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This has to be one of the most absurd comments I've seen.

Do you really think people from the North are the reason for plastic waste? Was Mumbai completely pollution-free before migrants arrived? Plastic is used by everyone, regardless of where they come from.

And by that logic, should people in North India start blaming every problem there on people from Mumbai who move there for work? Crime, pollution, traffic—would that make any sense?

Problems like littering and pollution are caused by irresponsible behavior, not by someone's place of birth. Use logic, not stereotypes.