Loya did have one piece of advice: “Just wash your face and all this and it will be washed away.”

Satpathy assesses the dearth of information this way: “While the company was installing this factory, suppose he would have disclosed: ‘Look, gentlemen, I am installing a factory where this MIC gas will be used and even if a single puff of it will be so toxic that death may precipitate.’ Then no worker would have employed at that factory.”

MIC was produced at the Bhopal plant by reacting phosgene, the poison gas that was used as a chemical agent in the First World War, with monomethylamine. The phosgene was made on site by reacting chlorine with carbon monoxide, both of which were trucked in to the Union Carbide site. The end product, the pesticide, was produced by reacting MIC with the organic compound 1-naphthol.

By the autumn of 1984, the Bhopal plant was a chronic money loser, the size of staff had been chopped in half and safety management systems, such as they were, had been badly compromised. The MIC production unit had been shut down. Between two tanks, 610 and 611, the MIC inventory stood at 83 tonnes, which were to be stored at a target temperature of zero degrees Celsius. The MIC in both tanks exceeded recommended capacity by roughly 30 per cent. Conversion of the MIC to carbaryl, or Sevin, was deemed the soundest approach to disposing of the remaining material.

MIC is colourless, has a sharp, detectable odour, and is highly reactive with water. According to employee accounts, on the evening of Dec. 2, Rahaman Khan, also known as Rehman Khan, commenced the process of washing four lines of piping in the unit. The composition of the unit included a relief valve vent header, designed to flip open under pressure and release excess gases as required to the vent gas scrubber, the apparatus that would neutralize the gas with a caustic soda solution. Clearing such discharge pipes when blocked was common practice. But a slip blind, which would have contained the water flow and prevented it from entering the tank and contaminating the MIC, was not in place.