Which type of hazard does not penetrate the skin but can cause long-term damage if inhaled?

Alpha radiation is characterized by its inability to penetrate the skin due to its relatively large mass and charge. Alpha particles can be effectively blocked by just a sheet of paper or the outer layer of human skin. However, if alpha-emitting materials are inhaled or ingested, they can become a significant health risk. Inside the body, alpha particles can cause substantial damage to tissues and organs because they release their energy over a very short distance, leading to high levels of localized radiation exposure. This can result in long-term health issues, including cancer, as the damage accumulates over time.

In contrast, beta radiation can penetrate the skin to some degree and may also pose inhalation risks, while gamma radiation can penetrate through the body but generally does not have the same localized damage risk associated with alpha particles. Thermal hazards involve heat exposure and do not relate to radiation, making them an unrelated factor in this context.