Age of mold contamination in buildings:
This article discusses how we assess the activity or inactivity of mold contamination in a building, what difference that means (or does not) in risk to building occupants, and how we can find evidence suggesting that a given mold contamination case is new, old, or includes both old and new fungal growth.
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Would you please let me know how an individual (or lab) would test for whether a mold found on attic sheathing is active vs. inactive?
Research on-line has told me the test for active vs inactive is whether it smears when you rub it. Is there a more technical test that can be done? Should a lab be able to tell me this when I supply a sample? - M.O.
The question of how we determine whether or not mold in a test sample is "active" is a bit misleading, although some surface test samples of mold do indeed give compelling evidence of recent active fungal growth. Our site photograph of moldy roof sheathing (above left) is an example. Is this mold growth "active" or "inactive", and does activity make much difference in risk to building occupants?
At MOLD AGE, HOW OLD is the MOLD? we discuss visual clues that help determine the age of mold contamination in buildings or on building surfaces. There we explain what dried, desiccated, "old" mold growth may look like on a surface, in a test sample, and under the microscope. Among other factors, we distinguish between
Often we can confirm recent fungal growth in a tape sample by the presence of certain growth structures, hyphal buds, or even the state of a conidiophore.
Our photo of Epicoccum sp. fungal spores and hyphae (above left) collected from a building surface shows intact, fragile hydrated complete spores still connected to hyphae - this mold growth is recent and might indeed be considered "active mold growth" as would the intact, hydrated, and budding Aureobasidium pullulans spores shown in our second lab photo (above right).
This burst of Pleospora spores is clearly active. Similarly, for certain species that produce long fragile spore chains, the presence of long mold spore chains is certainly indicative of nearby active fungal growth, as these chains break up rapidly into individual spores when airborne.
Conversely, highly-dessicated, fractured, or damaged fungal material that lacks budding hyphae or sporulating intact conidiophores are almost certainly "inactive" mold growth in the spot where sampled.
Watch out: "mold activity" or "mold inactivity" can be misleading conclusions about the risks associated with mold growth in buildings.
The moldy books in a college library (photo at left) were in the opinion of some people "an old inactive mold problem" but when workers began dehumidifying the area in preparation for a mold cleanup, visible clouds of Aspergillus sp. spores were released into the air by small air currents caused by simply walking down the aisle between stacks of books.
Watch out: however: using a swab or culture test for "viable mold" in buildings can give very misleading results since what grows in the culture is what likes the culture, not necessarily what is present or dominant in the building.
See MOLD TESTING METHOD VALIDITY and in
particular Mold Culture Plate Test Errors.
These reasons explain why in addition to testing to confirm the presence of mold growth, and to confirm that it is not simply cosmetic, in cases of possibly costly mold cleanup or diagnosing a possible building contribution to indoor air quality complaints, is important to have an expert perform a competent inspection of the building.
As we explain at MOLD AGE, HOW OLD is the MOLD?, especially in older buildings where there has been a recent sudden leak event associated with mold growth, it is often possible to identify pre-existing mold as well as mold-producing conditions.
In unambiguous cases, the "new" mold associated with the building leak event may, by luck, appear in a limited area of the building which maps the area wet by the recent leak, and separated by distance or building area from other moldy areas which in turn are associated with other building leaks or conditions.
The physical separation of wet areas and wet conditions may be sufficient to make a clear assignment of mold causation in such cases.
In ambiguous cases, there is fresh, active fungal growth, probably associated with a recent leak or flooding event in the building, which has grown entirely or partly overlapping pre-existing mold growth. In this case the assignment of cause and age of mold in the building can be ambiguous. If an insurance claim is involved, insurance company policy details and internal claims adjustment guidelines will determine the extent to which insurance coverage will address building remediation and repair for these overlapped-occurrence mold conditions.
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Below you will find questions and answers previously posted on this page at its page bottom reader comment box.
(July 12, 2015) Jill White said:
I have been mislead by slumlord who kept promising me she would fix the leaking roof and floor plumbing, but now the damage is total
The new management came to say that instead of repairing the home it would be demolished. Are you belongings all tainted with mold/fungi?
Where can I go to get the blood/urine/lab work to find out if my headaches, dizziness, nasal problems, worsening allergies, increased inhaler usage, lack of energy, depression, ect- .is from toxic molds inside and outside my home. Help asap-court with new landlord soon
Jill
Outdoor mold is not likely to be a source of medical illness unless someone rubs mold growth in an eye or into an open cut. But high levels of a number of indoor mold contaminants can be a cause of a wide range of health complaints.
Start by checking with your doctor.
Also see MOLD RELATED ILLNESS GUIDE
You'll find an extensive mold-guide-for-renters beginning at RENTERS & TENANTS: MOLD ADVICE & IAQ
You can find a mold doctor at MOLD DOCTORS - ENVIRONMENTAL MEDICINE
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