TOTAL RESPIRATORY DEPOSITION OF RADON DAUGHTERS FROM INHALATION OF URANIUM MINE ATMOSPHERES

Total deposition in the human respiratory tract of the short-lived radon progeny present in a “typical” uranium mine atmosphere was determined in thirty separate experiments. Effective diffusion coefficients for the total radon progeny activity were determined by diffusion tube sampling of the exposure atmosphere, and concentrations of RaA, RaB and RaC were measured in both the inspired and exhaled air. Respiration rates and tidal volumes were also measured for each experiment. Total percent Working Level depositions, defined by the relationship: 100 [1 - (WL in exhaled air)/(WL in inspired air), were in the range of 30–65%. Percent depositions for individual radon daughters were also measured, with mean values of 50.4%, 44.7% and 40.6% determined for RaA, RaB, and RaC, respectively, for an average respiration rate of 18 min-1 and an average tidal volume of 1.2 l. The experimentally determined relationships between total deposition and respiratory rate and tidal volume are presented. © 1969 Health Physics Society.