Morphological Analysis of Fallout Dust in Windhoek, Namibia

In this study, the morphological characteristics of fallout dust particles from three locations within Windhoek were determined using Olympus BX40 light microscope and the composition and possible sources of the dust were estimated. Single bucket fallout monitors were deployed following the American Society for Testing and Materials standard method for collection and analysis of dust fallout to determine the dust concentrations. The common particles in the Windhoek dust were successfully observed using a light microscope as cloudy and brownish spherical, brownish and black crystalline, black irregularly shaped, and clear (crystal-like) sharp-edged . Based on the photomicrographs produced, the possible sources of fallout dust in Windhoek North and Khomasdal were identified mainly as road/traffic dust and coal-burning activities, with some milling, grinding and abrading activities possibly from building construction activities; while the dust in the Oshandumbala area showed possible main contributions from the local coal-fired power plant, building materials and road/traffic dust. Minimum and maximum concentration levels of fallout dust were determined per sampling location as 618.3 and 3102.1 for Windhoek North; 498.9 and 2995.5 for Khomasdal; and 741.7 and 43966.1 mg/day/ m² for Oshandumbala.