Which mechanism is primarily responsible for radon entry in homes?

Radon entry in homes is primarily driven by pressure differences that create a vacuum effect, drawing radon-laden soil gases into the home. This process occurs because radon is produced from the natural decay of uranium found in soil and rock. As the house creates lower pressure compared to the surrounding soil (especially in basements and lower levels), the radon gas is pulled into the home, where it can accumulate and pose health risks.

This mechanism is particularly significant because it can happen regardless of the home's construction materials or ventilation systems, making it a fundamental aspect of radon entry dynamics. Understanding this process helps in identifying mitigation strategies that can effectively reduce radon levels in homes. Other sources like building materials or outside air are not the main contributors to indoor radon levels compared to the inflow from soil gases, and plumbing systems generally do not serve as a significant pathway for radon intrusion.