THE SOUTH DURBAN INDUSTRIAL BASIN (SIDIB) is known for its poor air quality. Sulphur dioxide (SO2) is a key pollutant and is monitored at four locations within the SDIB. This paper reports geographical variations in SO2 concentrations over time and discusses the relationship between the pollutant and meteorological variables. Spectral analysis showed that the dominant feature of the data was the diurnal cycle, which was particularly well developed in winter at the two stations closest to the industrial sources. Relatively high SO, values occurred in association with low wind speeds, decreasing as wind speed rose to reach a critical threshold ranging between 3.5 and 4.5 in s(-1), after which the trend was reversed. The pollution pattern was attributed to stack down-drafting in the presence of strong southwesterly winds. Analysis of high-SO2 events in conjunction with wind direction revealed that most episodes were linked to sources within the SDIB.
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