Using theories for diffusive and thermophoretic deposition available in the literature, a model was compiled for the estimation of the penetration rate of aerosol particles through pipes. The numerical results of the model were tested by a few experiments, and its practical applicability has been demonstrated. A realistic case with diesel exhaust as the test aerosol and high penetration rates (about 90%) was chosen. The soot aerosol turned out to be bimodal (120 and 2400 nm approximately, GSD > 2).