The paper summarizes a study of the relationship between Gaussian plume models and wind-tunnel models. Wind-tunnel measurements of the distribution of tracer concentrations downwind of a point source in the near wake of a rectangular model building were evaluated. Profiles of mean velocity and turbulence were measured to characterize the flow. These experiments were conducted in both a low-turbulence boundary layer and a simulated-atmospheric boundary layer. The study covered a range of four flow speeds and four different sized buildings. The differences in observed velocity and concentrations between the results for the low turbulence and simulated atmospheric boundary layer flow were not significant very near the building, but these differences increased in significance at downstream distance greater than 10 times the building height. The transition from building-affected dispersion levels to levels that were not significantly different from dispersion without a building was a function of the size of the building. The application of a modified Gaussian plume model showed it to be a simple, well-suited complement to wind-tunnel measurements of mean concentrations.