I'd say perfume, Dr. Bill. My ex used to have to cross Mexico City from the southwest to the northeast and transfer several buses to get to his psych lab class. It would take him three hours each way. Some of the buses he needed to ride to get there were very inexpensive and many of the other passengers were not the cleanest people around. He "borrowed" my bottle of frangipani oil for these daily trips and used it in his moustache to avoid smelling the worst of it.