Aspergillus

The “Invisible” Mold

Aspergillus is the mold most commonly associated with health-related reactions and is also the most problematic mold in the Southeast. More alarming is that Aspergillus is rarely visible. Undetected, it can saturate the air in your home or office with spores that continuously wear on your immune system and result in a host of heath reactions.

Aspergillus is rarely visible?? Under normal conditions, Aspergillus tends to grow uncolonized, meaning that active growth is not in one large, expanding mass. It is also light in color and translucent, so individual spores are difficult to detect (they are about 3 microns in diameter). In fact, visible mold in your home or office is usually not Aspergillus, but is a conspicuous red flag that conditions are suitable for Aspergillus to thrive. Cleaning visible mold alone does little to address underlying Aspergillus and its airborne spores.

So how prevalent is Aspergillus? Most people only think about mold when they have a water leak/flood or they see visible mold. Aspergillus, however, is present in concerning concentrations in a large percentage of Lowcountry homes and offices. Of the last 40 homes we tested in the Charleston area, 26 had Aspergillus counts greater than 700 spores per cubic meter (an accepted industry guideline for what would be considered clean) and 37 had Aspergillus counts greater than 230 spores per cubic meter (a more stringent guideline). Only 3 out of the 40 met the criteria for both Aspergillus and total spore counts (700 Asp/1000 Total) to be considered clean.

Aspergillus can become active at fairly low relative humidity, meaning that properly air conditioned homes are not immune. Our research has shown that in almost all cases, Aspergillus makes up a significantly larger percentage of the total indoor spores as opposed to its percentage of total outdoor spores (i.e. it is not uncommon to find Aspergillus account for 85-100% of the total indoor spore count as opposed to Aspergillus accounting for only 3-15% of the total outdoor spore count. This is evidence that the spores originate from within, even thought there is no visible mold.

Additionally, Aspergillus spore are very small, allowing significant quantities to bypass even high efficiency pleated filters.

GLS Engineering & Testing is dedicated to making the public aware of this pervasive mold and its potential dangers. We encourage you to have your home or office tested to determine if, and to what degree, Aspergillus may be affecting your indoor air.