Which type of radiation is considered the most harmful and can pass through a person?

Gamma rays are considered the most harmful type of radiation because they possess high energy and short wavelengths, allowing them to penetrate various materials, including human tissue. This penetrating power means that they can pass through the body, potentially causing significant damage to internal organs and cells. Their ability to traverse solid barriers makes them particularly dangerous in situations involving radioactive sources.

In contrast, alpha rays, which consist of helium nuclei, have very low penetration abilities and can be stopped by a sheet of paper or even human skin, making them less harmful in terms of external exposure. Beta rays, which are high-energy, high-speed electrons or positrons, offer some degree of penetration, able to penetrate the skin but are generally stopped by materials like plastic or glass. X-rays also have penetrating capabilities, similar to gamma rays, but they typically have lower energy than gamma rays and are predominantly used in medical imaging rather than posing a hazard from radioactive sources. Thus, in terms of penetration and potential harm, gamma rays lead as the most dangerous form of radiation.