Moulds (fungi) naturally inhabit indoor environments, such as homes, and office and commercial buildings, and can easily be observed and measured with the use of different monitoring techniques. The source of mould indoors is the outdoor air spora from which airborne mould penetrate indoors via advection and carry-in transfer. Mould spore concentrations in outdoor air reach the levels of over 100,000 spores per cubic metre and depend on season and environmental setting. Fungal spore dispersal from release point may extent hundreds of kilometers and depends on the spore size, release point and prevailing winds.

Mould spores infiltrate the buildings and work environments and thrive indoors. The mould genera most often found in indoor air are those most prevalent outdoors such as: Cladosporium, Aspergillus, Penicillium, Altarnaria. Presence of fungi indoors is normal and unavoidable. In favorable conditions, however, the fungi may proliferate to above-normal levels and may affect building materials, indoor air, and susceptible people. For example, the most common moulds affecting gypsum wallboard are: Penicillium, Chaetomium, Aspergillus, and Stachybotrys atra. People may be affected by a large variety of mould species most often by: Aspergillus, Candida, Penicillium, and yeasts.

The main factors accelerating growth of mould indoors is food and moisture. In buildings, the areas mostly affected by mould include:

•  interior of ventilation systems, where air inflow naturally brings
   in nutrients and fugal spores,

•  carpets where carry-in dust and dirt accumulate at the bottom
   of a carpet pile,

•  unclean food storage areas and garbage deposit rooms.

Exposure to mould may induce adverse health effects in people. Mould inspection and testing is often necessary to identify “problem areas” in a building. All those areas where excessive mould colonization is identified require mould removal or some level of remediation.

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Indoor Moulds (fungi)