Introductory Chapter: Radon Phenomenon
Live beings on earth have always been exposed to radiation from nature and more recently from artificial sources of radiation. The main components of radiation from nature are cosmic rays, terrestrial gamma ray, ingestion, and inhalation of natural radionuclides. On normal occasions, terrestrial sources are responsible for most of human exposure to natural radiation. These are, above all, radionuclides that are members of the three natural radioactive series: uranium-radium (238U), uranium-actinium (235U), and thorium series (232Th). Usually, the radionuclides on the beginning of these three radioactive chains are called primordial or primary natural radionuclides. All members of these series are genetically linked and are the result of the successive decay of the first member of the series, which explains the law of radioactive decay. Natural radioactivity is the occurrence of atomic core decomposition that exists in nature, without external influences, at which alpha particles (helium nucleus), beta particles (electrons and positron), and cosmic rays (photons) are emitted.