How Radon Enters Your Home
Radon gas enters the home through the slab, basement, or crawl space. Pressure differences within the home (from warm air rising and other natural effects) pull radon into living spaces from the soil. Furnace & air conditioning systems can distribute the air through the structure.
While sealing may be a necessary part of the radon mitigation process, the EPA does not recommend the use of sealing alone to reduce radon because by itself, sealing has not been shown to lower radon levels significantly or consistently.
Any home may have a radon problem, new or old with or without a basement, sealed basement or not.
Radon from soil gas is the main cause of radon problems. Other less common sources include well water and building materials. Measuring radon concentration in the air is recommended for initial testing.