[en] The biological effects of radon on the lung arise primarily from the alpha decay of the short-lived decay products of radon inhaled. Radon is chemically inert and so is distributed throughout the body according to its solubility in the various body tissues. The daughter products are isotopes of polonium, bismuth, and lead, which are treated individually by the tissues and fluids, within the confines of their brief half-lives. Experiments with inhaled decay products indicate the dose to lung is much greater than to the rest of the body. Extensive injury was done to the bronchial tree, but the lesions did not lead to bronchial tumors. After irradiation ceased, these lesions were quickly repaired. Permanent changes, but no cancer, were seen in the region of the respiratory bronchioles. Compared to other alpha emitters in the lung, the alpha radiation from radon is particularly inefficient in producing radiation-specific tumors. The conclusion is taken that the radiation effects of alpha emitters may be inconsequential compared to the chemical effects of the alpha emitters