The transport, diffusion, and dry deposition of small particle material emitted from an idealized continuous line source into the atmosphere over a forward-facing step, a backward-facing step, and a rectangular block are stimulated. The description of the atmospheric flow pattern near the obstruction is obtained by numerically solving the Navier-Stokes equations with the k-(epsilon) two-equation turbulence model. Gosman's upwind finite difference scheme which is modified to be a time marching approach is selected as the numerical method. For the estimation of the pollutant concentration and deposition the gradient-transfer model is applied. The Crank-Nicolson scheme which is modified to be the Gauss-Seidel with Successive-Over-Relaxation method is used. Comparisons and analyses are performed based on these numerical predictions of the flow fields and particulate diffusion and deposition. The result is a better understanding of the properties of the disturbed atmospheric flow and of the distribution of suspended and deposited particles near the obstruction.