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Here we discuss the advantages and shortcomings of using adhesive tape to collect mold test samples (or other dust or particle samples) from indoor surfaces. In this article series we discuss the validity of nearly all of the popular mold testing methods currently in use, pointing out the strengths and weakness of each approach to mold sampling in the indoor environment. This study presents a summary and critique of some popular methods used to examine indoor air quality to test for presence or absence of problematic levels of toxic or allergenic mold or other bioaerosols. Our page top photo demonstrates that the tape sampling location is critical for accurate identification of particles or mold types in a building - each of the three tapes in this photograph collected an entirely different genera/species of mold.

We describe and critique specific "testing" or "sampling" methods used to "test" buildings for mold in the course of a building investigation. The appropriateness of testing at all is discussed on this and other pages at our website. Because mold test validity and mold test accuracy are often confused, readers should also see ACCURACY OF VARIOUS MOLD TEST METHODS. People who need to conduct mold inspection and testing indoors should see MOLD TEST PROCEDURES and TECHNICAL & LAB PROCEDURES.

Our MOLD INFORMATION CENTER includes more broad discussions of the overall approach to building investigation, as do many expert references cited at that web. For a more comprehensive collection information about mold test methods see INDOOR AIR QUALITY METHODS COMPARED. For more on "mold classes" (Cosmetic mold vs. allergenic mold vs. toxic or pathogenic mold) see MOLD CLASSES, HAZARD LEVELS and more references such as a Mold Action Guide are at the end of this document.

© Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Recommendations for Using Tape sampling for Testing Buildings for Toxic Black (or other) Mold

15th Annual North Carolina/South Carolina
Environmental Information Association Technical Conference
Myrtle Beach, SC
Daniel Friedman 23 September 2005, Updated 4/14/2009

Clear cellophane tape is pressed into a sampled surface, then removed and affixed to a clean surface such as a plastic bag or a microscope slide for mailing to a lab. The lab prepares the tape for microscopic examination. For mold genera and species identification the tape is examined in the laboratory. Tape samples can also be cultured (see Culture discussion below). This is the least-expensive collection method available, and is a preferred tool.

See MOLD TEST KITS for DIY MOLD TESTS for a detailed procedure using this particle sampling method.

Using clear adhesive tape pressed into a surface to be tested is the first choice recommended method for identifying mold in a building, particularly when combined with visual inspection as part of a mold investigation, per AIHA and other expert sources. This method permits rapid identification of genera (family name) and very often species (individual member name), particularly when the mold sampled has uniquely-identifiable spores or where the sample collects the conidiophore or spore-producing body as well.

In some cases genera determination alone is quite sufficient as the some of the common problem-genera (Penicillium sp. and Aspergillus sp.) do not have non-problematic members which grow in buildings. Speciation is more likely to be needed when doing medical diagnosis. Tape samples can also be cultured if additional speciation is needed. Since tapes can collect the conidiophores and hyphae (when tape spot is chosen with some thought) they give more data than an air or vacuum sample.

For building where large amounts of mold are found or suspected, tape sampling is a qualitative approach which is usually quite successful in addressing the basic question: is there a problematic genera which requires professional remediation? Combined with a visual inspection to locate target areas of risk and to find visible problems, it is the most essential component of a building mold investigation and is the method recommended by experts writing in the field and by the AIHA's own training materials.

Tape samples are the preferred method of collecting surface samples in buildings. Tape pressed into appropriate portions of suspected mold growing on a surface collects the most material from the surface and often includes sufficient structural material to identify the dominant problematic genera and species present.

A properly collected sample is likely to contain both fungal conidia, conidiophores, and hyphae, the latter two of which are important aids for speciation. Tape samples of building dust and even tape samples of moldy carpet are also generally useful in this manner but have some limitations discussed below.

A Guide to Using Tape Sampling for Determination of Mold genera and mold species:

Nearly all building mold genera can be determined by light microscopic examination of tape samples. In the majority of building investigation cases the key question is "is there a problematic genera (toxic or allergenic) requiring containment and professional remediation?" This can almost always be completely answered from genera alone. This is because within the more common troublemakers, their non-problematic member species may not occur in buildings. For example, Penicillium notatum, used for the drug penicillin, does not grow in buildings! If you find Penicillium sp. in a building in quantity it needs to be remediated.

Speciation of many mold genera can also be determined from tape sample material alone in many but certainly not 100% of cases. Some examples of easily speciated molds from among the most common genera and species found in buildings: Cladosporium sphaerospermum, C. cladosporioides, Ulocladium chartarum, Taeoniella rudus, Pithomyces chartarum, Stachybotrys chartarum, Chaetomium globosum, Chaetomium aureum, Aspergillus niger are just a few examples.

