[en] Search for and determination of ₂₂₆Ra and ₂₁₀Po in the environment are dealt with. Emphasis is given to water and atmospheric air collected in uranium mines and ore milling enclosures. It is known that natural radioactive elements of ₂₃₈U and ₂₃₂Th series are found dispersed in the environment and may cause major or minor problems in living beings. The harmful effects occur by external exposure, ingestion and inhalation. Among the most important nuclides are ₂₂₆Ra and its daughters: ₂₂₂Rn, ₂₁₈Po, ₂₁₄Pb, ₂₁₄Bi, ₂₁₄Po, ₂₁₀Bi and ₂₁₀Po, all of them belonging to the uranium series. ₂₂₆Ra and ₂₁₀Po were chosen for this search due to several important factors: their half-life; the fact that they are high-energy alpha emitters; the chemical similarity of radium and calcium which may result in bone irradiation when these elements are metabolized; and the fact that ₂₁₀Po is a chemical and radioactive toxic agent for the respiratory system. Results are compared with permissible values according to national and international radiation protection rules. (I.C.R.)