Hood filters are designed to remove smoke, grease and other debris from the air before it hits your ventilation system. Without this line of defense, these materials would build up in your air ducts and become a serious fire hazard. In short, hood filters can help prevent devastating kitchen fires. Hood filters are installed over stoves and are designed to capture and remove smoke, grease, and debris to prevent them from getting into the ventilation system. Without these hood filters, grease, particulate matter in smoke and other types of debris would build up in the air ducts and could become a fire hazard.