Then, common consideration used to hold that eating in front of others that aren't eating is just plain rude. But on the flip side, some think it's absolutely OK to eat on the train, as long as you clean up after yourself, particularly if you're trying to squeeze a meal into an otherwise hectic day.

The social etiquette of eating on a subway varies significantly by global city, but generally, it is considered a breach of "commuter etiquette" if the food is messy, odorous, or intrusive. In cities like New York or London, eating is technically permitted but often frowned upon if you are consuming something pungent (like tuna or curry) or something that creates crumbs. In contrast, in cities like Tokyo, Singapore, or Taipei, eating and drinking on the subway is strictly prohibited by law and can result in heavy fines; these systems prioritize pristine cleanliness and a shared sense of public order. Beyond the smell, eating on a crowded train is seen as inconsiderate because it takes up extra personal space and carries the risk of spilling onto other passengers. If you must eat, most etiquette experts suggest "discreet snacking" like a granola bar or a closed beverage, while saving the full hot meal for the platform or your destination to respect the shared air and environment of the cabin.