Studies on deposition of submicronic dust particles in the respiratory tract

Abstract

In a previous paper (1), the characteristics of the lung retention of coal dust particles (maximum size: 5μ, mean size: 0,8 µ) were studied on 3 normal subjects. By comparing inspired air, global expired air, end of tidal air and alveolar air, it was shown that the deposition rate of these particles in the global expired air and at the end of the tidal air was inversely proportional to the respiratory rate. On the contrary, the deposition rate of these coal dust particles in the Haldane-Priestley deep alveolar air was consistently observed to be above 90%, irrespective ot the frequency or of the depth of breathing. As theoritically assumed by Findeisen (2) and experimentally confirmed by Wilson and LaMer (3), Landahl, Tracewell and Lassen (4), Altshuler, Yarmus, Palmes and Nelson (5), it was also found that for every respiratory rate, from 3 to 32 per minute, the deposition of these coal dust particles in the lungs taken as a whole and at the level of the last portion of the tidal air, usually presented a minimum round about 0,5 micron. Such an inflexion towards a minimum followed by a reascending of the deposition rate could not be demonstrated in deep alveolar air samples.