I purchased a building over a year ago in Iowa and have one remaining long term tenant (11 years). He's elderly, has emphysema, smokes at least 2 packs of cigarettes a day. He refuses to stop smoking indoors (he can barely walk to smoke outdoors) and has guests who smoke in his unit as well as common areas despite our requests of no smoking in common spaces. He pays his rent on time and otherwise is a great tenant. He has a month-to-month lease as well and his rent is below market rate. The issues are now with other tenants affected by the non-stop smoking and smell. Other tenants (non-smokers) have complained their units and clothes smell like smoke. Additionally, a "new" tenant has asthma and is worried about her health.  I have resisted raising rent because I feel for the guy. I know, I know.....business, but he's also been there over a decade and I am torn on what to do. We've renovated all of the units but his since he is the only tenant who has stayed. We've spent so much on bringing the building back to life after being ignored for years so I want to protect our investment but also want to remember the human factor. Thoughts and ideas? Truthfully, I would not like him to stay.