That's not an externality. And honestly, your chosen example is rather unpleasant. An externality is something like "cigarettes produce smoke that contains a l

That's not an externality. And honestly, your chosen example is rather unpleasant. An externality is something like "cigarettes produce smoke that contains a lot of carcinogens, and therefore cigarette smoking can contribute to the poor health of people who are nearby even if they do not choose to smoke themselves."