Saroj Bhattacharjee, 81, calls it the “biggest trauma” of his life. The Edmonton man was a maintenance engineer at Union Carbide in Bhopal, India, in 1984, when the toxic gas methyl isocyanate leaked from a storage tank.

Considered the world’s worst industrial incident in modern times, the Bhopal gas tragedy was a chemical accident at a pesticide plant in Bhopal, Madhya Pradesh, India.

Forty years after the Bhopal disaster on December 2-3, 1984, several hundred tonnes of toxic waste still remain around the ill-fated Union Carbide plant. Despite pleas from locals and activists — bolstered over the years by orders from the National Green Tribunal and the Supreme Court — to dispose of the waste,