Born in Bhopal in 1972, the son of a carpenter, Verma lived in JP Nagar, near the plant run by Union Carbide, now a subsidiary of Dow Chemicals, when the gas leak occurred on 3 December 1984.
He and his family tried to escape, as the poisonous cloud of methyl isocyanate gas descended on the slum settlement in Madhya Pradesh's state capital.
The family members got separated, and Sunil Verma, with eyes burning and chest in pain, managed to board a bus that took him to Hoshangabad, about 70 km (44 miles) away.
Verma was also a member of the Bhopal Group for Information and Action, and participated in every anniversary rally to mark the disaster, as his mental health deteriorated.
Along with others orphaned by the gas, Sunil sat on hunger strike in Bhopal for six days in 2003, demanding the jobs that the government had offered years before.
After Sunil's death, many people from the Netherlands, the U.S., South Africa and other countries raised funds in his memory to establish a mental health centre.