Certified Industrial Hygienist Practice Test

The correct choice is gamma and X-ray radiation because these types of radiation have very high energy and deep penetrating ability, making them more challenging to shield compared to other forms of radiation. Lead is a dense material, and its high atomic number makes it very effective at attenuating gamma and X-ray radiation. This is primarily due to the photoelectric effect and Compton scattering, which occur when these high-energy photons interact with electrons in the lead atoms, effectively blocking and reducing the intensity of the radiation that can penetrate through the shielding material.

In contrast, alpha particles, which consist of two protons and two neutrons, are relatively heavy and can be stopped by just a sheet of paper or even the outer layer of human skin, so they require far less dense materials for effective shielding. Neutrons, on the other hand, require materials that are rich in hydrogen (like polyethylene) for effective attenuation because lead is not very effective against neutron radiation. Beta particles, which are fast-moving electrons or positrons, are best shielded with materials like plastic, glass, or aluminum, as lead is not particularly effective against them.

Hence, lead is most suitable for providing protection against gamma and X-ray radiation, making it the best choice for shielding in environments