Sampling Methods for Mold
In collecting a mold sample for analysis a number of factors should be taken into consideration:
The objective of the analysis to be done: for e.g. quantifiable analyses if you require mold counts (culturable and spore trap air sampling) and qualitative analyses if presence/absence is required (swabs, bulk and tape).
There are advantages and disadvantages of each sampling method.
Before any sample is submitted to our laboratory, a Chain of Custody has to be downloaded from our website or collected from our offices and presented together with the samples for analysis.
We have outlined some simple methods below to assist you with collecting a representative sample for analysis by our qualified staff members.
For adhesive tape:
Use clear (not frosted) tape.
Remove and discard tape that has been exposed
Remove or dispense enough unexposed adhesive tape to take a surface sample. (2.5 to 5.0 c.m.)
Hold adhesive at edge of one end.
Gently place the tape strip with the adhesive side down on the area to be sampled.
Gently apply pressure along the back side of the tape strip to ensure adhesive is making contact with the surface being sampled.
Remove the tape with a slow and steady force.
Place the tape with the adhesive side down onto a clean microscope slide or into the inside of a re-closable bag
Remove unexposed slide from container
Label the flexible side
Peel off protective cover from the adhesive area
Gently press adhesive area to surface to be sampled.
Gently remove slide from the surface.
Place adhesive slide sample in container. Do not replace protective cover.
Select appropriate swab (dry or wetted)
Remove swab from container and maintain sterility by taking care not to collect any surface, except the area to be sampled.
Run swab across the sampling area in a back and forth motion, both horizontally and vertically, slightly turning the swab with each pass until the entire area is sampled and the maximum material has been collected from the surface.
Return swab to sterile container for transport.
Remove a one or two square inch piece of suspected material and place it inside a clean plastic re-closable bag.
Spore trap (non – culturable) mold:
Identify sampling locations, preferably problem areas and non-problem areas on the inside and an outdoor sample.
Use the following as a guide:
Environmental conditions Recommended sampling time @ 15 liters/min
Wall cavities 1 minute
Dusty, dirty, visible particles in the air 3 minutes
Normal office 5 minutes
Very clean indoor areas 10 minutes
Outside (ambient) 5 minutes
Sampling locations should include problem areas, an indoor non-problem area if available, and at least one representative outdoor area (more are preferred).
Air sampling data represent a specific moment in time and so recording other observations are of great importance. Noting items such as weather, activity levels, HVAC operation, and how accessible the outside air is (e.g. nearby windows and doors to the outside) will be helpful in interpreting the results.
Environmental conditions Recommended sampling time @ 28.3 liters/min
Dusty, dirty, visible particles in the air 1 minute
Normal office 2–3 minutes
Very clean indoor areas 4–5 minutes
Hospital settings Call the laboratory
A variety of media types are available to suit different sampling objectives.
Unless specific fungi are of special concern, the media used should support germination and growth of a wide variety of common fungi.
Media Commonly Used Purpose
Malt Extract Agar (MEA) For isolating a broad-spectrum of indoor and outdoor fungi
Dicholoran-Glycerol Agar (DG-18) For isolating the xerophilic fungi (require low water activity for growth)
Cellulose Agar For isolating cellulose degrading fungi
Prepared by: Ermine Herman
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Mold Culturable Air Sampling: Culturable Air Sampling (Andersen or Biocassette™) https://www.emlab.com/resources/sampling-guides/mold-culturable-air-sampling/: Accessed: October 10, 2018.