Airborne microorganisms sampling methods

In active monitoring, air sampling instruments bring a specific volume of air into a collection vessel. The main methods that are used for sampling and quantification of viable airborne microorganisms are impaction on solid surface, filtration, centrifugation, cyclones, electrostatic precipitation, and the impingement in liquids (Table 4). 

It should also be mentioned that the majority of microbial airborne particles are dead or noncultivable , which means that they do not grow under the laboratory conditions chosen. This is, for example, true for microorganisms hke Stachybotrys chartarum. To fully survey the indoor microbial situation and to avoid overlooking fungal species which may be indicators of damage, additional samples have to be taken using methods hke direct microscopy which are not dependent on hving, cultivable cultures. Here, for example, microscopic slides with an adhesive surface are inserted in special impactor samplers. The airborne particles collected are stained in the laboratory. EspeciaUy spores with a characteristic shape hke those of S. chartarum are easily detected under the microscope. 

Bioaerosols can be sampled by allowing them to settle directly onto culture plates, a simple, inexpensive method that allows one to determine the presence of a specific microorganism. The technique, however, is not useful for quantifying airborne concentrations because, after culturing, the size of the initial particle cannot be determined, so TS and the flux are not known. 

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