An experimental evaluation of strategies for reducing airborne dust in desert cities

The effect of buildings on the dry deposition of dust was investigated in Be'er Sheva, a desert city in southern Israel, and at two reference points in the surrounding countryside. The mineral and chemical composition of dust sampled at all sites was similar, reflecting the composition of the local loess soil, its likely origin. However, dust deposited in the traps set up in the vicinity of buildings in the city was significantly coarser than the dust which accumulated in similar traps at exposed sites in the countryside. The amount of dust in the urban dust traps was on average more than twice the amount deposited in the rural area. The differences in grain-size distribution and quantity of dust are accounted for by the disturbances to the natural environment caused by the presence of buildings and by human activity in the city. This study suggests that strategies commonly employed in the design of buildings and urban space to reduce exposure to dust, such as the construction of walled courtyards, are not effective. A significant reduction in the concentration of dust in the vicinity of buildings in desert cities may require a comprehensive approach which deals with the entire urban area and its immediate surroundings, particularly with a view to reducing the availability of erodible particles by means of planting or paving all exposed land surfaces.