TESTING FOR MOLD

Addressing mold requires just a little thought in order to conserve resources and not move existing mold to new locations. The following are examples of how the home/office owner can be more confident of success:

Careful Visual Inspection – Include Smell

Visual inspection is the initial step in identifying possible issues. The extent of any water damage and mold growth should be visually assessed. This assessment determines remedial strategies. Ventilation systems should also be visually checked, particularly for damp filters but also for damp conditions elsewhere in the system and overall cleanliness. Ceiling tiles, gypsum wallboard (sheetrock), cardboard, paper, and other cellulosic surfaces should be inspected also.

The use of equipment such as moisture meters to detect moisture in building materials is helpful to identify hidden sources of moisture which may lead to fungal growth. Boroscopes can be used to view spaces in ductwork or behind walls.

Sample Use and Analysis

Air Samples: The investigator collects samples of the air to determine if hidden sources of mold are present in a building. The simplest type is called the “spore trap technique” or “Air-O-Cel” in which a specific quantity of air is drawn across a surface medium. Spores stick to the growth medium and are sealed for transport to the lab. This test determines the types of common fungi that may be around, but subject to a few more variables. Air sampling is used frequently because it is relatively inexpensive. (From $45-65)

Bulk/Surface Sampling: A piece of building material or furnishing suspected of housing mold growth is cut out and sent to a laboratory. The sample can then be inspected under a microscope or even cultured in a growth medium to differentiate mold species. Bulk or surface sampling is not required to undertake a remediation. Bulk or surface samples help identify specific fungal contaminants as part of a medical evaluation if occupants are experiencing symptoms related to fungal exposure. They confirm results of air sampling if a visual inspection is equivocal (e.g., discoloration and staining). ($50-125)

Bulk samples are usually collected from visibly moldy surfaces by scraping or cutting materials with a clean tool into a clean plastic bag.

Dust Collection Samples ERMI: Samples of settled dust are sometimes collected to see how much and what types of fungi are in the dust. This type of sample is very seldom utilized in mold investigations, but may be used to evaluate the spread of insidious fungi to other areas of the dwelling. This test is more expensive and lab fees fluctuate according to size of sample runs.

Tape Lift Sample: A piece of cellophane tape placed on a surface containing discoloration that is suspected to be mold. The tape is then lifted and affixed to a glass slide. A trained mycologist using a microscope in a laboratory will view the slide and can confirm the mold present in the sample. ($50-90)

Wipe or “Swab” Samples: These are a common form of surface sampling. The investigator wipes a smooth surface with a cotton swab which is then placed in a tube and set to the lab for analysis. The swab can be “picked” apart to view the collected contamination or placed on growth media. After time for growth and development, determination of species becomes more valid. ($50-75)

Many additional sampling methods are available.

When Air Monitoring is Useful

Air sampling for fungi should not be part of a routine assessment. Since decisions about appropriate remediation strategies can usually be made on the basis of a visual inspection. In addition, air-sampling methods for some fungi are prone to false negative results and therefore cannot be used to definitively to rule out contamination. Use money wisely and not on unnecessary testing. If visual mold is present, then proceed to direct or bulk sampling.

Air monitoring may be necessary if an individual(s) are diagnosed with a disease associated with a fungal sensitivities (e.g., worsening asthma/copd, cystic fibrosis, emphysema, pulmonary hemorrhage/hemosiderosis and aspergillosis).

Air monitoring is performed when ventilation (HVAC) systems are suspected of contamination. Monitoring is used to assess the extent of contamination throughout a building, and is performed with system off and again when on.
Air monitoring is used if the presence of mold is suspected (e.g., musty odors) but cannot be identified by a visual inspection or bulk sampling (e.g., mold growth behind walls). This helps identify the closest location. In all cases air monitoring is comparative and outdoor air samples must collected concurrently.

Sample Analysis

Presence of few or trace amounts of fungal spores in bulk/surface sampling is considered background. Amounts greater than this or the presence of fungal fragments like hyphae suggests fungal colonization, growth.

Air samples should be evaluated by means of comparison (i.e., indoors to outdoors) and by fungal type (e.g., genera and species). In general, the levels and types of fungi found should be similar indoors and out, with lower counts being indoors. Many of today’s modern building techniques such as duo paned windows and weatherization do not allow for adequate ventilation. It is not unusual to find contaminants 5X or more elevated inside than out and have the source be the outdoors rather than indoors.


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