Viscosity, an important aspect in air flow at the lowest layer of the atmosphere was determined during Harmattan period as 1.88 x 10-5 Nsm-2 ± 0.04%. Kinematic viscosity, another important parameter on atmospheric motion was established as 0.54 x 10-5 m2s-1 ± 0.02%. For contribution to protection of human and ecological systems from dangerous levels of air pollution, a new technique for determining the efficiency of aerosol sampler is presented. The technique incorporates the application of the physical parameters of the sampler, which include the axial length (L) of the equipment that a particle should travel before impaction on filter, the effective area (A) of the filter which matches the opening of the stacked filter unit and the thickness (t) of the filter used in the equipment. Thus, efficiency, E = 1- exp(-0.251Aα/πLt). And α is the ratio of the bulk density of the filter to the density of the fibre. By applying this relation, the efficiency of the air sampler used in this work was established as 70.4% ± 0.03.