I. Air Sampling - Viable
Viable sampling is used to determine airborne concentrations of mould and bacteria that are living and can grow on media. The Anderson N6 or Aerotech 6 single stage bioaerosol samplers are 2 samplers available for rental to perform this type of sampling.  In such sampling, air is drawn at high velocity through a multiholed orifice plate where inertial forces cause the impaction of the airborne particles onto a nutrient agar surface.  The selection of agar depends on the sampling objective and the incubation temperature of the agar depends upon the microbial under investigation.  Once the media is selected and the incubation temperature is determined, the colonies are allowed to grow.  As they mature, they are quantified and identified to the genus level for fungal and bacterial isolates and speciated when possible.  The concentrations are expressed as colony forming units per cubic meter (CFU/).

A few guidelines when viable air-sampling:
Samples should be collected for complaint and noncompliant areas. Sampling procedures should include a representative outdoor to provide a reference for determining whether certain genera and species are being amplified in the indoor environment. Sampling durations of 1-2 minutes, 28.3-56.6 total liters, are commonly used.  Areas with visible fungal growth may be sampled for a lesser time and likewise, remediated areas may be sampled for a longer duration. A sufficient number of blanks or control samples should be submitted to establish the quality of the data collected.

Duplicate samples are recommended for each culture used at each location to characterize exposures at individual test sites.

II. Air Sampling – Non-Viable
Total spore/particle sampling methods are used to evaluate the presence of viable and non-viable mould spores, hyphal fragments and pollen. In commercially particle sampling devices such as the Zefon Mini Pump, particles are drawn through a tapered slitted orifice and impacted on an adhesive-covered cover slip.  The cover slip is mounted on a microscope slide with stain and examined at 400x and 600x magnification. Both spores and hyphal fragments are counted on a fraction of the collection surface (5%) using horizontal traverses.  The count is then converted to a concentration based on volume of air sampled and expressed as spores or structures per cubic meter.  (CTS/).

A few guidelines when non-viable air sampling:
Samples should be collected for complaint and noncompliant areas.
Sampling procedures should include a representative outdoor to provide a reference for determining whether certain genera and species are being amplified in the indoor environment.
Flow rates recommended for total mould spore sampling are in the range of 10-15L/min.
Seventy-five total liters is recommended as a benchmark for representative sample volume.
In dusty or heavily polluted areas, particle overloading may occur, and sampling times/volume should be adjusted accordingly.

III. Bulk Sampling
Bulk sampling provides information regarding whether environmental materials may be contaminated beyond background levels and possibly serve as sources of biological agents that may be disseminated as bioaerosols. Bulk sampling is conducted on mould-infested materials to identify mould and/or bacteria types as well as their relative abundance. 

Bulk samples are cut or otherwise aseptically removed from a source and placed in a sterile container.  A segment of the sample is selected from an area that is least likely to have been handled and most likely to recover representative microbials.  The selected sample segment is weighed and dispersed in a sterile liquid, diluted as necessary and inoculated on nutrient agar media.  The selection of agar depends on the sampling objective and the incubation temperature of the agar depends upon the microbial under investigation.  Once the media is selected and the incubation temperature determined, the fungal and bacterial colonies are allowed to grow. As colonies mature, they are quantified and identified to the genus level and speciated when possible.  The concentrations are expressed in terms of colony forming units per gram of material (CFU/g).

A few guidelines when bulk sampling:
As a rule of thumb, aseptic techniques should be strictly adhered.
Bulk samples should be delivered to the laboratory as soon as possible and protected from temperature extremes during transport.
Bulk samples should include a representative cross section of the area sampled.

IV. Dust Sampling
Dust sampling provides information about possible sources of biological agents in buildings as well as the composition and relative concentration.  Dust, house duct, or settled dust are terms used to describe the material that collects on horizontal surfaces in textiles, upholstered furniture and carpets.
Dust samples can be collected using a suction device, filter for full size vacuum cleaner, or particle sampling devices fitted with specially designed filters.  The dust sample is weighed and dispersed in a sterile liquid, diluted as necessary and inoculated on nutrient agar media.  The selection of agar depends on the sampling objective and the incubation temperature of the agar depends upon the microbial under investigation.  Once the media is selected and the incubation temperature determined, the fungal and bacterial colonies are allowed to grow.  As colonies mature, they are quantified and identified to the genus level and speciated when possible.  The concentrations are expressed in terms of colony forming units per gram of material (CFU/g) or colony forming units per area sampled (CFU/g/units of area sampled).

V. Swab - Surface Sampling
Surface samples provide information similar to that obtained by bulk samples regarding whether environmental materials may be contaminated beyond background levels and possibly serves as sources of biological agents that may be disseminated as bioaerosols.  Often, surface sampling is preferred over bulk sampling when a less destructive method of sample collection is desired. Surface samples are collected by washing, rubbing, or brushing a swab over a prescribed area.  Swab samples are suspended in liquid and diluted as necessary.  Aliquots of the sample are inoculated on nutrient agar media.  The selection of agar depends on the sampling objective and the incubation temperature of the agar depends upon the microbial under investigation.  Once the media is selected and the incubation temperature is determined, the colonies are allowed to grow.  As they mature, they are quantified and identified to the genus level for fungal and bacterial isolates and speciated when possible.  The concentrations are expressed in terms of colony forming units per swab or colony forming units per area sampled.

A few guidelines when swab surface sampling:
Aseptic techniques must strictly applied.
Prior to collection, swabs should be wetted with sterile water to enhance particle collection.
Swabs should be delivered to the laboratory as soon as possible and protected from temperature extremes during transport.

VI. Tape – Surface Sampling
Transparent tape or Biotape samples of infested buildings provide a quick and easy method to identify the presence of major fungal general.

A small piece of transparent tape is touched or pressed to a prescribed or infested area and affixed to a microscope slide containing a drop of stain.  The slide is examined at 600x magnification and the fungal spores, elements and hyphal fragments are identified and quantified.
A few guidelines when tape sampling:
One to 2 inches of crystal clear transparent tape should be used and fixed to a slide.
Tape should not be wrinkled, overlapped or torn.

A few guidelines when swab surface sampling;
Aseptic techniques must be strictly applied. Prior to collection, swabs should be wetted with sterile water to enhance partical collection. A measured area should always be swabbed when a culture is ordered. This way, th elab can provide a report in units of CFU per metered area. Otherwise, the results will be difficult to interpret and will be reported as CFU/swab, a fairly meaningless unit. An area of between 1 and 4 square inches is recommended. Please notate the actual area collected for each sample, on the lab test request form. Swabs should be delivered to the laboratory as soon as possible and protected from temperature extremes during transport.