Yes, even though Francis I of France bought the Mona Lisa in 1517 and hung it in his bathroom ! Bathrooms then were different from bathrooms now.
A damp, place is obviously bad but a very dry atmosphere is very bad too. Some humidity has to be kept, together with a constant, modest, temperature, for perfect preservation.
These two are right Birdie, and to clean them, just brush over them very carefully with a feather duster. Humidity and condensation affects oil paintings badly.