The analysis of air and surface samples is a critical part of any mold investigation or remediation project. Nevertheless, many practitioners do not realize that analysis of spore trap samples currently is more of an art than a science. The scientific procedures of the analysis process are not very rigid, even for the most basic aspects of the work. With little strict guidance in the industry, the variation in sample results makes it seem as if each lab is offering its own perspective on the data. Much like multiple artists painting the same sunset, the results can be pretty startling when viewed side by side.
To accurately identify spores using light microscopy (i.e., using a regular microscope like those used in school biology classes), the analyst must consider size, shape, texture, septation, attachment scars and color of the objects seen through the lens. With all these characteristics to observe and interpret, it takes time to evaluate some spores, especially smaller types. During the analytical process, the microscopist needs to focus up and down on a particular field of view on the slide and use higher magnification to determine some of these characteristics.
While large fungal spore types are relatively easy to identify and count, small spore types are very difficult and time-consuming to quantify, particularly when there are heavy concentrations on the slide. Misidentification of small spores can occur if all six characteristics are not taken into consideration, leading to erroneous conclusions. For example, smaller round types of Cladosporium, ascospores and basidiospores can be misidentified as Aspergillus/Penicillium-like spores (or vice versa) if an analyst fails to carefully observe distinguishing characteristics due to time constraints or the use of too low a magnification.
Click here to read the complete article, originally printed in the Cleaning & Restoration magazine, published January 2013