Fast, Affordable Mold Testing

Sampling Overview and Interpretations

Sample	Target	Type	Quantification	Equipment
Air-o-cell	air	non-cultured	spores/m3	sampling pump + Air-o-cell cassettes
Allergenco	air	non-cultured	spores/m3	Allergenco sampler + greased slides
Andersen	air	cultured	CFU/m3	Andersen sampler + petri dishes
Bulk(a)	bulk\dust	cultured(a)	CFU/g (b)	none
Swab(a)	bulk\dust	cultured(a)	CFU/m2 (c)	sterile swab (Q-tip or cotton ball will work)
Tape-lift	bulk\dust	non-cultured	semi-(d)	clear sticky tape (scotch, etc...)

 

(a) Bulk and Swab samples can be tape-lifted for direct examination
(b) Quantification of cultured Bulk sample requires that more than 1 gram of sample be provided
(c) Quantification of cultured Swab sample requires that the area sampled (9 cm2, 1 square inch, etc...) be measured and provided
(d) Not for true quantification, but a semi-quantitative rating is provided (trace, minor, major, abundant)

Notes

Non-cultured	- viable and non-viable spores (and other particulate) directly examined under a microscope
Cultured	- viable spores are grown in a petri dish for several days before identification
CFU	- colony forming unit

 

General

Non-cultured samples involve direct exam and identification of individual spores. Some mold types such as Aspergillus and Penicillium are not distinguishable by their spores alone, so for non-cultured samples some molds have to be grouped together like Aspergillus\Penicillium. Direct exams do not require any growing time, so rush or same day results are available at additional cost.

Cultured samples are grown in a petri dish for several days before analysis, and the entire colony, not just the spore, is utilized for the identification. This enables better or more exacting identification of certain mold types, but certain molds don’t grow at all in standard culture media or will grow very slowly. Additionally, dead spores will not grow at all even though these spores can have the same health effects as viable spores. Rush results are not available because cultures require a certain amount of time to grow (7-10 days, which can vary from sample to sample.)

Stachybotrys in particular does not grow well in standard culture media, and direct examination is the preferred method of identification (airocell/allergenco or tape). If you are specifically testing for Stachybotrys using a cultured method, then other media types such as Rose Bengal might be preferred or requested instead of Malt Extract Agar.

Gravity plates (commonly found in "home test kits") are not generally used by professionals

AIR-O-CELL SAMPLES
ALLERGENCO SAMPLES

Air-o-cell and Allergenco samples require specialized equipment. This type of sample is a non-cultured air sample. Results are reported in concentrations of spores per cubic meter (spores/m3). This test is referred to as a "snapshot" of the air at the exact time of sampling. Results account for both alive and dead spores as well as pollen, skin, insect parts etc. (if a full profile analysis is requested). It is important to note that allergic reactions can come from dead spores and alive spores alike. In addition, the toxins that some fungal spores produce remain toxic after the spore itself has died. Air-o-cells can also be used to test inside a wall cavity (by removing a light switch panel or other opening. Usually only 15 to 30 liters is the most one can sample before completely overloading the sample with drywall dust.) Normal laboratory turnaround time is usually several days, but rush or same day results are available for additional cost.

Interpretation of Results

The general guideline to follow is that the concentration and types of spores in the inside sample should be similar to or lower than the concentration and types of spores found in the out of doors sample. Do to the high variability in results; this test is mainly useful as a "check" to alert one to potential problems that might have been missed by visual inspection. Accurate measurements of true airborne concentrations require multiple samples taken during different times, and it can involve complex statistical analysis. The category Aspergillus / Penicillium are small (1-3 microns), round, colorless spores that may include: Gliocladium, Trichoderma, other morphologically consistent with Aspergillus / Penicillium types. A culture sample would be necessary to differentiate between them. Currently there are no dose response relationship statistics for allowable or safe levels of aeroallergens. However if spores of Aspergillus / Penicillium are found at higher levels than outside, or Stachybotrys are found inside at even low concentrations, further investigation of the source should be conducted and evaluated by a professional. For information about types of molds found on the lab report, please see glossary page.

