How to Report Mold Levels in Mold Test Samples of Surfaces in Buildings InspectAPedia® -
How to report mold levels in buildings
Mold test & reporting procedures
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This article discusses how to report levels of mold in buildings in order to promote consistent use of surface particle mold test adhesive tape
sample descriptive language among microbiology lab and field investigation
professionals. Here we define levels of significance of mold findings in test results. The definitions that follow are a work in progress and need
support by example lab photomicrographs and quantitative study.
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.
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
Our mold level terms "Significant/Dominant, Present, Incidental"
are defined below. Others may use similar terms such as "heavy, medium,
light", or "high, moderate, low. "
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.
Particles Incidental in a
sample means that we found only occasional, or low-levels of fungal
spores in the sample provided-below the level we 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 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.
Type we 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 in measuring toxic or allergenic mold exposure 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.
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.
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
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Mold Exposure Standards: Exposure Standards for Mold, Levels of Severity of Indoor Mold Contamination - Various Published Standards of Permissible Mold Exposure Limits: at what level is toxic or allergenic mold a problem? - What does your "spores per cubic meter of air" or "spore count" really mean - if anything?
MOLD EXPOSURE RISK LEVELS: How to Determine Mold Contamination Probability or Mold Exposure Risk Levels in Buildings Based on Visual Inspection
More Information on Building Diagnostic Inspections and Repairs
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