El Niño water leaks identify rooms with concealed mould growth and degraded indoor air quality

Residence hall rooms with and without a water leakage history during 1997–1998 El Niño storms were studied in 1999–2001 by destructive inspection (opening) of exterior walls for concealed mould growth and by sampling of room air for culturable fungi. Compared with air in non-leaky rooms and with outdoor air, rooms with 1997–1998 severe water leakages were found to have approximately an order of magnitude increase in levels of airborne Penicillium spp., e.g., P. chrysogenum, P. crustosum and P. aurantiogriseum. The rank order of pooled fungal taxa from leaky rooms was significantly different from the kinds of fungi found in outdoor air. However, the airborne fungi in non-leaky rooms resembled the fungi present in outdoor air. The surface area of visible mould growth concealed in wall cavities of exterior walls was at least 10-fold higher in leaky than in non-leaky rooms. This study showed that inspection for water leaks is of central importance in the evaluation of buildings for mould damage. In addition, the study showed that spores from hidden mould growth could enter rooms in sufficient quantity to significantly affect the rank order profile of taxa in the indoor air.