Alpha radiation is the least dangerous as alpha particles can be stopped by your skin.

Question

Quizplus · Accepted Answer

Alpha radiation is actually the most dangerous because the alpha particles, which are helium nuclei, have a large mass and strong positive charge, meaning they can cause significant damage to living tissue. However, this danger only exists for external exposure. Alpha particles cannot penetrate the dead outer layer of skin and are thus stopped by it. However, if alpha-emitting materials are ingested or inhaled, they can be extremely hazardous to health.

Alpha Radiation Is the Least Dangerous as Alpha Particles Can