Take the following scenario: the tenant of a completely furnished apartment (including bed linen and towels) keeps a cat (European Shorthair) in there. The cat roams outside a lot of the time, but he also spends a significant amount of time inside, leaving hair and other things which can cause reactions in people who are allergic to cats.
Now suppose the tenant moves out (with the cat), and 1–2 days later a new tenant with a cat allergy moves in.
What would need to be done in the apartment (beyond regular cleaning) to get all cat allergens out, so the new tenant will not have any issues?
The floors in the apartment are hardwood and tiles, with carpets placed on top in a few spots. There is some upholstered furniture (part leather, part fabric) in there, as well as curtains.