CMI Mold Identification & Sampling Techniques 2

Question 1

Which mold genus is most commonly associated with water-damaged gypsum wallboard and appears as a powdery white-to-gray growth?

Accepted Answer

Chaetomium globosum

Answer

Chaetomium globosum is a cellulolytic fungus that colonizes water-damaged gypsum wallboard, producing characteristic white-to-gray powdery growth from its perithecia. Stachybotrys chartarum also grows on wet cellulose but appears as a slimy black colony, not powdery. Ulocladium and Aspergillus versicolor can appear on damp materials but are not the primary genus associated with this specific appearance on gypsum board.

Question 2

When collecting a bulk sample from a suspect mold colony, what is the recommended minimum sample size to ensure adequate laboratory analysis?

Accepted Answer

50–100 mg of material

Answer

A 50–100 mg bulk sample provides sufficient material for laboratory preparation, including culture plating and direct microscopy, without requiring excessive sampling. Smaller amounts like 1–5 mg are often insufficient for reliable extraction and analysis. Larger amounts (200–500 mg or 1 gram) exceed what is necessary and can be unnecessarily destructive to building materials during sampling.

Question 3

A swab sample collected from a non-porous surface such as HVAC coil is best analyzed by which laboratory method?

Accepted Answer

Culture analysis for viable spore count

Answer

Culture analysis grows viable (living) spores on agar media, making it the preferred method for non-porous surfaces like HVAC coils where confirming active biological growth matters. Direct microscopy via tape lift works best on dry porous surfaces and cannot determine viability. ELISA detects specific antigens or mycotoxins, not general spore identification, and X-ray diffraction is used for mineral/crystal analysis, not biological sampling.

Question 4

Air-O-Cell cassettes used in spore trap sampling capture particles in what approximate size range that is most relevant to fungal spores?

Accepted Answer

1–100 microns

Answer

Air-O-Cell spore trap cassettes are designed to capture particles in the 1–100 micron range, which encompasses the vast majority of fungal spores found in indoor environments. Sub-micron particles (0.1–0.5 µm) are too small to be fungal spores and represent bacteria or ultrafine particles. Particles above 200 µm are too large to remain airborne for sampling and fall out quickly due to gravity.

Question 5

When performing a visual inspection, which condition is the strongest indicator that Stachybotrys chartarum may be present?

Accepted Answer

Chronically wet cellulose material with black slimy growth

Answer

Stachybotrys chartarum requires chronically wet cellulose-based materials (such as paper-faced drywall or ceiling tiles) and produces a characteristic slimy black growth due to its mucilaginous spore heads. Dry dusty surfaces cannot support Stachy growth as it requires very high, sustained moisture. Yellow staining on vinyl and white efflorescence on concrete are abiotic (non-biological) processes unrelated to Stachybotrys.

(CMI) Certified Mold Inspector Practice Test

(CMI) Certified Mold Inspector Practice Test

CMI Mold Identification & Sampling Techniques 2