What is the primary factor that draws radon into a home from the surrounding soil?

The primary factor that draws radon into a home from the surrounding soil is air pressure. This phenomenon is largely governed by the principle of pressure differentials between the soil and the air inside a house. When the air pressure inside a home is lower than the pressure in the soil or rock surrounding the foundation, radon gas, which is naturally present in the soil as a decay product of uranium, can be pulled into the home.

This difference in air pressure can occur due to various factors, such as changes in temperature, wind dynamics, and the building's air ventilation systems. Homes with poor ventilation or those that are tightly sealed can experience greater negative pressure, exacerbating the influx of radon. Thus, understanding the role of air pressure is crucial in radon mitigation efforts and home construction practices to minimize radon exposure in indoor environments.