Q: We own a fourplex apartment building with long-term tenants in every unit. The couple upstairs has asked us to implement a smoke-free policy for the building. They claim that the smoke from their downstairs neighbors enters their unit no matter what they do, through the staircase and even the adjacent windows. The downstairs people are perfectly fine tenants, have no intention of quitting, and tell us that we can’t do anything about it. What should we do? –Wes and Judy Z.