Mould spores are tiny structures produced by moulds for the purpose of propagation. The term spore is general. There specific terms used for spores depending on how they are produced or the group of fungi producing them. Ascospores for example are spores produced by a group of fungi called Ascomycetes while Basidiospores are spores produced by Basidiomycetes which include the mushrooms.

How would spores affect human health?
Spores are tiny (range between 2-100 micrometers) and therefore are easily inhaled into the lungs. Susceptible individuals react to the protein component of the cell wall of the spores. Some moulds such as Aspergillus fumigatus may also grow in the lungs causing what is referred to as Aspergillosis.

How would you tell if you are inhaling potentially harmful levels of spore concentration?
The way to tell if occupants of a building were inhaling potentially harmful levels of spore concentration is to take air samples. Air may be taken to be analysed by culture methods or by direct microscopic examination. Culture methods may significantly underestimate the total airborne mould concentration in the air because only the viable spores or fragments of the mould can be detected in culture. The spores/fragments may also not be detected if the media used for culturing were not suitable for the types of moulds present in the air. Samples taken for direct microscopic examination (also referred to as non-viable air samples) allow the analyst to count all the spores and fragments regardless of whether the spores were viable or dead. Since susceptible individuals can also react to dead spores, non-viable samples would be the best to give an idea of whether occupants were inhaling potentially hazardous levels of mould spores.

The pictures show spores trapped from highly contaminated indoor air. The first picture shows spores of Chaetomium and Aspergillus/Penicillium. The second photo shows Ulocladium spores and Stachybotrys spores. Chaetomium, Stachybotrys and Ulocladium species are indicators of serious water damage. Spores of these moulds and those of Aspergillus and Penicillium pose inhalation risk.

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