What are "Biological" Pollutants...and Where do They Come From?

Biological Pollutants

Biological pollutants include bacteria, molds, mildew, viruses, animal dander and cat saliva, house dust, mites, cockroaches, and pollen . There are many sources of these pollutants. Pollens originate from plants. Viruses are passed on by people and animals and bacteria are carried by people, animals, and soil and plant debris. Household pets are sources of saliva and animal dander. The protein in urine from rats and mice is a potent allergen. When it dries, it can become airborne. Contaminated central air conditioning systems (HVAC) can become breeding grounds for mold, mildew, and other sources of biological contaminants and can then distribute these contaminants through the home.
By controlling the relative humidity level in a home, the growth of some sources of biological pollutants can be minimized. A relative humidity of 30-50 percent is generally recommended for homes. Standing water, water-damaged materials, or wet surfaces also serve as a breeding ground for molds, mildews, bacteria, and insects. House dust mites, the source of one of the most powerful biological allergens, grow in damp, warm environments.
Biological Pollutants...Sources
Common biological contaminants include mold, dust mites, pet dander (skin flakes), droppings and body parts from cockroaches, rodents and other pests or insects, viruses, and bacteria. Many of these biological contaminants are small enough to be inhaled.
Biological contaminants are, or are produced by, living things. Biological contaminants are often found in areas that provide food and moisture or water. For example, damp or wet areas such as cooling coils, humidifiers, condensate pans, or unvented bathrooms can be moldy. Draperies, bedding, carpet, and other areas where dust collects may accumulate biological contaminants.