Application of a fluorometric method for the detection of mold in indoor environments.

Abstract

Mold growth on building materials poses a risk to the health of building occupants. Available guidance from public health and occupational health agencies recognize the need for immediate remediation of mold-affected building materials when the potential for occupant exposure exists, regardless of the species present.(1−3) However, specific guidance on appropriate methods to detect sources of fungal growth have not been provided. Ordinarily, deference has been made to experienced consultants using professional judgment.(2,3) With the absence of validated bioaerosol sampling methods capable of consistently detecting fungal growth in buildings, and the recognition that most methods underestimate actual concentrations in the room air as well as the occupant exposures, investigators often find interpretation of bioaerosol sampling results difficult.(1,4) An air sample may be collected to detect and estimate bioaerosol concentrations or to estimate bioaerosol exposures associated with disturbance of a suspected source, but is not very useful in detecting the presence or absence of fungal growth in a building.(1) Due to the multiple factors involved in bioaerosol release, transport, sample collection, and analysis, the ability to detect sources of fungal growth indoors is often questionable. Nevertheless, many consultants continue to rely primarily on air samples for diagnosis of building environments and clearance of post-remediation sites. A glaring problem with the use of air samples for post-remediation clearance testing is that low bioaerosol concentrations cannot be used to demonstrate the absence of fungal growth sources on building surfaces. Moreover, a positive sample (i.e., one with a high spore count and/or predominance of one mold species) might indicate a mold problem. However, if mold damage is present, it still must be located by visual inspection and surface sampling.(1) Many investigators and researchers have found that, even with massive amounts (>100 square meters) of visible mold growth in buildings or heating, ventilation, and airconditioning (HVAC) systems, air sampling of fungal spores may not reveal the presence of the source.(5) The great variability in fungal spore air concentrations combined with the episodic nature of spore release makes air sampling for fungal spores susceptible to false negative results.(1,4) To test the efficacy of mold remediation (i.e., removal of mold from building surfaces), the best, most reliable, and most highly predictive sample may be a surface sample.