Healthy Indoors Magazine - USA Edition

HI April 2023 - USA Edition

Healthy Indoors Magazine

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4 | April 2023 Bob Krell Founder & Publisher Publisher's Rant I 've said it hundreds of times before, but it bears repeating: Mold sampling (as we mostly do it) is a subjective science. Having just come off the road from a few of this year's national industry events, the topic of mold testing came up multiple times—as usual. Many people vocalized their opinions on the pros and cons of the various sampling and analysis methodolo- gies currently being used. Spore traps and mycotoxins got their usual panning from some well-known faces, but what was mostly missing was what I believe to be a glaring question: Are we looking at the right parameters regarding indoor mold and occupant exposures? Now, I need to preface all this by not- ing I have been around for some time, in fact, before the now commonly used spore trap cassettes even existed. Back in my day, besides having to walk miles to school, up- hill, both ways, we had to apply a coating of lithium grease to glass slides to collect spore trap samples. It was messy and easy to mess up your collected air samples. The common air sample methodology in the early 1990s when I began actively involved with consult- ing for mold-related indoor environmental projects was using a single-stage Anderson N-6 impactor and Petri dishes with various agar mediums. Spore traps were less com- monly used back then. The advent of the spore trap cassette changed things dramatically by making the field collection of these types of samples significantly easier to do. Of course, mold spore traps and culture air samples have limitations and blind spots. Since spore traps are analyzed via direct microscopy, the delay of growing out the culture plate samples is removed—a spore trap can be analyzed immediately rather than taking a week or longer culture. However, that plus is often overshadowed by the fact that many spores look the same under a micro- scope in a spore trap trace. Small, round, spherical spores get lumped together in catch-all classifications of en-Asp-like, Am- erospores, etc., making genus-level identifi- cation difficult, and species-level identifica- tions almost impossible. Of course, culture samples don't pick up any non-viable spores or fragments, and the agar growth mediums used for them are somewhat target specific for mold types. And both have questionable collection efficiencies when you collect field samples. There are numerous other parameters to utilize for testing air and surfaces, but most appear to have gaps. But the real question is do any of the widely used environmental mold sampling methodologies have a real correlation to the physiological effects on a building's oc- cupants? Are spores per cubic meter or CFUs per cubic meter a measure of the healthiness of a particular space for its occupants? Perhaps not. And that is a big problem for the industry. My editorial space is limited, so I will pause here after figuratively throwing a hand grenade into the discussion. Email me with your comments. This topic has been burning in my brain for some time now, and I believe it warrants a full article (which I will pen for Healthy Indoors in the near future)… stay tuned! The Subjective Science of Mold Testing Bob Krell Bob Krell is president of IAQ Technologies, Inc., a Syracuse, NY-based indoor environmental firm he founded in 1990, offering consulting, mitigation and training services to a variety of clients throughout the country and abroad. He co-founded IAQNET, LLC in 2013, and serves as publisher of its Healthy Indoors Magazine. Bob is the Producer/Director for the online video series, The Healthy Indoors Show, along with numerous other industry video projects and online events, and is Training Director for live distance learning offerings through Contact him at:

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