Newsletter of the Mycological Society of America Limitations and Considerations in Air Sampling

Limitations and Considerations in Air Sampling, Sample Analysis and Result Interpretation for Airborne Mould Spores by Jackson Kung’u Airborne mould material particularly spores are recognized allergens at normal concentrations to an estimated 20% of the population (Kendrick, 2000). It is not always possible to establish a correlation between mould spore counts in the environment and the presence of allergic symptoms. This has been partly attributed to the use of inadequate air sampling techniques and equipment (Sanchez & Bush, 2001). Mould spores elicit or exacerbate several types of respiratory conditions including allergic rhinitis and asthma. Sensitivity to fungi may develop depending on the individual resistance, amount of spores and the exposure time. Licorish, et al., 1985, demonstrated that inhalation of either Alternaria or Penicillium spores in quantities comparable with those encountered by natural exposure could induce both immediate and late phase asthma in sensitive individuals. Thus, it is important to keep monitoring levels of airborne spore composition and concentration in indoor air. Monitoring of airborne concentration of pathogenic fungal spores has been used over the years in plant pathology to predict disease outbreaks and thus make rational decisions on whether to spray a crop or not. In indoor environment, air monitoring is not common except in hospitals and food and pharmaceutical processing plants. The need to determine airborne spore concentration and composition often arise when occupants complain of ill health. Industrial and occupational hygienists may sample air for airborne fungal spores with the following objectives: (1) to determine the presence of airborne spores, their composition and concentrations in situations where occupants complain of ill health but with no obvious visible mould growth. This information could be used in assessing the possibility of hidden mould growth and human exposure; and (2) to determine if spores had become aerosolised from visible growth sources. The information obtained here could be used as background information in monitoring the effectiveness of remediation measures. Specific objectives may include detection and quantification of certain mould species, for example, in hospital environments, the objective may include detecting the presence of Aspergillus fumigatus, A. flavus and A. niger which are causes of Aspergillosis in immuno-compromised patients. Interpreting and drawing conclusions from results of airborne nonviable and viable fungal analysis can be difficult since there are no agreed occupational exposure limits (OELs) or threshold level values (TLVs) for mould. Despite lack of TLVs, spore traps are invaluable tools in indoor mould investigations. The objective of this article is to point out the limitations of air sampling, sample analysis and interpretations of spore trap results. This information, coupled with professional experience, would enable industrial hygienists and environmental consultants to interpret laboratory results and make rational decisions.