Meaningful Mold Investigations Involve More Than Just Sucking Air

Water Damage Investigations – More Than Sucking Air

Far too often I receive calls from homeowners requesting that I make some sense out of another mold consultant’s report.  Usually the report consists of concentration results for a few indoor spore trap air samples and one outdoor comparison sample.  The report might include some general information about the types of mold that were found and how the indoors compared to outdoors.  My gut reaction to these inconclusive reports is usually, “So what , YOU’VE GOT MOLD, now what are you supposed to do.”    Of course the bewildered homeowner is already thinking the same thing, so I try not to rub salt in the wounds.

In defense of the consultants, who are frequently home inspectors that rent air sampling pumps, they did what the homeowner requested, which was “test the air.”  However, I do object to consultants working outside of their areas of expertise.  A qualified mold investigator would have first asked why a homeowner wanted the air tested for mold.  When I ask this question, the response is usually something along the lines of “I just want to know if I have a mold problem” or “I see mold and want to know if it is the dangerous kind.”

With these responses, a qualified mold investigator would advise the homeowner that taking a few air samples in the home probably would not answer their questions and would likely be an unnecessary expense.  This is because ninety-nine percent of the time, a qualified mold investigator can determine if a mold problem exists by conducting a detailed visual evaluation that would include moisture mapping, inspection of common problematic areas, and collecting information on the history of water damage and prior repairs.    Air sampling equipment is not the most important tool for a competent mold investigator, but he or she should come equipped with a moisture meter, thermo-hygrometer (to measure termperature and relative humidity), good flashlight, camera, pry-bar, and needle-nosed pliers, along with protective clothing and a respirator.  Not only will the qualified mold investigator assess the moldiness of the home, he or she will provide a scope (i.e prescription for remediation of the mold) and correcting the underlying cause.

Although mold sampling is not necessary to assess and remediate mold, under certain circumstances, sampling is advisable.  However, sampling should only be performed to answer a specific question (scientifically, this means to test a hypothesis).  Of course, the hypothesis can only be developed after a detailed mold inspection is completed.

When testing is performed, an investigator must understand and apply the appropriate testing methods.  For example, the spore trap sample mentioned in the first paragraph cannot differentiate certain types of mold.  Case in point is the group of mold species that are in the genera Penicillium and Aspergillus; these molds show up as the same spore type in a spore trap air sample, and can only be differentiated with culturable air samples.  Both of these molds are commonly found in homes that have experienced water damage.  However, some species in this group can also be found outdoors.  Since comparison of the types and relative concentrations of mold indoors and outdoors is a primary criterion for interpretation of sample results, simply reporting that a certain number of Penicillium and/or Aspergillus indoors and outdoors could be misleading,  inconclusive, and possibly dangerous.  For example, suppose Aspergillus versicolor, a mold that can cause infections and produces carcinogenic toxins is present indoors, and Penicillium chrysogenum is found outdoors at a similar concentration.  The spore trap sample would simply report the similar concentrations of “Penicillium/Aspergillus”, which would lead to the wrong conclusion that the outdoor air was the source of indoor airborne molds.

I could provide numerous examples of how simply “sucking air” could not only be useless, but misleading.  However, understanding what to ask for when requesting a mold assessment is far more important.  Homeowners should clearly identify why they want mold information prior to calling a consultant.  Information they should be prepared to provide includes: (1) do you see or smell mold; (2) is anyone experiencing symptoms that might be related to mold exposure; (3) is your doctor requesting the information,  (4) have you had water damage in the home; (5) how old is the home, (6) how long have you lived there; and (7) do you anticipate litigation.  In some circumstances, no testing will be required.  For others, such as litigation or physician requests, a well designed sampling plan could be essential.

Once the objectives of testing are identified, understanding the qualifications of the appropriate mold consultant is paramount to avoid wasting time and money.  An investigator performing a detailed visual assessment should possess extensive knowledge of building science (how buildings are constructed), ventilation, mold remediation, the principles of mold growth, and water damage restoration.  Although certifications in mold remediation or mold investigations can demonstrate that an individual has passed the minimal qualifications, extensive experience (minimum five years) is recommended.  Passing a one-week certification course does not guarantee that an investigator is qualified.

Relative to mold testing, in addition to the requisites for a mold investigator, a consultant who develops and executes mold sampling plans should have a minumum of a bachelor’s degree in biology, chemistry, environmental health or industrial hygiene.   Extensive knowledge of exposure hazards, quality control, data interpretation, statistics, and sampling methods are also required.   If testing is conducted, a sufficient number of samples must be collected, both spore trap and culturable air samples are required; and surface samples of dust and suspect mold growth are usually necessary.  No sampling is better than inconclusive sampling.

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