The chemical element Radon is the strongest source of natural ionizing radiations for men and it is responsible of some patologies, such as lungs cancer. The concentration of this gas in houses is in Italy on average 70-75 Bq/m3. Apart from a regulative first step, represented by the 2002 Radon National Plan, at the moment there are no specified rules regarding the risks of exposition to radon in general population. On the contrary, safeguarding workers exposed to natural sources of radiation, working places are regulated by legislative decrees. In order to carry out corrective actions in case of high rates, it is necessary to correctly measure the expositional levels both with active and passive instruments. The topical knowledge about radon and its effects urge us to take preventive and reductive measures, protecting the well-being if population.