ABSTRACT
There are three natural radioactive Series in the earth’s crust: uranium, thorium, uranium actinium series, each series has a radioactive gas radon isotopes, these natural radioactive series will release radon atoms can transfer in attenuation of fission, Radon atoms may enter the connected micro crack can transfer free radon formed gap the migration of radon atoms, in porous media, micro-fracture and fracture by diffusion, convection mechanism of migration to the soil surface, eventually leaving soil surface into the surrounding air. So the radon distribution in the nature is very wide, each corner exists in human activities. Radon is a recognized carcinogen, radon and its progeny is human long-term inhalation, the body will increase the incidence of cancer (Liu 2009). Important means of efficient and accurate measurement of radon concentration in the environment become the environmental assessment, disease control.
