Air Sampling For Mold

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Mold Sampling IAQS
Mold Air Sampling

The American Industrial Hygiene Association recommends mold sampling when the source of contamination is unclear, if a disease associated with a mold is suspected, if litigation is involved and for clearance purposes associated with a remediation in order to ascertain that mold readings are at natural background levels or at a Normal Fungal Ecology.

Even when sampling is performed, it's not possible to correlate results with an individual’s symptoms because everyone reacts differently to different levels of molds and allergens. This is called a dose response relationship.

Air samples fall into two general categories (Viable & Non-Viable). The first type Viable uses a culture medium of some sort to collect the airborne spores. The spores are allowed to grow and the resulting colonies are counted and identified. Each growth area seen on the plate is known as a colony forming unit (cfu). Since the amount of air drawn through the sampler is carefully documented and the areas of fungi growth on these ample precisely counted, a conversion factor can be used to calculate the number of cfus per cubic meter of air (cfu.m3).


Viable Culture samples have advantages and disadvantages. An advantage is that counting and identifying the colonies that grow can be done in such away as to identify both the genus and the species of the organism. On the other hand, these samples do not include non-viable spores, even though such spores can still cause health problems. Culture samples take several days for the mold to grow, so there can be no rush turnaround time.
The other general category of air samples are Non-Viable collected using an Air Sampling cassette. The air sampling cassette is a sampling device designed for the rapid collection and analysis of a wide range of airborne aerosols. These include fungal spores, pollen, insect parts, skin cell fragments, fibers, and inorganic particulates. Air enters the cassette, the particles become impacted on the sampling substrate, and the air leaves through the exit orifice. The airflow and patented cassette housing is designed in such a way that the particles are distributed and deposited equally on a special glass slide contained in the cassette housing called the ``trace."
The slide is then analyzed under a microscope . Any spores observed are identified and counted, and then a conversion factor is used to calculate the number of spores per cubic meter of air. This method includes both viable and non-viable spores, so it can be a more accurate indication of airborne spore levels. The analysis can be performed immediately after the sample is taken, so rush turnaround time is possible.
However, direct microscopy is usually limited to designation of mold at the genus level and generally cannot be used for bacteria. Water samples are taken to determine the presence of bacteria, such Legionella and E.coli. The samples also detect bacterial toxins, such as endotoxins.