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How to Report Mold Levels on Building Surfaces Using Tape Samples of Indoor Surfaces and Indoor Mold MoldAPedia © Enter your search terms Submit search form   Search This Website - InspectAPedia.com

• How to report level of mold contamination on building surfaces
• Using and reporting on tape samples to check for mold on building surfaces

If collected by an expert during a careful visual inspection, and thus if representative of conditions in a building, surface particle samples collected in buildings provide an important building diagnostic which can be expected to be more reliable than other popular mold testing methods including some which, sadly, may be little more than junk science.

If an indoor particle sample is representative of the area being inspected, then the identity of significant or dominant particles present is important information about conditions in the building. © 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.

Reporting the Level of Mold Contamination on Building Surfaces

When we examine surface test samples collected in buildings, properly obtained by following a visual inspection of the building and by using a clear, consistent sampling procedure, then we can report the following Non-Quantitative Particle or Mold Levels Based on Samples

My mold level terms "Significant/Dominant, Present, Incidental" are defined below. Other labs may use similar terms such as "heavy, medium, light", or "high, moderate, low. "

Depending on where a tape sample is collected, moving the sample source by as little as on inch can completely change both the quantity of mold present (by several orders of magnitude) and actual genera/species detected. Therefore quantitative reporting of mold concentrations found on surfaces (such as Spores/M3 or CFU/M3 on a surface) in buildings should not be attempted except for narrow purposes of scientific research under controlled conditions. The variation in tape and other sampling methods is explored at www.inspect-ny.com/sickhouse/SampMeth.htm.

The purpose of this paper is to seek consistent use of surface particle sample descriptive language among microbiology lab and field investigation professionals. The definitions that follow are a work in progress and need support by example lab photomicrographs and quantitative study.

1. Particles Significant/dominant in a sample means that within the sample these particles were the most-frequent particle in the sample or that the particle was present in most or all sample focal fields under the microscope at 400x or higher magnification.
   
   Problematic mold or allergenic particles listed in this category are likely to be of significance to occupants in the building. Where the particle is a mold genera or species capable of growing indoors a finding at this level makes it likely that there is one (or more) mold reservoir or mold colony in the building.
   
   This term refers to the sample content itself. A visual inspection of the property is needed to determine if the mold is present in extensive or large areas in the building. When the significant/dominant particle(s) present is/are allergenic or toxic mold or an allergen, building investigation to find and clean/remove the problem source is needed
2. Particles Present in a sample means that these particles were frequently present in the sample. They are less likely to be of significance to occupants of the building than "Significant/Dominant" particles except when particles named 1. are particularly allergenic or toxic 2. suggest an undiscovered building problem.
   
   If the building has a history of leaks, water entry, or other hidden moisture problems, the presence of even a few toxic or allergenic spores which are not often found in outdoor air samples may indicate a hidden problem. If control samples from outdoors or from non-complaint areas of a building do not show the presence of these particles, further investigation is in order to determine if there is a significant presence elsewhere in the building than from where this sample was taken.
3. Particles Incidental in a sample means that I found only occasional, or low-levels of fungal spores in the sample provided-below the level I usually find in indoor air samples in buildings where there has been a history of leaks, flooding, or known mold contamination.
   
   This is a positive description of the quality of indoor air insofar as fungal spores are concerned, but one cannot unequivocally conclude that there is no possible health hazard present because: 1. individual exposure, sensitivity, and health status vary widely; 2. even a zero count does not guarantee that a particle is not present in the building. It means only that particle was not in the sample provided.
   
   A careful, expert look at the building may disclose particles that an occupant or inspector was unable to recognize and thus did not send to the laboratory for determination.
4. Particles not detected in a sample means that the particle named was below the detection limit of the inspection, sampling, and examination methods used in the field and laboratory. It does not mean that none of these particles are present in the building.

Types of Mold Level Reporting Errors in Buildings

Type I Errors - missing a problem that's present: Occasional occurrences of certain mold genera in samples might suggest a hidden or un-noticed mold problem in the building somewhere other than at the spot from which the sample was collected. This is particularly true if the sample was collected by someone who is not expert at building science, indoor air quality, mycology, and related disciplines.

Type II Errors - asserting that a problem is present when it is not: Conversely, occasional occurrences of certain mold in samples might also seem to point a problem in a building where in fact none is present. This is a greater risk where mold "counts" are used in air sampling than it surface sampling combined with visual inspection. Occupant indoor air or environment-related complaints or a building history of leaks would suggest that additional investigation is in order.

To avoid both Type I and Type II errors the building consultant needs to understand mycology (e.g. what mold is likely to grow in buildings), the significance of the particles found (e.g. Pen/Asp spore chains vs. individual spores), the history, construction, and materials in the building and the details of the inspection itself when interpreting the importance of low levels of mold in building samples.

Technical Reviewers & References

Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.

• Daniel Friedman - principal author/editor of the InspectAPedia^® Website
• Critique, contributions wanted: Contact Us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.

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