Definitions for "ALPHA PARTICLE RADIATION"
Alpha particles are positively charged particles made up of two protons and two neutrons. They lose their energy quickly and do not penetrate the surface of the skin when exposed externally. Alpha particles can enter the body through a cut in the skin, by ingestion or inhalation. Alpha-emitting particles are harmful once inside the body. Uranium-238 and plutonium-239 are sources of alpha radiation.