Exposed fiberglass insulation inside air ducts can release irritating fibers if it breaks down with age or water damage. Try to find fiberglass insulation with a plastic outer lining. Any kind of insulation can be a problem if it gets wet, since it can harbor molds and mildew. Because the air filters on most household vacuum cleaners are not very efficient, microscopic allergens can get into the air. New carpets, carpet backings and adhesives may release volatile organic compounds and other irritating vapors.
Many people are allergic to molds, mildew, and other fungal spores.
Some molds cause disease or release toxic substances. Molds and mildew may be in areas of your home with high humidity such as areas with improper drainage, porous foundation materials and improperly maintained humidifiers, dehumidifiers, or air conditioners. A single flooding event can create a mold or mildew problem. To avoid these problems, do not allow water to form pools or wet spots inside or immediately outside your home. Thoroughly clean and disinfect or remove surfaces where molds have grown in the past.