How to sample

• What you need: Air-o-cell = a high volume pump (15Lpm) and Air-o-cell cassettes
• Allergenco = Allergenco sampling unit, greased slides and slide protector box

Air-o-cell Sampling Procedure:

1. Calibrate pump to 15 LPM
2. Open round end of cassette and attach to pump
3. Open square end of cassette
4. Sample for 5 to 10 minutes at 15 LPM; sample inside complaint area, non-complaint area, and out of doors.
5. Wall cavity samples should be run for only 1 to 2 minutes.
6. Replace stickers on both ends of cassettes and label the samples with a sample number and location and volume.

Allergenco Sampling Procedure: please refer to owner’s manual supplied by the manufacturer

ANDERSEN SAMPLES

Andersen samples require specialized equipment. This type of sample is a cultured air sample grown in the laboratory on Malt Extract Agar or other media. Results are reported in concentrations of CFU’s per cubic meter (CFU/m3). Results indicate the number of viable (alive) spores in the air at the time of sampling. Cultured samples such as this allow better differentiation of certain mold types such as Aspergillus and Penicillium because once growth occurs; you are identifying colonies rather than just individual spores. On the other hand, certain molds do not grow or compete well on standard culture media. Analysis does not and cannot include counts for dead spores, pollen, skin, insect parts, etc. It is important to note that allergic reactions can come from dead spores as well as live spores. In addition, the toxins that some fungal spores produce remain toxic after the spore itself has died. Normal laboratory turnaround time is 7 to 10 days (cultures require time to grow and it is impossible to provide rush service.)

Interpretation of Results

The general guideline to follow is that the concentration and types of colonies found in the inside sample should be similar to or lower than the concentration and types of colonies found in the out of doors sample. Do to the high variability in results; this test is mainly useful as a "check" to alert one to potential problems that might have been missed by visual inspection. Accurate measurements of true airborne concentrations require multiple samples taken during different times, and it can involve complex statistical analysis. Currently there are no dose response relationship statistics for allowable or safe levels of aeroallergens. Please note that Stachybotrys does not grow well on most laboratory media and an absence of Stachybotrys on a culturable sample report should not rule out this type of mold. For information about types of molds found on lab report, please see glossary page.

How to sample

• What you need: An Andersen sampling unit and Malt Extract Agar or other media plates (provided by the lab)

Andersen Sampling Procedure: please refer to owner’s manual supplied by the manufacturer

BULK SAMPLES

Bulk samples are a little trickier to take than swabs or tape-lifts, and these are more appropriate for certain kinds of materials where the spores might be present beneath the surface (such as thermal insulation.) These are usually analyzed by culturing, though the surface can also be tape-lifted (see below) for direct exam. The cultured sample is grown in the laboratory on Malt Extract Agar or other media. Results are reported in concentrations of colony forming units per gram of sample (CFU/g). The results of a bulk sample culture can be problematic because of the inconsistency of contamination of the material sampled. Additionally, Stachybotrys does not grow well on standard culture media, and an absence of Stachybotrys on a culturable sample report should not rule out this type of mold. Normal laboratory turnaround time is 7-10 days for culture and/or several days for direct exam. Rush or same day results at additional charge are available for direct exams, but cultures require time to grow and it is impossible to provide rush service for these.

Interpretation of Results

less than 10,000 is low
10,000 to 100,000 is medium
100,000 to 1,000,000 is medium to heavy
greater than 1,000,000 is heavy

For information about types of molds found on lab report, please see glossary page.

How to Sample

• What you need: a cutting tool (scissors, knife, etc.), baggies

Bulk Sample Procedure:

1. Remove approx. 1 square inch of material (about the size of a quarter). Try not to touch the sample with bare hands (use the baggie like a glove).
2. Place sample in baggie
3. Note the location the sample was taken from. If you take more than one sample, write a unique number (01, 02, 03, etc…) and a brief description distinguishing it from the other samples (AHU supply vent, AHU return vent etc…) (Some individuals also photograph the area sampled and keep this for their records.)

