rays involved in the production of radiation injuries are the alpha and beta particles, the neutron, and the gamma ray. These particles and rays produce their effect by ionizing the chemical compounds that make up the living cell. If enough of these particles or rays disrupt a sufficient number of molecules within the cell, the cell will not be able to carry on its normal functions and will die. ALPHA.—Alpha particles are emitted from the nucleus of some radioactive elements. Alpha particles produce a high degree of ionization when passing through air or tissue. Also, due to their large size and electrical charge, they are rapidly stopped or absorbed by a few inches of air, a sheet of paper, or the superficial layers of skin. Therefore, alpha particles do not constitute a major external radiation hazard. However, because of their great ionization power, they constitute a serious hazard when taken into the body through ingestion, inhalation, or an open wound. BETA.—Beta particles are electrons of nuclear origin. The penetration ability of a beta particle is greater than an alpha particle, but it will only penetrate a few millimeters of tissue and will most probably be shielded out by clothing. Therefore, beta particles, like alpha particles, do not constitute a serious external hazard; however, like alpha particles, they do constitute a serious internal hazard. NEUTRONS.—Neutrons are emitted from the nucleus of the atom. Their travel is therefore unaffected by the electromagnetic fields of other atoms. The neutron is a penetrating radiation which interacts in billiard-ball fashion with the nucleus of small atoms like hydrogen. This interaction produces high-energy, heavy-ionizing particles that can cause significant biological damage similar to that produced by alpha particles. GAMMA RAYS.—Gamma rays are electro- magnetic waves. Biologically, gamma rays are identical to x-rays of the same energy and frequency. Because they possess no mass or electrical charge, they are the most penetrating form of radiation. Gamma rays produce their effects mainly by knocking orbital electrons out of their path—thereby ionizing the atom so affected—and imparting to the ejected electron. Neutrons and gamma rays are emitted at the time of the nuclear explosion, along with light. Gamma rays and beta particles are present in nuclear fallout along with alpha particles from unfissioned nuclear material. Neutrons and gamma rays are an important medical consideration in a nuclear explosion since their range is great enough to produce biologic damage, either alone or in conjunction with blast and thermal injuries. PROTECTION AND TREATMENT Preparations for the protection and treatment of projected casualties of a nuclear attack must be made in advance of any such assault. Action before Nuclear Explosion If there is sufficient warning in advance of an attack, head as quickly as possible for the best shelter available. This is the same procedure as would be used during an attack by ordinary, high-explosive bombs. At the sound of the alarm, get your protective mask ready. Proceed to your station or to a shelter, as ordered. If you are ordered to a shelter, remain there until the “all clear” signal is given. In the absence of specially constructed shelters during a nuclear explosion ashore, you can get some protection in a foxhole, a dugout, or on the lowest floor or basement of a reinforced concrete or steel-framed building. Generally, the safest place is in the basement near walls. The next best place is on the lowest floor in an interior room, passageway, or hall, away from the windows and, if possible, near a supporting column. Avoid wooden buildings when possible. If you have no choice, take shelter under a table or bed rather than going out into the open. If you have time, draw the shades and blinds to keep out most of the heat from the blast. Only those people in the direct line of sight of thermal emission will be burn casualties; that is, anything that casts a shadow will afford protection. Tunnels, storm drains, and subways can also provide effective shelter. In the event of a surprise attack, no matter where you are—out in the open on the deck of a ship, in a ship compartment, out in the open ashore, or inside a building—drop to a prone position in a doorway or against a bulkhead or wall. If you have a protective mask with you, put it on. Otherwise, hold or tie a handkerchief over your mouth and nose. Cover yourself with anything at hand, being especially sure to cover the exposed portions of the skin, such as the face, neck, and hands. If this can be done within a second of seeing the bright light of a nuclear explosion, some of the heat radiation may be avoided. Ducking under a table, desk, or bench indoors, or into a trench, ditch, or vehicle outdoors, with the face away from the light, will provide added protection. 8-15