HUMAN BRONCHIOLAR DEPOSITION AND RETENTION OF 6-MU-M, 8-MU-M, AND 10-MU-M PARTICLES

Three groups, each consisting of 6 healthy subjects, inhaled, respecti vely, 6-mu m (aerodynamic diameter), 8-mu m, and 10-mu m Teflon partic les, labeled with indium-111. The particles were inhaled at an extreme ly low flow rate, 0.05 L/s. Lung retention was measured after 0, 24, 4 8, and 72 h. Two models were used to calculate particle deposition in the lungs in the various generations: the Karolinska Institute model ( KI model) and the University of Southampton model (US model). From the experimental clearance data and the theoretical deposition data, it w as calculated that the average retention after 24 h was around 100% fo r particles deposited in generations 13-16 (ciliated bronchioles) and around 20% in generations 0-12 (both large and small ciliated airways) . In these calculations, it was assumed that the retained fractions we re independent of particle size. The depositions in the bronchial regi on (generations 0-8), bronchiolar region (generations 9-15 or 9-16), a nd the alveolar region were calculated using the two models and compar ed with the recent ICRP model. On tile whole, the three models agreed fairly well.