The work shows the pattern of formation of radiation load on red bone marrow under the influence of radon. The study is based on the process of radiation decay of radon with the formation of a lead radioisotope (210Pb). The calculation of the dose load was carried out in the following sequence: inhaled radon, radon entering the blood, distribution of the formed lead isotope, localization of lead-210 in the bones and irradiation of the red bone marrow with this radioisotope as the main hematopoietic system. The issue of the significance of the accumulation of radioactive lead in flat bones as a factor in chronic irradiation of the hematopoietic system and the associated health risks is considered.