Make sure there are no windows open or drafts blowing into your crawl space to create moisture. You may need to seal the sides of nearby windows using plastic wrap and duct tape to stop the draft.
Examine the crawl space to see if there are any areas where water is seeping in. Wear latex gloves and feel around the walls and ceiling of the crawl space for any wet spots. If you find any wet spots, you may need to replace drywall to prevent mold and seal any leaking pipes.
Soak up the moisture on the floor of the crawl space by sprinkling baking soda all around the floor. Baking soda is also made up of sodium bicarbonate, which naturally eliminates odors. Let the baking soda sit for at least five minutes, and then vacuum up the powder using a hose attachment. You can continue to dry the area with an old towel.
Fill a spray bottle with 1 cup of vinegar and 2 cups of warm water. Shake the bottle to mix the ingredients together. Spray all surfaces of the crawl space thoroughly and let the vinegar mixture sit for up to 24 hours. The acetic acid in the vinegar will help to kill any existing bacteria that could cause the damp smell to continue.
Wipe up any moisture left from the vinegar using a towel. Spray an air freshener in the crawl space if any smell persists.