[en] Radon is a natural radioactive gas and a product of uranium decomposition which can accumulate in the confined atmosphere of some buildings. It is responsible of about a third of the overall exposure of the French population to ionizing radiations and the risk of lung cancer is the reason of its monitoring in dwellings. The abatement of radon levels in buildings is possible by the implementation of very simple techniques which are presented in this article: 1 - general considerations about radon (origin, contribution in the population exposure, migration from the ground to the atmosphere, measurement); 2 - domestic exposure in France (campaigns of natural irradiation measurement, results); 3 - evaluation of cancer risk linked with radon inhalation (low exposure during long periods, different possible epidemiological approaches, observed results, risk measurement); 4 - recommendations (European Union, France); 5 - techniques of radon abatement (passive techniques, active techniques); 6 - conclusion. (J.S.)