Renters and owners in upper-floor apartments often assume that radon is not a concern above the ground floor. Radon forms in the soil and enters buildings from below, so the assumption is that distance from the ground provides protection. That assumption is only partially accurate, and in some building types, upper-floor units have tested at levels well above the EPA action threshold.
According to the CDC, radon is the second leading cause of lung cancer in the United States. Because it is colorless and odorless, the only way to determine your actual exposure level is to test your specific unit.
How Does Radon Work?
Radon gas forms underground as uranium in soil and rock decays. It rises through the ground and enters buildings through:
- Cracks in the foundation
- Gaps around pipes or drains
- Crawl spaces and basements
Once inside, radon accumulates in enclosed spaces with limited ventilation. Basement and ground-floor units carry the highest risk because of their proximity to the source. However, radon does not always remain at ground level.
Can Radon Reach Upper Floors?
Yes. While radon concentration is typically highest at lower levels, several building-level factors allow it to migrate upward:
The Stack Effect
Warm air rises through a building and exits from the top, creating negative pressure at the lower levels. This draws air upward from below, pulling radon from basements and crawl spaces into upper floors. In tightly sealed or energy-efficient buildings, the stack effect is more pronounced.
Shared HVAC Systems
Multi-unit buildings with centralized or interconnected HVAC systems can distribute radon-laden air throughout the building. If lower units or mechanical rooms have elevated radon, the air handling system may carry it to upper floors through shared ductwork.
Plumbing Chases and Utility Corridors
Vertical shafts that carry plumbing, electrical conduit, and elevator equipment create direct pathways for air movement between floors. Radon can travel these pathways without being diluted by fresh air, bypassing horizontal barriers that might otherwise slow its movement.
Is the Risk Lower for Upper Units?
In general, radon levels decline with distance from the soil, so upper-floor units carry lower average risk than basement or ground-floor units. However, lower risk is not the same as no risk.
Several conditions increase the likelihood of radon reaching higher floors:
- Shared ventilation systems that recirculate building air
- Stack effect in sealed or energy-efficient buildings
- Poorly sealed lower units that allow radon to migrate freely
- High radon pressure in the surrounding soil
In the Augusta, GA and CSRA region, buildings on granite-based Piedmont soils can sit above geology with elevated radon potential. Multi-unit buildings in North Augusta, Aiken, and surrounding communities have documented cases of radon reaching upper floors when building-level mitigation was absent.
Should Upstairs Renters Test?
The only reliable way to know the radon level in your specific unit is to test it. The EPA recommends testing all units below the third floor, but acknowledges that upper-floor units can also show elevated levels depending on building construction and ventilation.
Testing is particularly warranted if:
- You live in a multi-unit building with connected HVAC or shared ventilation
- A neighbor on a lower floor has tested high for radon
- Your building is older with limited air sealing
- You or a family member has respiratory concerns
- You are signing a long-term lease in an area with known radon potential
How Often Should You Test?
- Every two years for ongoing monitoring
- After the building installs or modifies any HVAC or radon mitigation system
- Before renewing a long-term lease
- Any time a unit in the building tests at or above 4.0 pCi/L
What Happens If Radon Is Detected in an Upper-Floor Unit?
Radon problems in multi-unit buildings are addressable. Remediation options typically focus at the building level and may include:
- Sealing penetrations and cracks at the building’s foundation
- Installing sub-slab depressurization systems
- Improving HVAC air circulation and fresh air introduction
In Georgia and South Carolina, landlords are generally responsible for addressing documented health hazards in rental units. A certified radon test report from an independent company gives tenants formal documentation to request corrective action. If a landlord declines to respond, tenants may have legal recourse depending on lease terms and local housing codes.
Upper-Floor Does Not Mean Radon-Free
Living above the ground floor reduces, but does not eliminate, radon risk. Building construction, shared mechanical systems, and local geology all affect how radon moves through a structure. The only way to know your actual exposure level is to test the unit you occupy.
Need Radon Testing for Any Floor?
EnviroPro 360 provides certified radon testing for renters, condo owners, and property managers throughout Augusta, the CSRA region, and across Georgia and South Carolina. Whether you are on the ground floor or the fifth, professional testing produces a clear, certified result.
Contact EnviroPro 360 to schedule your test or request a quote.
