There are other simple sampling methods that may be used to supplement volumetric air sampling. Surface samples are taken by tape lift imprint, by swabbing the suspect surface with a culturette swab, or by submitting a bulk sample of the suspect surface. More: http://www.biowashing.com

1. SURFACE SAMPLING
OVERVIEW

2. There are other simple sampling methods that may be used
to supplement volumetric air sampling. Surface samples are
taken by tape lift imprint, by swabbing the suspect surface
with a culturette swab, or by submitting a bulk sample of the
suspect surface. We typically recommend that a direct
microscopic examination be performed on surface samples.

3. While culturing a surface sample may help resolve a specific
identification problem, used alone such a culture may result in
an inaccurate characterization of the surface sampled. A direct
microscopic examination of a surface shows exactly what is
there, without being affected by an organism’s ability to
compete and grow on sampling media.

5. The primary purpose of a direct microscopic examination of a
surface is to determine whether or not mold is growing on the
surface sampled, and if so, what kinds of molds are present.
Secondarily, most surfaces collect a mix of spores which are
normally present in the environment. At times it is possible to
note a skewing of the normal distribution of spore types, and
also to note “marker” genera which may indicate indoor mold
growth.

6. In addition, when mold growth is present indoors, many
more spores of a particular type will be found trapped on
surfaces. These spores may be in forms which indicate recent
spore release (close proximity), such as spores in chains or
clumps. Marker genera are those spore types which are
present normally in very small numbers, but which multiply
indoors when conditions are favorable for growth.

8. These would include cellulose digestors such asChaetomium,
Stachybotrys, and Torula. While a singleStachybotrys spore is
occasionally seen as part of the normal outdoor flora, finding
5 or 6 of these spores on a single scotch tape slide of a duct
surface is an indicator thatStachybotrys may be growing
indoors.

9. Pros
A direct microscopic examination of a surface shows exactly
what is there, without any skewing by laboratory procedures.
Surface sampling is inexpensive and (for a direct
examination) may be analyzed immediately. Surface sampling
may also reveal indoor reservoirs of spores which have not
yet become airborne.

11. Cons
The presence of biological materials on a particular surface is
not a direct indication of what may be in the air. Health
problems related to indoor microbial growth are generally
caused by the inhalation of substantial numbers of airborne
spores, sometimes over a substantial period of time
(exceptions being, for example, situations involving small
children or immuno-compromised individuals).

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