Airborne Fungi in Non-Problem Buildings in a Southern-Hemisphere Mediterranean Climate: Preliminary Study of Natural and Mechanical Ventilation

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There is a growing body of evidence on fungal contami nation in moisture-damaged and complaint buildings worldwide, but little is known about the occurrence and distribution of fungi in healthy non-complaint buildings in a southern-hemisphere climate. The study tested the hypothesis that fungi in healthy buildings are low in numbers and very similar to the numbers and mixtures of species in both the outdoor air and the indoor air in other parts of the world. Fungi were collected using a 6-stage Andersen sampler, and various indoor air quality (IAQ) indicators and a sick-building syndrome (SBS) questionnaire were used in parallel. The results showed that all IAQ parameters were within USA and Canadian guidelines in all the buildings. There was also a low inci dence of SBS complaints and symptoms. The total colo ny-forming unit (CFU) counts were also low, and the range of fungal species was low compared to buildings in other parts of the world. However, the mixture of fun gal genera in the indoor air was different from the out door air. There were also substantial differences be tween indoor locations. At some locations fungi includ ing Aspergillus niger, Penicillium spp. and Alternaria alternata were much higher indoors than outdoors or, as the pathogen Paecilomyces lilacinus, were absent in the outdoor air indicating indoor sources. Differentiation of fungal species was required to identify indoor fungal sources as the outdoor air was not the major source of indoor fungi. The study also demonstrated that evaluat ing the potential exposure to airborne fungi in indoor air requires differentiation to the species level as simple CFU counts could not differentiate between benign and potentially harmful fungi.