Indoor Mould Species

Fungal Species

Because different fungal species impact in different ways and to different degrees on human health, prominence should be placed on species identification rather than relying on a crude count of spores captured on a growth medium (colony forming units) (Flannigan, 1994a; Miller et al., 2000). In general, the mycoflora of the indoor air is expected to be similar to that of the outdoor air (Flannigan, 1994a; McGrath et al., 1999). To determine this, comparison of the presence, dominance and/or similarity of airborne fungi indoors to outdoors is critical both to identify, where problems exist inside a building, and to determine the health hazards from species with known health effects (Flannigan, 1994a).

Unfortunately, few studies have reported the types and quantities of fungal taxa present in office and institutional buildings (Godish, 1995) with most studies only reporting genera and few reporting species present (Pasanen, 2001). The studies that have reported the types of fungi present, have found that several fungal genera are present at higher levels in indoor air than in the outdoor air (Solomon, 1985). Examples include the genus Penicillium, which is considered a typical “indoor” fungus group (Bensen et al., 1972) and the genus Aspergillus, which is considered to be one of the most common group of indoor fungi (Bensen et al., 1972).

When the indoors presents a mixture of fungal species that is fundamentally different from the outdoor air, then this represents an altered exposure to fungi when indoors than is normally experienced outdoors. If the lower concentration of fungi in indoor air is a simple matter of filtering out of outdoor air fungi, then this is most likely beneficial to our health. However, if there is an alteration of the species mixture in the indoor air that is due to fungi growing and reproducing indoors, then this may present an unknown but important source of health risk from exposure to fungi.