DETERMINE YOUR GOAL

Mold testing should not begin without first identifying the goals, or more specifically, the questions you're trying to answer.  

Examples of common questions mold testing can be used to answer:

• Has mold growth in one area led to contamination in an adjacent room?
• Was a previous mold problem cleaned up properly?
• Has the visible mold growth led to abnormal levels of airborne mold?
• Is the mold found inside the building from an outside or inside source?

PICK THE APPROPRIATE TEST

Next, a mold testing expert must determine which sampling is most appropriate.  Opinions slightly differ among mold professionals, however, the vast majority will utilize one of the following techniques.  

Examples of common mold testing techniques include:

• Non-viable air sampling (Air-O-Cell)
• Viable air sampling (cultured sample)
• Tape lift test
• Bulk sample
• Vacuum dust test
• Allergen screen

Examples of different mold tests and preferred applications:

Non-viable air sampling.  

• The most common air sampling test used, these are most appropriate for identifying general elevations of mold spores.  For example, a basement bedroom with a musty odor.  Additionally, they are often used for clearance testing after remediation projects are completed.  

Viable air sampling. 

• Far less common than non-viable sampling, it is primarily used to connect specific mold growth to a specific IAQ problem.  For example, if you need to establish a connection between visible mold growth from a broken kitchen sink line and airborne mold that may cause a negative health effect.  This can only be accomplished with viable air sampling because it can identify both the genus and the species of the mold.

Tape lift sampling.

• Useful in distinguishing between mold growth and other similar looking substances such as efflorescence.  Additionally, tape lift samples are occasionally collected as part of post remediation verification.

Bulk sampling

• Useful in analyzing samples without an on-site visit.  For example, a shipping company finds a suspicious substance on their crates or containers.  Visiting the site won't yield much additional information and a small section of material can be easily sent to a lab.

CALCULATE THE REQUIRED SAMPLES

Mold testing isn't free, therefore a good mold testing company must accurately determine the minimum number of samples required.

Mold testing companies often consider the following factors:

• Square footage of problem area.
• Number of floors or levels in the building.
• Sensitivity of the occupants.
• Source of mold growth.

COLLECT SAMPLES

Sampling for mold utilizes a wide variety of equipment and techniques.  A qualified mold testing company will come prepared to collect any samples necessary. 

Mold testing samples are often collected with the following techniques:

• Bio-Pump or similar vacuum pump style collector.  
• Anderson plate impactor
• Micro vacuum collector.
• Tape lift samples are often used for settled dust or areas with visible mold growth.
• Bulk samples.  If a mold contaminated item can be easily removed, a portion of the item (i.e. carpet) can be sent to the lab.

INTERPRET THE RESULTS

Without a doubt, interpreting the results is the most difficult step in a mold inspection.  The reason this is so difficult relates to the nature of mold itself.  Two principles are critical to remember.  

1. Mold spores are ubiquitous.
2. Mold spore concentrations vary wildly.

Because of these two factors, analyzing mold testing results is highly subject to the opinion of the inspector.  If two inspectors look at the same result, one may tell the client it clearly indicates a problem, while the other may say the levels are perfectly normal.  This doesn't indicate that mold testing is worthless, it just requires you to move cautiously when hiring a mold inspector. 

Before hiring any mold testing company, ask the following:

• What thresholds do you use to determination contamination?
• What laboratory do you work with?
• What actions will you recommend if the samples are come back high?