Which construction feature is known to be a significant entry pathway for radon?

Foundation openings are recognized as a significant entry pathway for radon because they provide direct access from the ground into a building. Radon is a naturally occurring radioactive gas released from the decay of uranium found in soil and rock, and it can seep through cracks and gaps in the foundation of a structure. This includes openings around pipes, wires, or where the foundation meets the walls.

Understanding the pathways through which radon can enter a building is crucial for effective radon mitigation. While other construction features mentioned, such as basement flooring and wall cavities, can affect radon levels, they typically serve more as pathways for accumulation rather than direct entry points. Roof ventilation systems are generally situated far from the ground, making them less likely to contribute to radon infiltration. Hence, focusing on foundation openings is essential for assessing and addressing radon risks in residential and commercial buildings.