Describe the physical pathway by which radon gas typically enters an indoor environment from the ground.

Radon gas originates from the natural radioactive decay of uranium, which is commonly found in soil and rock formations beneath and around buildings. This continuous process releases radon, an invisible, odorless, and tasteless gas, into the surrounding ground. As a gas, radon can move through the tiny interconnected spaces, or pores, within the soil and rock. This movement occurs primarily through two mechanisms: diffusion and pressure-driven flow. Diffusion is the natural tendency of gas molecules to spread out from an area of higher concentration to an area of lower concentration. However, the most significant mechanism for radon entry into indoor environments is pressure-driven flow, also known as convection, which is essentially the movement of gas due to differences in air p....