In this case the problem is permanent. Your son must change and get a new condo. Or he should fix an exhaust fan in it. He can try some window in its walls. Or some holes which can solve the problem.
The Bathroom In My Son's Condo Has No Exhaust Fan Nor Window. How Could The Humidity Be Vented ?
I don't know where you are BUT in any bathroom without a window THE CODE AND LAW requires an exhaust fan, period!
SOMEONE HAS to install one! It's a health issue!
And has to be addressed!
Plumber 101
SOMEONE HAS to install one! It's a health issue!
And has to be addressed!
Plumber 101