Workers rescued after chemical incident in Melbourne.

A factory was forced to evacuate and four workers needed to be rescued after a drum containing chemicals exploded at the site in the Thomsatown area of north Melbourne in Victoria, Australia, on Saturday 10 September 2016. The four workers took refuge in a safe area within the plant after the drum burst, releasing a clound of orange gas and about 100 litres of fluid. They were rescued by emergency crews from Melbourne's Metropolitan Fire Brigade using breathing apparatus, and checked for signs of contamination by crews from Ambulance Victoria before being released. A 250 m exclusion zone was set up around the site while the spill was cleaned up.

Emergency crews at the scene of the 10 September 2016 Melbourne chemical incident. Paul Stacchino/Twitter/ABC.

The drum that caused the incident is believed to have contained nitrous acid, HNO₂, a weak monobasic acid used in a variety of chemical manufacturing proceses and not generally considered a high risk substance (and not to be confused with the similar sounding but much more dangerous nitric acid). The problem is thoguht to have occured because the drum had not been cleaned before use, and contained traces of an organic solvent; acids tend to react strongly with such solvents, producing large amounts of gas, which would have led to the presure rising sharply inside the drum, untill this led to the top being blown off.

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