An exhaust fan in the kitchen, often installed above the stove top, will help remove smoke from burning food and exchange it for fresh, outdoor air. The fan will also remove unpleasant-food odors from the room. When boiling water, steam will often fog windows or other surfaces. An exhaust fan will remove the steam from the room.
An exhaust fan in the bathroom will effectively remove unpleasant odors from the room. The fan will also aid in removing excessive steam produced from hot running water. Removing the humidity in the remove helps lower the risk of mold growth or structural damage from high moisture.
An exhaust fan in the laundry room will help lower the temperature in the room and release steam that may escape from the dryer. The fan will also remove harsh vapors from bleach or laundry detergents.