This research project deals with the distribution of radon concentration in the environment and its health consequences for young people. Epidemiological correlations will also be investigated in addition to particularly severe conditions of chemical and radioactive pollution. Preliminary studies in the region of Kuzbas (Siberia) showed that the concentration of radon both in coal mines and in housing near the mines is 3 to 15 times higher than the level recommended by the European Community. The prevalence of cancer among children (leucosis) is higher in these areas than in others. The effect of high radon concentrations will be analyzed and different investigations will be conducted on the health of the population affected by the activities of mining (Russia and Ukraine), a uranium plant (Kazakhstan), curie-therapy treatment in a hospital (Kazakhstan), and of specific situations such as the Chernobyl disaster, nuclear-weapons testing sites and radioactive waste storage. The main goal of this project is to assist the participants from the NIS in the collection of pollution data (radon, gamma and chemical data) and to analyze their effects on the population. It is also planned to set up a data bank of the radioactive and chemical situation in different regions of Russia, Ukraine and Kazakhstan. This project will define the risk of manifestation of oncological diseases as a function of radon concentration. One participant will define a mathematical model, built on the collected data of this project, which will evaluate the risk of radon as a function of the chemical, radioactive and radon levels at one site. The results will therefore lead to the creation of methods for preventing health risks for the population. Other expected results are: the validation of Russian measurement techniques for radon concentration; the creation of a databank consisting of parameters of specific sites such as coal mines, uranium plants, hospital, and such as radon concentration, environmental radioactivity level (gamma measurements) and chemical and sanitary pollution levels (e.g. number of pulmonary sicknesses, leukaemia). The data bank will lead to a mathematical analysis model which will correlate the radon concentration and the health risk probability for the population, notably the youngest part.