INTRODUCTION RADIATION IN GENERAL Man lives in a naturally radicactive environment. He is surrounded by radioactivity much as he is by the great ocean of air which envelops the world. Like air, we cannot see radioactivity with the naked eye, but we know it is there because its effects can be observed and its presence can be measured with special instruments. If we could give color to the radioactive rays which are naturally present in our environment, we would behold a wondrous display of activity. We would see these rays emanating from the wood of our houses, the rocks and soil of land, from living plants and trees, and from cement buildings and metal structures. In addition to this, we would see radiation and other rays passing through the air from television sets, power plants, wristwatches, paint, Canned foods, the milk we drink, and from the X-ray and other ray-producing machines in doctors' and dentists' offices and in hospitals and research institutes--not to mention facilities which produce radic..:tive materials and facilities which use them, like atomic power plants. We could see them shooting out from the sand of a beach, fresh-water lakes, fish, birds, and animals, the ocean, We would also see cosmic rays from deep in space stabbing through the atmosphere and actually passing through our bodies, and other matter.* Finally, if we could see inside our bodies, we would also see rays emanating from different areas--the result of certain radioactive elements, such as potassium, which are possessed naturally *Some cosmic rays are so powerful, in fact, that they have been recorded cd in mines over a quarter of a mile (1320 feet) below the earth's surface. 1o14b05 (46)