It honours those who died in the Bhopal Gas catastrophe on December 2nd and 3rd in 1984.
Approximately 45 tons of methyl isocyanate escaped from an insecticide plant to environment.
The day is dedicated to encourage the adoption of pollution control acts to prevent the environmental pollution caused by human negligence and industrial emissions.
In India, around 7 million people die due to air pollution each year, of which 4 million are killed by indoor air pollution.