The wind shear generated on a local scale by the diversified relief’s impact can be a factor which significantly modifies the spatial pattern of PM₁₀ concentration. The vertical profile of PM₁₀ over a city located in a large valley during the events with high surface-level PM₁₀ concentrations may show a sudden decrease with height not only due to the increase in wind speed, but also due to the change in wind direction alone. Vertical aerosanitary urban zones can be distinguished.