Retention of Aerosol Particles in the Respiratory Tract1

Abstract

The purpose of this paper is to review the existing literature dealing with the retention of particulate matter in the respiratory tract, with special emphasis on the effect of particle size. Because of thc importance of inhaled dust particles as industrial hazards, exhaustive study has been done of their injurious effects. Many investigations of pneumoconiosis associated with the mining industry were carried out during the first quarter of the twentieth century. Since that time, the literature on this subject has become so extensive that much time and space would be required to review all papers dealing with lung retention. Those papers on pneumoconiosis that are concerned only with dust loading, and not with the particle-size distribution of the dust, have not been included in the present review, in whieh the emphasis is on the effects of particle size. During the past few years, interest in aerosol therapy, chemical warfare, and the dangers associated with radioactivity has resulted in numerous papers dealing with the action of inhaled particles. Most of these papers appear to have considerable merit; however, because of differences in the techniques used to determine the retention of the particles as a function of particle size, agreement on the results presented by various investigators is poor. An attempt has been made, however, to evaluate the reliability that can be placed on the data obtained by the various techniques.