Bhopal disaster

Shortly after midnight on 3 December 1984, a storage tank at a pesticide factory in Bhopal, in the central Indian state of Madhya Pradesh, released a cloud of methyl isocyanate gas over the sleeping city. More than half a million people were exposed. Thousands died within days, and many more suffered lasting illness. Widely regarded as the world's worst industrial disaster, it raised enduring questions about corporate responsibility, safety standards and justice for victims.

The factory belonged to Union Carbide India Limited, a company majority-owned and controlled by the Union Carbide Corporation of the United States, with the rest held by Indian investors and state-controlled banks. Built in 1969 to make the insecticide Sevin, or carbaryl, it began producing its own methyl isocyanate (MIC), a highly toxic intermediate, in 1979. Other manufacturers used a costlier process that avoided storing MIC. As demand for pesticides fell in the early 1980s, unused MIC built up on site. There were warning signs: a worker died after a phosgene leak in 1981, several leaks injured staff in 1982, and a local journalist, Rajkumar Keswani, warned that Bhopal was sitting on a volcano.

By late 1984 much of the plant's safety equipment was broken, switched off or under repair. Tank E610 had held 42 tons of liquid MIC since late October, more than the company's own limit, and could no longer be pressurised to empty it. On the evening of 2 December water got into the tank, setting off a runaway reaction. Pressure and temperature soared, and soon after 00:40 the relief valve burst open. About 30 tonnes of MIC escaped within an hour, rising to 40 tonnes within two hours, and the dense gas drifted south-east across the city at ground level.

The public siren sounded briefly at 00:50 and was then switched off under company procedure; it was not sounded again until after the leak had stopped at about 2 a.m. Police calls to the plant were met with assurances that all was well. Most residents learned of the danger only when the gas reached them, causing choking, burning eyes and lungs, and vomiting. Hospitals were overwhelmed and did not know what they were treating.

The official count of immediate deaths was 2,259, and the Madhya Pradesh government later confirmed 3,787 deaths linked to the gas. Other estimates put deaths from gas-related illness at 8,000 or more, and some claims exceed 16,000. A government affidavit of 2006 recorded about 558,125 injuries, including some 3,900 severe and permanent disabilities. At least 200,000 children were exposed.

How the water entered the tank remains disputed. Workers said they had been flushing a clogged pipe without isolating the tank, and many investigators pointed to poor maintenance, disabled safety systems and inadequate training. Union Carbide argued that a disgruntled employee had deliberately connected a hose to the tank. The company's chairman, Warren Anderson, was arrested on 7 December 1984 and released on bail within hours.

The Indian government claimed $3.3 billion. In February 1989 Union Carbide settled out of court for $470 million, which the Supreme Court of India upheld in 1991. In June 2010 seven former Indian managers of the company, including its former chairman Keshub Mahindra, were convicted of causing death by negligence and sentenced to two years in prison, the maximum available, but were soon released on bail. Dow Chemical bought Union Carbide in 2001.

Chemicals left at the abandoned site have continued to contaminate soil and groundwater, and the state of Madhya Pradesh took over the site in 1998. Survivors' groups have campaigned for decades for better medical care, compensation and clean-up. On 1 January 2025 some 377 tons of hazardous waste were finally trucked from the site for incineration at Pithampur, despite local protests.

Our 1985 map shows the Republic of India at the time of the disaster.