Are they trying to derail smokers?
Do these people also complain about inhaling diesel fumes from the train itself? Diesel fumes are a designated carcinogen, or cancer-causing to humans.
Do the complainers object to inhaling everything that fellow passengers exhale also? Do they have a problem inhaling the flatulence of other travellers? How do they feel about the germs of others that they inevitably come in contact with? The perfumes and aftershaves of others must surely drive them wild. Perhaps they should demand a carriage to themselves.