Abstract: In the paper an experimental study of atmospheric diffusion using SF6 as tracer is described. The gas chromatagraphic analysis has a sensitivity of 2×10-11, with an optimun value 5×10-12 (parts SFis per part of air). The experiments were carried out in 1976-1977 for different kinds of topography along coastal Tracer samples were taken downwind to 7 km. A distinct concentration profile of nearly normal distribution has been obtained in the crosswind direction.