i smell cigarette smoke in my non smoking house... I believe that it has something to do with the house location and ventilation system.  Neighbor across the street smokes in his porch after he eats.  I think my sensitivity to smoke and any man made materials increased my 100 fold since mt total thyroidectomy 5 years ago. My nose detects hidden smells that no one else does.  My issue is how to address it, as the smoke parks in my office and master br, and i am sure is accumulating and harmful.. Thinking an air purifier may help.  Will try and report back.