Healthy Indoors Magazine - USA Edition

Healthy Indoors 29 building occupants may still be experiencing ex- posure to allergenic spores. The way in which testing data is presented can be confusing and even misleading. Someone with mold allergies might be relieved if the sam- pling analysis states that the mold count is high- er outdoors than indoors. But exposure to indoor mold spores tends to be constant, whereas ex- posure outdoors tends to be more seasonal and weather-dependent. And in modern life, many of us spend up to 90% of our time inside buildings, even when we exercise, so exposure to mold growth indoors is a more constant threat than ex- posure to mold growth outdoors. Most labs do not differentiate between individ- ual mold spores and chains or clusters of spores, the indoor presence of which indicates indoor growth. Chains and clusters of spores outdoors are usually broken up by wind turbulence, so a count of 12 individual spores outdoors is not the same as a count of 12 spores indoors, if those indoor spores are in a chain or cluster. Labs also don't always identify conidiophores —the spore-producing structures of molds. If an indoor sample contains conidiophores, there is ample reason for concern. For all these reasons, the results of mold air testing alone should be greeted with a healthy bit of skepticism. The visual inspection to look for po- tential locations of mold growth, as well as a build- The person doing the mold testing has to know what he or she is doing. Some testers will sample in a mold-contaminated basement first, and then go around and sample other areas of the build- ing - all the while carrying spores on his or her clothing from the basement that can be picked up in samples taken in other rooms. Then the lab re- sults could suggest that the mold problem is wide- spread, rather than in just one location. Lab results can be inaccurate. In a recent study, the authors (Robertson L. and Brandys, R.) sent identical spore-trap samples to seven different labs. At each lab, the most experienced microscopist examined 100% of the samples (most analysts routinely look at only 25% to 50% of a sample). Spore counts for identical types of mold differed in some case by as much as a fac- tor of 10, and only 50% of the labs successfully identified Pen/Asp (Penicillium or Aspergillus) spores—the most common mold growth associ- ated with damp buildings. I have seen many serious identification errors from even some of the bigger labs, where inexpe- rienced microscopists may have rushed through samples. One lab identified spray-paint spheres as Aspergillus mold spores, and another lab iden- tified candle soot as "toxic black mold." Many samples are culturable, meaning that they gather living spores, which labs then count. Dead spores are still allergenic, though, so even if the mold counts in a culturable sample are low, Bottom of baseboard heating convector with allergenic dust May Indoor Air Investigations LLC Photomicrograph of Aspergillus mold spores May Indoor Air Investigations LLC

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