•Bacteria-carried by people and animals + soil and plant debris
•Viruses-transmitted by people and animals
•Moulds-grow onwater-damaged materials or wet surfaces
•Pollens-originate from plants
•Animal dander-sources are household pets
•Saliva-mainly cat and rabbit saliva
•Dust mites-grow in damp, warm environments
•Insects-ants, cockroaches, mice, rats, etc.
Humans as a source of biological contaminants
During sneezing from 4 000 to 40 000 small drops of slime and saliva are released into indoor air, which can be the source of bacterial infections
Small parts of skin can trigger asthma
Clothing and bed linen are the source of bacteria and dust mites (for killing of most bacteria the washing temperature should be higher than 85 °C)
Domestic dust contains:
•organic particles (particles of dead insects, plant debris)
•sand (particles of paints, textiles, etc.)
•spores of moulds
•particles of excrements
•dust is a breeding ground for microbes producing mVOC(microbial volatile organic compounds)
Sources of biological contaminants
•During vacuum cleaning of carpets the amount of germs and spores of mouldsAspergillus, Alternaria, Cladosporium, Penicillium, Stachybotrysin indoor air increases 14 times
•Sweeping of floors results in 10 times higher amount of germs
•Mechanical removing of mouldsfrom mouldedsurfaces may induce 3000 times higher amount of spores
•Opening doors to the cellar with mouldedwalls causes 1,5 times higher amount of spores in the living part of the house. Penicilliumspores dominated
•Putting of 6 birch logs into the fireplace is the cause of 100 times greater amount of germs in the indoor air. One hour later the amount of germs was 30 times higher.
•Cleanup of moulded bread or opening of a jar with moulded jam induces 500 times higher amount of spores. 30 min later the amount was 170 times greater. Penicilliumspores dominated.
•Return of a dog or a cat from the walk results in 10 times higher amount of spores. 30 min later the amount decreased to 30 %. Cladosporiumspores dominated.
•Replacement of hamster or rabbit bedding, if they are breededindoors increases the amount of germs in indoor air to 20 000/m 3
•Replacement of the bed sheet causes 3 times higher amount of germs in the bedroom. After 60 min concentration dropped back to the original values.
Symptoms of health problems
•sneezing•watery eyes•coughing•shortness of breath•dizziness•lethargy•fever•digestive problems•allergic reactions•asthma
Alllergic reactions Allergic reactions occur only after repeated exposure to a specific biological allergen. •hypersensitivity pneumonitis•allergic rhinitis•some types of asthma•skin irritation (dermatitis)