Biological pollutants include microorganisms (alive or dead) and the waste created by living things (hair, dead skin, dried feces/urine, etc.). Biological pollutants are a major source of indoor air pollution, causing health problems that range from mild to severe. Biological air pollutants are able to travel through the air, through ventilation systems that do not utilize high-level filtration, and can even damage surfaces inside and outside the home.
There are a number of places that are at high risk for creating or collecting biological pollutants. Bedding can collect shed skin, dust mites (that gravitate to areas of shed skin and warmth), and bacteria and viruses that people have been carrying. Bedding should be washed regularly with baking soda, vinegar, or in hot water to prevent the buildup of these contaminants.
Carpets capture and hold a tremendous amount of pollution that can easily get stirred up every time someone walks around on it. And carpets in damp areas are an ideal place for mold to grow. Humidifiers and dehumidifiers are often breeding grounds for bacteria when they are not used or cleaned properly. Bathrooms and kitchens that do not have proper ventilation can develop enough humidity to grow mold spores. Laundry rooms have the same problem without sufficient ventilation, as do attics and basements.
Poorly-kept heating ventilation and air conditioning (HVAC) systems can be loaded with a variety of bacteria, viruses, and a large collection of dust mites (dead and alive) and their feces. They circulate these particles through the air endlessly until the system is cleaned or replaced and a proper filtration system is installed. Closets on outside walls often create a dark, warm environment ideal for microorganism growth.
Leaking roofs and windows can be a source of biological pollution as can a basic lack of cleaning. Refrigerator drip pans are often overlooked but may act like a petri dish gone awry without regular cleaning.
Cats, dogs, and other furry pets shed dander, hair, and the pollens and other tiny contaminants they collect running outside. They also carry a number of microorganisms in from outside on the enormous surface area their fur creates.
In heating or air conditioning (HVAC) systems that do not have high-level filtration, microorganisms can circulate throughout the building through the ventilation systems. It is important to use an HVAC filtration system to continually filter these particles out of the air, to regularly check for sources of pollution, and to do what can be done to minimize these problems. Using a filter that is rated for mold, virus, and bacteria is important, as is keeping the building clean, relatively dry, and mold-free.