City Home Inspector provides radon testing for buyers and homeowners in Chattanooga, Knoxville, Nashville, and Atlanta.
Local Home Inspection Resources
My City Home Inspector serves Chattanooga, Knoxville, Nashville, and Atlanta. Explore your local market page for service-area information and inspection resources.
Featured photo by Alec Krum on Unsplash.
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