types of mold testingThere are three main types of mold testing – air samples, surface samples, and carpet samples.   We feel ERMI testing, developed by the EPA, is totally meaningless, and therefore we will not mention it in this post, but we will explain in detail in an upcoming article. Incidently,  self-testing mold kits are also meaningless, see Mold Test Kits – Are They Reliable?

Sampling is the scientific approach to mold assessment.  Mold testing provides a snapshot of the environment at the time of sampling at a particular location, as conditions can change over time.

Air sampling methods include  Culturable and non-culturable samples.  The culturable method allows the microbiologist to differentiate between species whose spores are visually similar, but it takes longer to obtain the results and it is also more costly.  In addition, there are certain types of mold that do not grow well in a laboratory setting.  Mold spores collected in a residence are grown (cultured) in a laboratory and analyzed after more extensive growth has occurred. Thus, it is believed that the non-culturable method provides a more accurate “snapshot” of the air quality,  besides being cheaper and quicker.

There Are 3 Main Types Of Mold Testing

  • AIR SAMPLES are collected using spore traps to collect mold spores floating in the air.  The purpose of collecting air samples  is to qualify and quantify the environment in relation to mold.  It tells us what types of mold spores are in the air and the quantity of spores present compared to the outside control, which serves as a baseline.  Wall cavity samples are air samples but it is not necessary to compare the results to the outside control.
  • SURFACE SAMPLES, such as a tape lift or a swab, are used to test visible mold-like substance.  It tells us if it is mold, and if so, the type(s) of mold growing at a particular location.  As a rule, surface samples complement air testing.
  • CARPET SAMPLES are used to test carpets to determine if they have been contaminated by mold.

According to the American Industrial Hygiene Association (AIHA) about 50% of mold problems are not visible.  Thus, testing the air is a vital tool to help assess air quality even when mold is not visible.

Certain conditions must be met before collecting air samples.  For 48 hours prior to sampling any stand-alone air cleaning devices must be turned off and all windows and all doors to the outside must remain closed.  Normal traffic in and out of the house or building is okay.  The reason for this is to obtain a true reading on indoor air quality without any filtering devices or mixing the outdoor air with indoor air.  In addition, the inspector must wait at least two hours after the last rain has stopped to collect an outdoor control air sample.  This is because the rain clears the air.  If the above conditions are not met, the sampling results will be inaccurate.

The mold inspector should follow a rigid sampling protocol. In order to obtain accurate results.  The samples must be collected in a precise and controlled manner by a mold inspector in the field; then, they should be analyzed with a high degree of precision by a degreed microbiologist in a laboratory.

The mold inspector should keep both a written and visual record of the sampling as it is performed.  See our post: Mold Testing Accuracy And Quality Control. He should also provide his client with a copy of the sampling records at the time of sampling, and reference them again in his report.  Should any questions arise, the mold inspector ought to be able to provide evidence of his sampling methodology.

The Interpretation Of The Laboratory Results
Is The Most Critical Part.

Assuming that the protocol of mold testing as described above has been followed by the mold inspector, the most critical part of mold testing is interpreting the laboratory results.  It is extremely important to select a seasoned and reputable mold inspector.  There are mold inspectors who tell their client that they don’t have a mold problem when they do, and there are others, just to be on the safe side, who tell their client they have a mold problem when they don’t.  We are often hired by clients who seek a second opinion, so we know.

The types of mold samples collected is determined by the suspected or actual mold problem. Client should receive two reports; a laboratory report and a companion report written by the mold inspector which should explain the laboratory results in more detail and provide his client with a mold remediation protocol as needed.

For more information, feel free to contact us.  We operate a mold assessment company in Central Florida and are authors of this blog and several books on mold.

Written by Charles & Danielle Dobbs – Professional mold assessors, expert witnesses, authors of several books on mold, and mold education bloggers

Charles & Danielle Dobbs - Professional mold assessors, expert witnesses, authors of several books on mold, and mold education bloggers

Professional mold assessors, expert witnesses, and authors of MOLD MATTERS- SOLUTIONS AND PREVENTION, MOLD PREVENTION TIPS FOR THE GREEN BUILD INDUSTRY, and INSPECTION AND SAMPLING METHODOLOGIES FOR TRAINING MOLD ASSESSORS.

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