The world came to know of Bhopal because of a tragedy that struck the quaint city 27 years ago. Even today, Bhopal has not fully recovered from that shock.

On the night of December 2-3, 1984, as the people of Bhopal in Madhya Pradesh slept, a tragedy unfolded. A series of events caused methyl isocyanate (MIC) to leak from a chemical plant in the city. It caused mayhem. Thousands died; animals too were affected. The city was overwhelmed. Years later — even today — thousands more suffer, affected with severe and permanently disabling injuries.

Bhopal has been called one of the world's worst industrial disasters. As a resident put it, “Mothers didn't know their children had died, children didn't know their mothers had died and men didn't know their whole families had died.”

How did it happen? Water entered a tank containing tons of MIC at Union Carbide's plant. There was a reaction and toxic gases exited into the air. As there were fairly strong winds blowing over Bhopal at that time, the gas spread. It was disaster.

The factory was shut. Days went past and the government put the death toll at around 3,500, with 15,000 people having died since then. Activists say the figure is as high as 25,000, with survivors and their dependants still suffering from the ill-effects of the leak. Their medical conditions are multiple, which includes afflictions such as loss of vision, breathing problems, kidney and liver failure and birth defects.

Union Carbide paid a compensation of $470m in 1989.

But years after the tragedy, though there have been attempts to offer relief and rehabilitation, society and the official world seem to have forgotten the victims and their plight.

Days after the disaster, the media went about the grim task of documenting the tragedy. One of the most riveting images that got the attention of the world was a stark black and white picture of a child who was about to be buried. And who was the photographer?

The photographers, Pablo Bartholomew and Raghu Rai, rushed to Bhopal on hearing the news of the disaster. Says Rai, “There was a high possibility of journalists and photographers being physically affected by the chemical contamination. But then, there is always an element of risk in any assignment.” Rai and Bartholomew soon came across a man burying a child. Rai said, “So many bodies were being buried, and this child I photographed, I must have taken six, eight frames, and they were about to pour mud on it ... I didn't want the moment to be covered up and buried away because, for me, this expression was so moving and so powerful to tell the whole story of the tragedy.”

The two photographers did not ask the identity of the man burying his daughter and no one has claimed to be her relative. In fact it is this picture, titled “Burial of an Unknown Child,” which quickly became the face of the tragedy. Rai has completed a documentary project on the chemical disaster and how it has affected its victims. The book is called “Exposure: A Corporate Crime” and exhibitions using its images have gone around Europe, America, India and Southeast Asia. Rai's aim was to get the exhibition to support the many survivors of Bhopal.