Deposition of fine and ultrafine aerosol particles during exposure at the air/cell interface

In vitro investigations regarding the action of aerosol particles on airway epithelial cells or alveolar macrophages are faced with the unsettled problem of controlling the number of particles deposited from the gas phase onto the cell surface (particle dosimetry). In this study we report about a new method which allows a quantitative dosimetry of fine and ultrafine aerosol particles (diameter: 75–1000 nm) during in vitro exposure of cell cultures. Combining particle transportation close to the cell surface by stagnation point flow and particle/wall contact via experimentally verified convection and the known magnitudes of Brownian diffusion and sedimentation by gravity the number of particles deposited per unit time and area of the stagnation plate could be calculated. Results of deposition experiments using fine polystyrene and ultrafine carbon black aerosol particles are in satisfactory agreement with the calculated values, indicating the utility of the proposed dosimetric method.