What type of particles are emitted by radon?

• A. Beta particles
• B. Gamma rays
• C. Alpha particles — cause lung cancer when inhaled
• D. Neutrons

Answer: (C)

Radon decays by emitting alpha particles. Alpha particles are heavy, highly ionizing helium nuclei, but they don’t travel far in air. The health concern with radon comes from its decay products in the lungs: when these decay products are inhaled and emit alpha radiation in lung tissue, they cause concentrated DNA damage that raises the risk of lung cancer. Gamma rays and beta particles show up in parts of the decay chain, but the primary type emitted by radon itself is alpha radiation, which is the main reason radon exposure is linked to lung cancer. Neutrons are not produced in this decay process.