While delivering 4 tonnes of sodium chlorite to a textile company (wool combing and lanoline production) at around 8.30 am, the driver read the loading plan upside down and emptied the wrong tank. About 50 litres of sulphuric acid was transferred to a tank still containing 700 litres of sodium chlorite. Chlorine dioxide vapours and a cloud of sulphuric acid were soon released. The area in the immediate vicinity was evacuated. The gas initially remained confined to a building housing the tanker truck as the mechanical extraction was insufficient. When the police and fire-fighters arrived, a safety perimeter extended to 200 m was set up around the site, all the staff evacuated and the residents informed (people were advised to stay indoors). The fire-fighters disconnected and emptied the transfer hose and broke a glass part of the roof to evacuate the gas. They subsequently sprayed 5 litres of caustic soda at intervals of 15 minutes to bring the pH to 12-13 which had dropped to 6.26. Around 3.30 pm, the pH was at 13.3 and the fire-fighters left the site. No casualties were reported and the weather conditions were conducive for atmospheric dispersion. Further to this accident, the operator was asked to prepare a report along with an impact study assessing the environmental consequences of the incident.