What role does air pressure play regarding radon entry into homes?

Air pressure plays a significant role in the movement of radon gas into homes, particularly as it relates to the principles of pressure differentials. When the air pressure inside a building is lower than the air pressure in the soil surrounding it, a vacuum effect can occur. This difference in pressure creates a situation where radon, which is a naturally occurring radioactive gas found in soil and rock, can be drawn into the home.

This phenomenon is primarily due to what is known as "stack effect" and other factors, such as wind pressure and the use of mechanical ventilation systems. A lower indoor pressure can facilitate the movement of radon through cracks in the foundation, openings around pipes, and other pathways into the living environment. Therefore, lower pressure is indeed a critical factor that can lead to increased radon infiltration, making this choice the most accurate representation of the relationship between air pressure and radon entry into homes.