Where does the greatest health risk from radon exposure typically come from?

The greatest health risk from radon exposure is predominantly linked to alpha particles emitted from its decay products that can attach to lung tissue during inhalation. Radon is a naturally occurring radioactive gas that can accumulate in buildings, particularly in basements and lower levels, when soil gas diffuses into homes.

When radon decays, it produces radioactive progeny, specifically polonium-218 and polonium-214, which can release alpha particles. When these decay products are inhaled, the alpha particles can damage lung tissue and increase the risk of lung cancer. This mechanism of damage is well-documented and is the primary concern regarding radon exposure, making it a significant public health issue, especially in areas where radon levels are elevated.

In contrast, the other options do not represent the main concerns associated with radon exposure. Carbon monoxide is a separate hazard unrelated to radon, dust particles in the air can pose different health risks but are not specifically linked to radon, and high humidity, while it can affect indoor air quality, does not relate to the dangers posed by radon exposure. Thus, the harm from radon is specifically tied to the inhalation of its decay products that emit alpha radiation.