What Does a Dehumidifier Do - A dehumidifier is an appliance designed to reduce the moisture content in the air and maintain a comfortable humidity level in indoor spaces. It works by drawing in air, removing excess moisture from the air, and then releasing drier air back into the room. The primary function of a dehumidifier is to help prevent the growth of mould, mildew, and dust mites, which thrive in humid environments. It can also help alleviate symptoms of respiratory issues and allergies caused by excessive moisture in the air. Dehumidifiers are commonly used in basements, bathrooms, laundry rooms, and other areas prone to high humidity.