Our photo (left) shows a nicely preserved conidiophore of Aspergillus niger on an adhesive tape sample.

A good mold tape sample which collects the conidiophore and hyphae makes speciation possible for many molds. Many other airborne spores appear in buildings and can be similarly speciated, but are not building molds. Other airborne molds such as the Aspergillus and Penicillium families are probably a sufficient hazard in buildings that if they are present in a large reservoir, speciation is not needed to decide to remediate.

Shortcomings of tape sampling tests for Toxic Mold:

1. Everything depends on where you stick the tape. Investigators and ordinary building occupants tend to collect that which is easy to see - "black mold" and may miss more important, more health-risky light-colored and highly airborne genera (Aspergillus, Penicillium) which are also present but more difficult to see. An expert looks for mold-suspect material that seems to represent the dominant presence in an area by color, texture, and growing surface material. It would be unusual for there to be only a single genera/species of mold in a mold-problem building. Looking and taping requires some guidance and education.
   
   
2. Some smaller airborne mold spores do not settle out of air rapidly and might appear equally as plated-out on walls as in dust on horizontal surfaces. In building inspection to search for an unidentified problem source, samples of surface dust may under-represent the presence of these molds, though where a substantial airborne presence exists we have always found a surface dust presence as well. By contrast, properly collected tape samples from visible mold growing on a surface does not suffer this shortcoming.
   
   
3. Speciation of genera may be needed for special medical diagnostic reasons. From spores alone in any sample method, two of the most widespread problematic genera can be speciated only to a few cases. (Aspergillus niger for example.) Therefore for medical use, tape speciation of some genera is too limited, in particular if the sample collects only spores - a problem which can occur if tape is pressed into dust rather than into an area of growing mold, or when tape of a mold colony is pressed into a spore-packed center of a mature colony instead at the edges where the new colony growth and conidiophores are easier to find. A little knowledge of mycology is useful to professional building inspectors.
   
   
4. When growing conditions become unfavorable some molds change form into an encysted or encapsulated dormant state, forming fungal perithecia, cleistothecia, or pycnidia which may be collected as "black stuff" from building surfaces (particularly wood). While often one finds identifiable material among perithecia that cant' be assured. Culturing of such samples may produce an identifiable fungus if by luck the right culture media is selected.
   
   
5. Tape sampling is qualitative, not quantitative. Most experts and competent labs will offer a description of the density of fungal material found in the sample using non-standardized terms like Level 1-2-3-4 or Light, Medium, Heavy, or Dominant, Present, and Incidental. These terms lack a standard definition but are of some use provided the lab has and can provide their own standard and definition.
   

In sum, the determination of the presence of a building mold problem (toxic or allergenic) vs. cosmetic mold can usually be made from tape samples alone. Tape samples are preferred by the most experienced and trained professionals in the aerobiology field.

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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

MOLD TESTING METHOD VALIDITY
Introduction
  Air samples
    Shortcomings of air sampling
    Mold in Air: Quantitative Analysis
  Tape sampling for mold
    Determination of mold genera
    Determination of mold species
    Shortcomings of tape sampling
  Vacuum samples
    Surface vacuuming
    Shortcomings of surface and carpet vacuuming
    Vacuuming building cavities
    Vacuuming exposed insulation
    Shortcomings of vacuuming insulation
  Cultures to "Test for Mold"
    Shortcomings of culturing
  Swab sampling
  Shortcomings of swab sampling
  PCR methods for Mold Identification
  Mold "Testing" vs. Mold "Problem Identification"
  Are Mold Test Kits Useful?
  Reasons to Test for or Identify Mold
    1. Save Money if it's Just Cosmetic Mold
    2. Mold Related Illness
    3. Mold Cleanup Data baseline

• Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. (727) 595-4211 mark@BestTampaInspector.com

For more information on tape sampling methods see

MOLD TESTING USING ADHESIVE TAPE
  What is Tape Sampling
  How Do we collect a Tape Sample
  Comprehensive Discussion of mold testing methods
MOLD TEST KITS for DIY MOLD TESTS how to collect and send a tape sample to a laboratory
SAMPLING DRYWALL how to choose the sampling location when using adhesive tape.

Also see

• Spore Counting Methods and Validity
• Mold Testing: Air samples and their interpretation - a quick tutorial
• Mold Levels - how much is bad?
• Mold Levels in Mold Test Samples of Surfaces in Buildings

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• Books, Complete List of Environmental Inspection, Diagnosis, Cleanup, Air Quality & Design, Inspection, Repair Books at the InspectAPedia Bookstore
• Environmental Health & Investigation Bibliography - our own technical library on indoor air quality inspection, testing, laboratory procedures, forensic microscopy, etc.
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