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  • Writer's pictureCorey Provencal

Interstitial sampling, aka. The wall cavity air sample.

Post on Wall Sampling from Forensic Applications, Inc. via Facebook

Nowhere except in the “toxic mould industry” have so many Industrial Hygiene tools and techniques been perverted and abused. And amongst the most abused are the “size selective samplers” which have been commandeered by “certified mould inspectors” for their nefarious activities – which usually involve bamboozling home owners into believing they have a mould problem which can only be corrected by costly “remediation.”

As legitimate Industrial Hygienists, mycologist, microbiologist, the US EPA, US Centers for Disease Control, World Health Organization, and a large number of State Health Departments have been cautioning consumers against using air sampling and other methods for moulds, the “toxic mould industry” has now settled on a new scheme – wall cavity spore sampling.

Also known as “interstitial wall sampling,” this technique is a derivation of the common Air-O-Cell spore trap. In the method, the “toxic mould inspector” inserts a small tube into a wall cavity and sucks air out of the wall cavity through a spore trap. Then, based on the (invalid and uninterpretable) sample result, the practitioner informs the homeowner they have toxic mould in their wall cavity. Not surprisingly, the certified mould inspector then announces that they, or their cousin, just so happen to also own a certified toxic mould remediation company who will take care of the problem!

In fact, the technique has no validation, and sample interpretation by these practitioners cannot withstand scientific scrutiny. The use of wall cavity sampling during a normal mould assessment in a structure would never be performed by a legitimate knowledgeable investigator such as a mycologist, microbiologist or Industrial Hygienist and currently remains primarily a gimmick in the purview of the “toxic mould” scam artist who otherwise lacks any legitimate knowledge in the assessment of indoor moulds.

Regardless of the sample result, the results cannot be translated into a meaningful human exposure statement, and neither can the result be translated into a statement that is germane to structural issues, water loss or even mould growth in the wall or the structure.

In short, the method is primarily used to impress the client, and does not produce any valid data that can be used in a legitimate mould assessment or human exposure assessment.

Furthermore, the method can be easily manipulated by the practitioner to either produce a “high value” or a “low value” depending on what the “toxic mould inspector” wants the sample to show.

ALL wall cavities contain mould. Virtually all drywall paper contains Stachybotrys atra, the boogey-man (and the golden cash-cow) of the certified mould inspector. If one bangs on the wall hard enough and long enough, one will get a desirably higher count for “black mould.”

Several scientific studies have clearly demonstrated that mould found in wall cavities does not impact human exposures, degrade indoor air quality, or otherwise pose a threat to the structure or occupants of a structure. No studies have shown that the hollow wall cavity spore trap sampling has any legitimate utility in a routine mould assessment, post remediation clearance sampling, or other “mould remediation” project.

Visibly water damaged surfaces should be properly addressed such that the visual aspects and the structural integrity of the material be returned to a satisfactory visual condition. Appropriate remediation activities may be as simple as wiping the mould from the surface of the material and, if necessary, just repainting the surface (presuming the moisture problem has been corrected).

Although willy-nilly fishing expeditions hunting down hidden mould are certainly standard industry practice of the “toxic mould” scam-artists, such assessment techniques have never been considered an acceptable practice by legitimate experts in the field of human exposure assessments.

Usually, an homeowner’s first clue that they have not selected a legitimate knowledgeable consultant in a mould related issue is when the consultant wants to collect “samples;” any kind of samples, air, tape, surface or interstitial wall cavity samples. A legitimate mould inspector virtually will never be identified as a “certified mould inspector” and will virtually never elect to collect any kind of samples.

•John P. Lapotaire, CIEC •Certified Indoor Environmental Consultant •Microshield Environmental Services, LLC

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