Taking shower for a long time or hot bath may damage your health afterwards. The humidity in the air creates good conditions for mold and mildew that deteriorate wood, drywall, wallpaper, paint, and other building materials. They also may cause allergies and other health issues. The bathroom fan will not only freshen up the air but also remove the mold spores and the unpleasant odor. Bathroom fans are easy to install and are cheap, so in case you have an exhaust fan it can be easily replaced.