Steam on the mirror is normal for a shower. Moisture lingering for
hours is a different story. I often start with the bathroom fan: is it
actually used, is the grille clogged with dust, and does it exhaust
outside?
Turn it on while bathing and leave it running long enough to clear
the room, following the fan’s instructions and your needs. With power
off, clean an accessible grille as the manufacturer directs. Dust
buildup can restrict airflow. Observe the outside termination from safe
ground if visible, and note whether its flap is blocked by lint, a nest,
or debris. Don’t climb into an attic or pull apart a wired fan just to
check a concealed duct.
A fan that rattles, barely moves air, or exhausts into an attic needs
a qualified electrician or ventilation contractor. An undersized or
poorly routed duct may be the real problem. The EPA’s
moisture guidance recommends exhausting bathroom moisture outside.
Repeated condensation, peeling paint, or mold growth is a reason to look
past a simple grille cleaning.
A timer switch can make it easier to use the fan consistently, but
electrical work and compatibility need checking. For local
professionals, see my Helpful
Resources directory. The tools
and supplies page has useful moisture monitoring ideas if the room
stays damp.