Radon gas enters homes without any visible sign. It has no odor, no color, and produces no immediate sensation. The only way to know whether it is present at elevated levels is to test. But understanding how radon moves through soil and into a structure can help homeowners identify where their home is most vulnerable and take more informed action.
Where Radon Comes From
Radon forms from the radioactive decay of uranium, which occurs naturally in soil and rock. As uranium breaks down, it produces radium, which in turn decays into radon gas. This gas moves upward through the soil toward the surface. Because it is a gas, it follows the path of least resistance, which often means entering a nearby structure rather than dispersing into outdoor air.
According to the EPA, radon is found in homes across the United States at varying concentrations. Geology drives this variation. Areas underlain by granite, shale, or phosphate-bearing soils tend to produce more radon than areas with sedimentary clay or sand. Parts of the Piedmont region of Georgia and South Carolina, including the greater Augusta area, sit on formations that produce measurable radon concentrations. Richmond, Columbia, and Aiken counties have all recorded elevated residential radon levels in testing programs.
Common Entry Points
Radon enters homes through any pathway between the soil and the structure’s interior. The most common entry points include:
- Cracks in foundation slabs. Concrete develops micro-cracks as it cures and as the structure settles. Even hairline cracks provide sufficient space for radon gas to migrate from below.
- Foundation wall cracks. Block foundations and poured concrete walls both develop cracks over time. Horizontal or stair-step cracks in block walls are common entry points.
- Sump pits. An open sump pit is a direct connection between the soil below and the interior air. Radon can move freely through water in the pit and into the space above.
- Utility penetrations. Every point where a pipe, conduit, or wire enters the foundation creates a potential gap. These penetrations are rarely perfectly sealed.
- Construction joints. The joint where the foundation wall meets the floor slab is one of the most consistent radon entry points in residential construction. This junction is difficult to seal completely and often develops gaps as the structure moves.
- Crawl space soil. In homes with vented crawl spaces, exposed soil is a continuous radon source. Vapor barriers reduce entry somewhat but do not eliminate it, particularly at seams and edges.
- Floor drains. Drains with broken or dried-out water seals allow soil gas to rise directly into the basement or lower level.
How Radon Moves Through a Home
Once radon enters through the foundation or crawl space, the stack effect governs how it distributes through the structure. Warm air rises and exits through the upper levels of a home, creating a slight negative pressure zone at the lower levels. This negative pressure draws more soil gas inward from below, and it also pulls radon-laden air from the basement or crawl space upward into living areas.
HVAC systems contribute to this process. Return air intakes in lower levels draw air from the basement or first floor into the duct system and distribute it throughout the home. If radon concentrations are elevated in the lower level, the HVAC system can carry those concentrations into upper floors, bedrooms, and areas where occupants spend significant time.
Modern, energy-efficient homes accelerate this process in a specific way. Tighter building envelopes reduce natural air infiltration, which means radon that enters accumulates to higher concentrations because there are fewer opportunities for dilution. The EPA notes that well-sealed homes may have higher radon concentrations than draftier older construction, even when built on the same soil.
Why Testing Is the Only Reliable Answer
Even knowing the common entry points, it is not possible to visually determine whether a home has elevated radon. Entry points may be sealed adequately in one area and not in another. Soil radon concentration varies from one part of a lot to another. A neighbor’s test result tells you nothing definitive about your own home.
According to the CDC, radon exposure is the second leading cause of lung cancer in the United States after smoking. Long-term exposure at elevated levels, even at concentrations that produce no immediate symptoms, increases lung cancer risk significantly. The only way to determine your exposure is through a test.
EnviroPro 360 provides certified radon testing for homeowners throughout Augusta, Evans, Martinez, Grovetown, North Augusta, Aiken, and surrounding communities in Georgia and South Carolina. If your home has never been tested, or if you have made structural changes since your last test, contact us to schedule a test and get a clear picture of what is in your air.
