Understanding mold- mold sampling and air quality testing


Cultured Stachybotrys (black mold) colonies obtained from drywall paper

Mold 101

Molds (or mildew) are fungi. Fungi are neither plant nor animal but, since 1969, have their own kingdom. The fungi kingdom includes such wonderful organisms as the delicious edible mushrooms, the makers of the “miracle drug” penicillin and the yeast that makes our bread rise and our fine wines ferment. Biologically, all fungi have defined cell walls, lack chlorophyll and reproduce by means of spores. Approximately 100,000 species of fungi have been described and it is estimated that there are at least that many waiting to be discovered. The vast majority of fungi feed on dead or decaying organic matter – they are one of the principle agents responsible for the natural recycling of dead plant and animal life.

Mold begins life as a spore (comparable to seeds in the plant kingdom). Spores are minuscule and are ever present in the air around us. Because of their size ranging from 3-40 microns (human hair is 100-150 microns), they are literally everywhere. In very humid air, the concentration of spores is much higher. Because of their tiny size, they are carried by air currents and only settle on surfaces in very still air. They may stay dormant for long periods of time, waiting for favorable conditions to germinate.

There are four critical requirements for mold growth – available mold spores, available mold food (organic substance), appropriate temperatures and considerable moisture.

Once germinated, the mold produces string-like filaments known as hyphae. This is the growing stage of the mold.  When many hyphae come together, the mass is known as mycelium, the visible part of the mold which can produce and release spores into the air to start new colonies. In contrast, fungi that can adopt a single celled growth habit are called yeasts. Common household molds have a characteristic “musty” or “earthy” smell, somewhat like the forest floor deep in the woods. Growing colonies of mold can also be visually observed in many cases. Most people are familiar with moldy bread or mold growth on cheese or other food products that have been kept too long, so the “green fuzzy” characteristic of most mold growth is familiar.


What does mold do?

Molds cause biodegradation of natural materials, which can be unwanted when it is your homes’ structural members or when it becomes food spoilage. They also play important roles in biotechnology and food science in the production of various foods, beverages, antibiotics, pharmaceuticals and enzymes.

Some diseases of animals and humans can be caused by molds, usually as a result of allergic sensitivity to their spores or caused by toxic compounds produced by molds. The term “toxic mold” refers to molds that produce mycotoxins, such as Stachybotrys chartarum, and not to all molds in general. Symptoms caused by mold allergy are watery, itchy eyes, a chronic cough, headaches or migraines, difficulty breathing, rashes, tiredness, sinus problems, nasal blockage and frequent sneezing.

Mold in the home can usually be found in damp, dark or steamy areas e.g. bathroom or kitchen, cluttered storage areas, recently flooded areas, basement areas, plumbing spaces, areas with poor ventilation and outdoors in humid environments. Molds are ubiquitous in nature, and mold spores are a common component of household and workplace dust.

Molds can also pose a hazard to human and animal health when they are consumed following the growth of certain mold species in stored food. Some species produce toxic secondary metabolites, collectively termed mycotoxins. These toxic properties may be used for the benefit of humans when the toxicity is directed against other organisms; for example, penicillin adversely affects the growth of Gram-positive bacteria, clostridia, certain spirochetes, and certain fungi, that cause disease.

Air quality testing

Is mold testing worth the money? This question has been asked by many home inspectors and Industrial Hygienists and there seems to be a division in the ranks. At Stonegate Home Inspections Ltd, we are of the opinion that air quality testing is not worth the investment for the average homeowner but there are certain circumstances where you may have to pay for a mold sampling. One such scenario would be to prove to an insurance adjuster that the staining on the walls/roof/floor or in the attic or crawlspace is mold, not just dust or dirt.

Note that an air quality test is different from mold sampling. An air quality test tells you how many spores or other contaminants per volume of air are present at the time of testing whereas mold sampling will tell you if what you see is mold, and even what type of mold (depending upon the lab work selected). Results from air quality testing are a hotly debated subject, for more information I recommend the following article http://forensic-applications.com/moulds/sampling.html

Stonegate Home Inspections Ltd offers Mold sampling, Air Quality testing and Inspection Services that will allow you to determine the extent of any water damages, resultant mold problem or air quality problem.



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