We have recently moved into a rental apartment (built early 1990s). The previous resident was a smoker, and there is a distinct smell of cigarette smoke. She lived there for 15 years. The apartment was newly painted before we moved in. There are no carpets, curtains, or wallpaper. It has parquet flooring. We took over a few pieces of furniture but none with fabric or leather (only wood and glass). We have tried to spray with a household "anti-tobacco smell" product (brand febreze), but the smell returns within hours. People with similar problems report they are still facing the smell after 10 years.
What measures are effective to permanently remove the source of old cigarette smell? Google Search results in a wide variety of partly contradictory recommendations. This company claims that their ozone generator is more effective than household products, but wikihow states that If the smell has sunk into the walls, floors, curtains, and furniture, you may not get the smell out all the way. Others recommend salmiak, Febreze, candles, orange or sandarac. But overall, advice varies from "clean well" to "only a complete renovation will work"; for each advice short of complete renovation there is another advice claiming it doesn't work. Incidentally, we are in Germany and the landlord may be legally responsible to fix it, but that is a question for another site.
Advice on the internet is anecdotal and contradictory. I'm a scientist and am interested in a permanent, evidence based solution. Short of burning the building down and rebuilding from scratch, what measures will permanently and completely remove the source of old cigarette smell from the previous resident?