were not close enough to be destroyed by the thermal flash (heat) or blast wave (pressure) would probably be bombarded with neutrons, gamma ravs, and possibly alpha particles at a rate that would decrease with the increase of their distance from the center of the explosion. The alpha particles are of biclogical importance only when they are emitted from inhaled or ingested material, Neither are of importance for irradiation by external sources following nuclear explosions. These same effects, however, would also be experienced by a person being in, or going into, an area where there is heavy radioactive fallout, In such an area, he would be exposed to gamma radiation and beta radiation from the fallout material. In terms of external exposure the gamma radiation, because it is able to penetrate or pass through the bhodv, would be the most harmful. The beta radiation, which has lower energy, would mainly be dangerous externally if the material of the person. fellon the hair or uncovered skin While beta particles are not deeply penetrating (generally only the upper layer or layers of the skin) they can--in sufficient quantity and if of enough strength--cause loss of hair and skin "burns" in several degrees, from light to severe, “Beta burns," then, are dangerous in the sense that if a person received a gamma dose high enough to lower blood cell counts and thus resistance to infection, and a beta skin burn became seriously infected, the person could die as a result. Internal Exposure As has been described, human beings can be exposed directly to radiation either through closeness to the original explosion of a nuclear weapon source of radiation) or through exposure to radioactive fallout. (or A second