The basement is an area of the home that can accumulate a musty smell. Many things can cause this odor, including lack of ventilation, lack of sunlight and/or too much moisture. Incorporate a routine that deodorizes the basement and extracts excess moisture to prevent the odor from coming back.
Place a dehumidifier in the middle of the basement and let run. This unit will pull excess moisture out of the air, preventing the musty smell from developing. Check the water tank once or twice per day and empty the water captured in the tank.
Sprinkle a dusting of baking soda around the basement, as this will absorb both moisture and odor. Let it sit overnight and sweep up with a broom or vacuum cleaner.
Open windows and let the basement ventilate. This also allows sunlight to enter and freshen the basement. Sit fans around the basement to allow air to circulate.
Fill a spray bottle with white vinegar and mist around the basement as an air freshener that will deodorize the area.