Aspergillus has close to 200 species and varieties. This mould is widely distributed from the arctic region to the tropics and is frequently found in air, soil, and stored agricultural products. It’s also very common in damp basements.
Harmful effects of Aspergillus to our lives
Species of Aspergillus produce dry, hydrophobic spores that are easily inhaled. Inhaling spores of Aspergillus, particularly those of Aspergillus flavus and Aspergillus fumigatus frequently cause pulmonary aspergillosis, either allergic, or invasive or a combination of the two. A. flavus produces the highly potent mycotoxin called aflatoxin which over the years has been reported as the cause of death in humans and animals. In 2004 aflatoxin killed over 100 people in an East African country who consumed grains infested by A. flavus. Many other species of Aspergillus such as A. clavatus, A. niger, and A. versicolor are also known to be toxigenic or allergenic. Instant action is required when growth of these moulds appear in occupied indoor environment.
Because of their ability to produce a large number of enzymes, species of Aspergillus are capable of utilizing an enormous variety of organic material for food. Therefore, under humid conditions, it will grow on leather, cloth fabrics and books reducing their value and imparting musty odour to these items. Several species are frequently found on grains and exposed foodstuffs where they cause decay and subsequent loss of food.
Occurrence of Aspergillus species in indoor environment
Species of Aspergillus have been isolated from damp walls, wallpaper, PVC/paper wall covering, gypsum board, floor, carpet and mattress dust, upholstered-furniture dust , acrylic paint, UFFI, leather, HVAC insulations, filters and fans, humidifier water, shoes, leather, bird droppings, potted plant soil, plastic and decomposing wood.
Aspergillus fumigatus is frequently found in kitchens and bathrooms while in mattresses and carpets, Aspergillus versicolor and Aspergillus repens are common. A. versicolor and A. fumigatus are also common in basements. Species frequently found in flower pot soil are A. fumigatus, Aspergillus niger and Aspergillus flavus.
Generally the amount of airborne spores of Aspergillus spp. in indoor air is higher than outdoors at any given time. In the home, the amount of airborne spores is significantly increased when cleaning is carried out mechanically, for example, when carpets are vacuum cleaned.
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