Estimation and evaluation of exposures from a large sulfur fire in South Africa

A massive fire at a sulfur stockpile in the Western Cape Province of South Africa in December 1995 is estimated to have released over 14,000 t of sulfur dioxide (SO(2)) over a 20-h period. High and persistent winds greatly reduced the effectiveness of fire-fighting activities and increased the severity of impacts. Nearby urban and agricultural areas were seriously affected. Thousands of people were evacuated from the nearby town of Macassar located 2.5-4 km downwind, and at least several deaths occurred. Agricultural impacts ranged over a broad area extending to 30 km from the fire site and included severe damage to plants and some animal deaths. This paper describes the chronology of the fire, the emergency responses, and the immediate impacts. SO(2) concentrations are estimated using dispersion modeling, and predictions are evaluated using available monitoring information. Sensitivity analyses are used to test unknown or uncertain model parameters. The SO(2) concentrations estimated in Macassar reached extremely dangerous levels, at times over the IDLH level (100 ppm). Predictions agree with the available but very limited monitoring data, as well as with the symptomology of Macassar residents and plant damage patterns. Procedures to deal with the limited information and variability in this fire and similar incidents are suggested. The fire is a tragic demonstration of shortcomings in hazardous material management and emergency response.