The world's biggest man-made disaster that no one has ever heard of and killed over 3,500 people

December 3, 1984, is a date that will be etched into the minds of Bhopal residents forever, after what is described as the biggest man-man disaster of all time wreaked catastrophic havoc across the central Indian city.

A tragic sequence of events began at 11.00pm on 2 December when an operator at the plant noticed that there was a small leak of methyl isocyanate (MIC) gas, which caused increasing pressure inside a storage tank.

Three weeks previously, a decision had been made to turn off a vent-gas scrubber, used to neutralise toxic discharge from the MIC system – this proved to be costly. It meant that a faulty valve allowed one ton of water to mix with 40 tons of MIC.

Pressure and heat was allowed to build in the tank after a 30 ton refrigeration unit used to cool the MIC had been drained for use in another part of the plant.

There was widespread and costly mismanagement at the site, with the gas flare system having been out of action for three months in the build-up to the disaster.

Then, at 1.00am, a loud reverberating sound was heard across the plant, and a safety valve allowed a plume of MIC gas to escape.

In a scene which would come straight out of an apocalyptic movie, the streets of Bhopal were lined with dead bodies, along with deceased cows, buffaloes, dogs and birds.

Hospitals were quickly overwhelmed and little was known about what gas was involved and its effects on the injured.

The fall-out from the disaster was just as messy, as the company involved tried to completely remove itself from what happened.

Eventually, the company came to an agreement with the Indian Government and paid $470 million. Much greater emphasis was placed on improving environmental safety that adhered to international standards and finding ways to prevent a similar incident happening again.

It remains unclear how much India has learned from the disaster. Despite going through a period of rapid industrialisation and seeing improvements in government policy, it is poorly regulated and the country’s poor environmental record persists this day.

This nightmare doesn’t appear to be ending any time soon, and one hopes that an incident like the one at Bhopal is never repeated again.