Radon decay emits _______ particles, the radiation that presents the greatest hazard to lung tissue.

• A. Beta
• B. Muon
• C. Alpha
• D. Gamma

Answer: (C)

Radon exposure harms mainly from alpha radiation. Alpha particles are heavy and highly ionizing, delivering a large amount of energy over a very short distance. When radon gas is inhaled, its decay products attach to aerosols and lodge in the lungs, so those alpha emissions deposit a high local dose to lung tissue, causing significant cellular damage and increased cancer risk. Beta particles are lighter and more penetrating but cause less damage per unit length, and gamma rays are penetrating with energy spread over a longer path. Muons aren’t produced in radon decay and aren’t the relevant hazard here. Therefore, alpha particles are the radiation emitted that presents the greatest hazard to lung tissue.