[Importance of studying exposure of the population to radon and its daughters].

In recent years, several evaluations of human health risks and estimations have been made in regard to the dose-response relationship and lung cancer risk attributable to inhaled radon daughters. Inhalation of radon and thoron daughters leads to deposition in the human respiratory tract and consequent irradiation. Deposition depends on various factors, such as the size distribution of aerosols to which the daughter products of radon are attached, and fraction of unattached daughters. On average, the dose to the basal cell layer in the lung is about 5 to 8 times higher than the dose in the pulmonary region.