Fungal Contamination in Public Buildings: Health Effects and Investigation Methods

3. Investigation of Fungal Contamination of the Non-Industrial Workplace (Continued)

3.4 Methodological Considerations

Microbiological sampling during a building investigation for mold-related problems is complicated. Several cognizant authorities have published guidance on this topic. For example, the AIHA published a Field Guide of consensus methods for microbiological sampling (Dillon et al. 1996). The ACGIH has published a comprehensive manual on microbiological problems of buildings, including chapters on investigation and remediation that recognize the AIHA manual as a source for sampling methods (ACGIH 1999). Details on some of the procedures can also be found in Flannigan, Samson and Miller (Flannigan et al. 2001). The US Environmental Protection Agency (EPA) has also published mold remediation guidance for public buildings (USEPA 2001) and for homes (USEPA 2002).

The goals of any investigation are to establish the cause, nature and extent of fungal contamination and to assess the risk of adverse effects on the health of occupants.

3.4.1 Informed inspection

The first step in investigating a building for microbial contaminants is an informed inspection. This should be performed by someone with engineering or architectural knowledge of moisture problems in buildings, considering the type of building under investigation. The investigation of large public buildings requires a different skill set than a house. Mold contamination can arise from condensation, floods and various types of leaks. Inspection of mold problems requires a thorough knowledge of the design of the building envelope and of the types of failures that result in condensation and water leaks. The physical investigation of molds in both public and domestic buildings requires considerable expertise in the design, construction and operation of these structures. Informed inspection checklists suitable for residential housing have been developed by CMHC (1993) and by Public Works and Government Services Canada (Davidge et al. 1992) and the USEPA (USEPA and USDHHS 1991) for public buildings.

Air sampling is not appropriate unless a thorough building inspection is done either on a concurrent basis or before sampling. Sampling is done to identify contamination that is not visible without destructive testing and to document air contamination. Similarly, after sample results are obtained, the data must be compared with the information obtained during the physical inspections. "Are the results plausible?" is a question that must always be asked and answered to properly assess the risk of false negative and false positive results for mold contamination. Additionally, documentation of the sources and nature of the contamination allows a failure analysis to be done on the building (or HVAC system). This will assist in developing cost-effective investigation strategies and ultimately any remedial action necessary.