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The Highveld region of South Africa contributes substantially to the aerosol loading over southern Africa because of its importance as an industrial, mining and farming base. Measurements of aerosol optical thickness (AOT) from the ground to the top of the atmosphere and aerosol size distribution characteristics over the Highveld region were taken using hand-held hazemeters and a CIMEL sun photometer. In the 2002 winter sampling period, the AOT530nm ranged between 0.05 to 0.7 with an average of 0.14. In the 2002 summer sampling period, the AOT530nm ranged between 0.05 to 0.6, with an average of 0.24. In the 2003 winter sampling period, the AOT500nm ranged between 0.06 to 0.6, with an average of 0.21. The �ngström exponent value had a wide range, 0.8 to 2.4 in the 2002 winter and summer sampling periods and also in the 2003 winter sampling period, indicating that a range of particle sizes was present over the Highveld region. These results could help other scientists or policy makers, shed some more light into whether it is true that industry does indeed contribute more to the pollution over the Highveld than either agricultural or residential areas.

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Thomas A Bigala M.Sc: Studied Environmental Science at the University of the Witswatersrand. Admin Officer at Climatology Research Group, Johannesburg

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