Some, such as pollen, are generated outside the home. Mold and mildew are generated in the home and release spores into the air. Mold, mildew, fungi and bacteria are often found in areas of the home with high humidity levels, such as bathrooms, kitchens, laundry rooms or basements. Dust mites and animal dander are problematic when they become airborne during vacuuming, making beds or when textiles are disturbed.
Allergic reactions are the most common health problems associated with biological pollutants.
Symptoms often include watery eyes, runny nose and sneezing, nasal congestion, itching, coughing, wheezing and difficulty breathing, headache, dizziness and fatigue. Dust mites have been identified as the single most important trigger for asthma attacks. Molds and dust mites thrive in areas of high humidity. 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.