Sterile swabs are ideal for testing the level of contamination on surfaces. Swabs are very useful on hard-to-reach places such as crevices or on wet surfaces where cellophane tape cannot be used. Both mold and bacteria can be tested by culture methods from a single swab. It is recommended that wet swabs are used on dry surfaces and dry swabs on wet surfaces. Wet culture medium swabs are required for bacterial sampling.
Objective of Surface Sampling (Tape, Swab, or Bulk)
To determine whether visible stain or discoloration on a surface sampled is indicative of mold growth.
To determine the type of molds actually growing on the surface sampled
Advantages and Disadvantages
Surface sampling for direct microscopic examination is inexpensive and may be analyzed immediately.
A direct microscopic examination of a surface shows exactly what is there.
Surface sampling may also reveal indoor reservoirs of spores that have not yet become airborne.
The presence of biological materials (spores, hyphal frogments, insect parts, etc) on a particular surface is not a direct
indication of what may be in the air yet health problems related to indoor biological contamination are generally caused by the
inhalation of substantial amount of airborne particulates, sometimes over a substantial period of time.