Biological Pollutants

Biological pollutants

Biological Pollutants


Biological pollutants can be a problem in your home, causing considerable health problems! They include bacteria, viruses, animal dander, cat saliva, house dust, mites, cockroaches and pollen.

Sources of biological pollutants can be reduced by controlling the humidity level in your home. Therefore, the relative humidity should be kept between 30-50 percent. Significantly, standing water, water-damaged materials or wet surfaces serve as breeding ground for moulds, mildews, bacteria and insects. Furthermore, house dust mites, the source of one of the most powerful biological allergens, grow in damp, warm environments.

Biological Pollutants are:

  • Pollens, from plants.
  • Viruses transmitted by people and animals.
  • Mould.
  • Bacteria carried by people, animals, and soil and plant debris.
  • Household pets, which are sources of saliva and animal dander (skin flakes)
  • Droppings and body parts from cockroaches, birds, rodents and other pests or insects.
  • The protein in urine from rats and mice is a potent allergen. When it dries, it becomes airborne.
  • Contaminated central air handling systems can become breeding grounds for mould, mildew and other sources of biological contaminants.

Many of these biological contaminants are inhaled.

Biological pollution is often found in locations that facilitate its growth, e.g. moisture, water etc. These include:

    • Damp or wet areas, e.g. cooling coils, humidifiers, condensate pans or unvented bathrooms facilitate mould growth.
    • Draperies, bedding, carpet and other areas where dust collects facilitates the growth of biological pollutants.

Health Effects of Biological Pollution

Some biological pollutants trigger allergic reactions, including:

  • Hypersensitivity pneumonitis.
  • Allergic rhinitis.
  • Some types of asthma.

Moulds and mildews release disease-causing toxins. Symptoms of biological pollutants include:

  • sneezing,
  • watery eyes,
  • coughing,
  • shortness of breath,
  • dizziness,
  • lethargy,
  • fever,
  • and digestive problems,

Allergic reactions occur only after repeated exposure to a specific biological allergen. In addition, the reaction may occur immediately on re-exposure. Therefore, if you have mild allergic reactions or no reactions at all, this may suddenly change to highly sensitive to particular allergens.

Humidifier fever is the exposure to toxins from microorganisms that can grow in large building ventilation systems. In addition, humidifier fever can also occur in home heating and cooling systems, and humidifiers.

Children, elderly people and people with breathing problems, allergies, and lung disease are particularly susceptible to disease-causing biological agents.

Reducing Exposure

Good housekeeping and maintenance of heating and air conditioning equipment are imperative. Furthermore, adequate ventilation and good air distribution are important.

The key to mould control is moisture control. If mould is a problem, clean up the mould and get rid of excess water or moisture. In addition, maintain relative humidity between 30% – 60%, to help control mould, dust mites and cockroaches.


  • Use exhaust fans to vent kitchens and bathrooms. Especially vent clothes dryers outdoors.  Consequently, this will reduce the moisture build-up from everyday activities.
  • Ventilate ceiling space to prevent moisture build-up. Keeping humidity levels in these areas below 50 percent can prevent water condensation on building materials.


  • If using cool mist or ultrasonic humidifiers, clean appliances according to manufacturer’s instructions and also refill with fresh water daily. In addition, clean evaporation trays in air conditioners, dehumidifiers and refrigerators frequently.
  • Thoroughly clean and dry water-damaged carpets and building materials. However, replacement may be preferable. Furthermore, it is difficult to completely rid carpets of and building materials of biological pollutants.

Dust Control

  • Keep the house clean! Obviously, regular cleaning will reduce house dust mites, pollens, animal dander and other allergy-causing agents.
  • If you are allergic you may choose to use allergen-proof mattress encasements.
  • Wash bedding in hot (50°C) water and also avoid room furnishings that accumulate dust.

Vacuuming can increase airborne levels of mite allergens and other biological pollutants. Finally, using vacuums with high-efficiency filters may help.

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