I guess I wasn't the first to ask. https://www.conserve-energy-future.com/smoking-effect-environment-infographic.php
Cigarette smoking emissions aren't enough to be a significant enough contributor to greenhouse gas emissions that we consider it in En-ROADS. All the coal that power plants worldwide are smoking is clogging up our atmosphere much worse.
Going through Module 4, had an odd thought. Is tobacco use worldwide significant enough to be considered in this model?