UC Irvine

It has been suggested that highly concentrated aerosols exhibit colligative behavior due to hydrodynamic interactions among particles. Such behavior includes enhanced settling rates (cloud settling) and possibly increased deposition efficiency upon inhalation. The purpose of our study was to determine whether or not concentrated sidestream cigarette smoke would deposit in an enhanced manner in hollow models that represented human nasal airways. Sidestream smoke wisps were generated by smoldering 1R3 University of Kentucky research cigarettes and were drawn horizontally through the models. The smoke aerosol had a mass median aerodynamic diameter of about 0.45 μm and a geometric standard deviation of about 1.3. Photographs indicated that the smoke consisted primarily of wisps that had characteristic diameters of about 0.3 mm and lengths that were typically greater than 1 cm. These wisps, which were surrounded by relatively particle-free air, were the entities that might exhibit cloud-like behavior. The average measured percentage deposition efficiency of cigarette smoke in the nasal casts was 4.5 ± 0.2 (SE). This value is close to what one would expect for particles of 0.45 μm aerodynamic diameter. Colligative behavior did not appear to produce measurably enhanced deposition in the surrogate nasal models. © 1994.