What is the most common factor that drives radon into homes?

The most common factor that drives radon into homes is the air pressure difference between indoor air and soil gas. Radon is a naturally occurring radioactive gas that is produced from the decay of uranium found in soil and rock. It can seep into buildings through cracks in floors, walls, and foundations, as well as through construction joints and gaps in service lines.

When the air pressure inside a home is lower than that in the soil surrounding the foundation, the differential pressure allows radon gas to be drawn into the building. This is often exacerbated by the house's ventilation system, which can create negative pressure. Homes that are well-sealed or those that have poor ventilation are particularly susceptible, as these conditions increase the likelihood of lower indoor pressure compared to the soil gas outside.

Understanding this mechanism is key to effectively assessing radon risk and implementing mitigation strategies as needed. While humidity levels, temperature fluctuations, and types of building materials may influence indoor air quality or contribute to the radon dynamics in a building, they are not the primary drivers for radon ingress. The fundamental principle rests on the air pressure differential, making it the most critical factor in the movement of radon into homes.