Molds, mildew, fungi, bacteria and dust mites are biological pollutants. Mold grows on organic materials such as paper, textiles, grease, dirt and soap scum.
Mold spores float throughout the house, forming new colonies where they land.
Mold, mildew, fungi, and bacteria are often found in areas of the home that have high humidity levels, such as bathrooms, kitchens, laundry rooms or basements. Dust mites thrive on dead human skin cells and in bedding, carpeting and upholstery. When these areas are disturbed during vacuuming, making beds or walking on carpet, the dust particles become airborne. The same is true of animal dander. Biological pollutants can cause allergic reactions.