Mold and mildew can be hidden everywhere around your house. In order to eliminate it make sure your place is equipped with proper ventilation, use mold inhibitors in your paints, and clean your kitchen and bathroom regularly once you observe any sign of this danger. Besides that, get proper air conditioning and heating system in order to avoid external moisture, or get professional air duct cleaning services . Dehumidifiers and air purifiers can also help in combating bacteria, mold, and viruses.