SWAB SAMPLES

Swab samples are easier to take, however, you must have a sterile swab for testing (these are available from Moldlab for a nominal fee). This type of sample can be cultured and\or analyzed directly. For the cultured swab, results are reported in colony forming units per square inch of material. For direct exam swab samples, results are reported semi-quantitatively like tape-lifts (trace, minor, major, abundant). Swab samples are a good choice if the suspect area is hard to access, or if you wish to do a direct exam and a culture from the same spot. Be aware that large surfaces can have multiple mold types spanning across it, and a single one square inch swab might not be inclusive or representative of all the molds. Normal laboratory turnaround time is 7-10 days for cultures and/or several days for direct exam. Rush or same day results at additional charge are available for direct exams, but cultures require time to grow and it is impossible to provide rush service for these.

Interpretation of Results

Cultured swab samples are used if both concentration and type of mold data is needed. For information about types of molds found on lab report, please see the glossary page.

How to Sample

• What you need: sterile swabs (available from Moldlab for nominal fee)

Swab Procedure:

1. Simply swab about a square inch or so of area at the sample site. If you want quantification, measure out the area sampled and record this. Areas you might want to sample include areas of visible mold growth that are hard to access. For example, the air duct supply and return vents are good locations to sample.
2. Place each swab back into the original swab protection tube
3. Note the location the sample was taken from. If you take more than one sample, write a unique number (01, 02, 03, etc…) and a brief description distinguishing it from the other samples (AHU supply vent, AHU return vent etc…) (Some individuals also photograph the area sampled and keep this for their records.)

TAPE LIFT SAMPLES

Tape samples are the quickest and easiest method of testing. No special equipment is needed for this non-cultured sample. Results are reported semi-quantitatively as a rating (trace, minor, major, abundant) so that one can have an idea of relative amounts if more than one mold is present, though this test is primarily used qualitatively to identify visible mold or to check surfaces for trace amounts of Stachybotrys. If results are negative, a bulk or swab culture of the material might be recommended to verify results because spores can be down inside the material and can be missed by direct exam. Also, be aware that large surfaces can have multiple mold types spanning across it, and a single square half-inch tape-lift might not be inclusive or representative of all the molds. Most people use this test in combination with an quantitative analysis such as Andersen or Air-o-cell / Allergenco. Normal laboratory turnaround time is several days, though rush and same day results are available for additional cost.

Interpretation of Results

To be used to identify the type of mold to a Genus level in most cases. Not generally used for quantitative analysis, though each mold type present is rated in terms of trace, minor, major, or abundant amounts. For information about types of molds found on lab report, please see glossary page.

How to Sample

• What you need: clear tape, ziploc type baggies or slide box.

Tape Lift Procedure:

1. Simply depress a piece of clear or invisible tape to the visible mold or suspected area and lift off about a nickel size portion. Make sure there are no folds or wrinkles in the tape at the area of interest. Areas you might want to sample include spots of visible mold growth or color, damp materials like wallboard, and\or maybe places that collect dust to see what has fallen out of the air.
2. Only about a half inch square portion of the tape will be analyzed. Certain materials like wallboard might require multiples samples to be taken because multiple colonies of Stachybotrys, Aspergillus niger, Chaetomium, and others can exist side by side but be indistinguishable by the naked eye.
3. Place each sample you wish to be tested into separate Ziploc or airtight baggies and stick it against the inside of the bag. Do not stick the tape back on itself. Another option is to place the tape sample sticky side down on a glass slide, then place the slide in slide container or an airtight baggie.
4. Note the location taken. If you take more than one sample, write a unique number (01, 02, 03, etc...) and brief description distinguishing it from the other samples (Bathroom tile, Bathroom wallpaper, etc...) (Some individuals also photograph the area sampled and keep this for their records.)

EPA, OSHA, NIOSH and other occupational health related associations in the U.S. have not yet to this date established permissible exposure levels (PEL), recommended exposure limits (REL), or other limit values for aeroallergens. The general guidelines listed here represent commonly accepted interpretations and practices derived from various sources, including the American Industrial Hygiene Association and Health Canada. Please realize that the evaluation of one's specific results in terms of potential health hazards and subsequent courses of action are beyond the scope of the laboratory analysis. Links on the Consultants and Resources page provide additional guidance in this regard. Those requiring expert advisement on a particular situation should retain the services of a professional IAQ consultant.