Summary: Particle dispersion from a high chimney is considered, and an expression for the subsequent concentration of the particulate deposited on the ground is derived. We consider the general case wherein the effects of both diffusion and convection on the steady-state ground concentration of particulate are incorporated. Two key parameters emerge from this analysis: the ratio of diffusion to convection, and the nondimensionalised surface mass transfer rate. We also solve the inverse problem of recovering these two parameters given the boundary concentration profile, and provide an estimate of the concentration flux above the chimney stack.