By: Expert No. 8901, PE, CIH, CSP, REA
We have all seen molds on food or paper products (books, bathroom walls, etc.). These visible manifestations are only indicators of potential problem. The problem is actually not seen by the naked eye. It is the reproductive result of these indicators that is of concern.

Molds and yeasts are grouped under a heading of fungus (plural, fungi). Fungus is a primitive plant form that does not contain chlorophyll. Fungi must have a source of food and water to grow. Where there is sufficient food and water, fungi grow and multiply at an astounding rate. It is this growth rate that is one of two conditions for concern. Many fungi grow by expelling (1) spores or (2) small bits of growth material, into the air for creation of colonies in other areas. If these spores or growth material are created in air handling systems for instance, they can be part of the air we breath and can find their way into our bodies, impacting our immune system. The second condition is the dormant stage of fungi. Long after the water has been removed (remember food and moisture are required for growth), colonies can remain quasi-dormant: that is, spores can become air borne by disturbance such as pulling affected books off a shelf, cleaning carpets with a vacuum, removing wall board from affected areas, etc. When this happens, spores can be released and inhaled into the respiratory system where it is moist and may have food sources.

Is Mold Causing Your Indoor Air Quality Problem? Photomicrograph of Stachybotrys and Stachybotrys growing on a wall

But how does this process occur in the first place? When carpets, dust, wall board, wallpaper, insulation, or other organic products become wet or saturated with water, they become breeding grounds for spores or growth parts (hyphae). The original materials for colony formation are in the air we breath, just in smaller concentrations (we call these Colony Forming Units or CFUs). Because fungi reproduce so rapidly (even after a period of dormancy), the concentrations of spores in ducts or walls or carpets escalate accordingly, thereby increasing the concentrations of fungal reproductive materials in the air we breath.

As microorganisms compete for food and space, they have developed several forms of defense that prevent or retard other microorganisms from growing on the same food source. Human engineering has taken advantage of this condition.

Many different fungi have been cultivated for food and for food additives to make useful products such as bread, cheese, beer, wine, sausage, silage, and medicines. Alcohol (drinking) is one of the toxic products of fungi. Penicillin, a toxin produced by Penicillium mold is used to compete against bacteria. Toxins produced by some molds spoil food, others can make us sick as in poisonous mushrooms; or a great Portobello sandwich!

Fungi cause great economic damage when they attack our food, wood, paper, and fiber. Some fungi are downright pathogenic, such as Coccidioides immitis, the agent of Valley Fever. There is much concern today about the saprophytic fungi that digest dead or decaying organic matter when colonies grow in porous building materials, such as drywall, wallboard, wallpaper, insulation and ceiling tile. When these materials become wet and retain the moisture for more than a couple of days, colonies of fungi are seeded from the many fungal spores that occur naturally in the air. Flooding usually brings about mold problems as it wets many building materials and keeps humidity high. Dust in duct work is an excellent example of sporophore breeding grounds, just add humidity. Plumbing leaks and roof leaks may lead to fungus problems if not corrected immediately. Any object containing organic material may sustain fungal growth if the moisture level is high enough. High humidity and condensation are just a few sources of water that can promote fungal growth. Moisture in soil will wick through concrete and masonry unless a moisture barrier has been applied, promoting growth inside structures. Drains are required for air conditioning chiller coils to conduct the condensation safely away and prevent a place for fungus to grow.

Landscape irrigation can cause moisture in inappropriate areas. Water sprayed against buildings may promote growth on surfaces and may penetrate cracks to keep moisture levels high inside cavities. Run off from storm water and landscape irrigation may enter structures. Particularly vulnerable are crawl spaces and basements where there may be unsealed concrete and masonry for the water to wick through. And remember, stucco is designed to “breath”… it is a porous material.

ForensisGroup, Inc. experts can help you find and correct fungi problems. Airborne concentrations, surface colonies, and bulk materials are evaluated by a variety of means; each suited to a particular application. Non-viable samples are examined by microscope to yield quick analysis of spores, pollens, and insects, but are not well suited for identification of mold types. Viable samples require at least three weeks to identify mold types. This alone necessitates early action to this potential problem.

One early action for solving an indoor air quality mold problem is finding and eliminating the source of moisture. ForensisGroup, Inc. experts in architecture and construction team with certified industrial hygienists and mold experts to (1) identify and correct water intrusion and (2) assess and evaluate fungal growth. Once the fungi problem is identified (genus and/or specie), a mitigation plan and remediation of fungal growth for the area of concern can provide a complete solution.

Expert No. 8901, PE, CIH, CSP is a Licensed Safety Engineer, Certified Industrial Hygienist and Certified Safety Professional with more than 30 years experience in accident investigation systems in industrial facilities, exposure assessment strategies, reconstructing exposures, Cal/OSHA, industrial and environmental hygiene. He has thorough knowledge of federal and state environmental and worker health and safety regulations and has managed numerous programs to evaluate and ensure compliance with these regulations. He has taught at UCLA and at Cal State – Dominguez Hills.

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Electrical Engineer, Environmental Health And Safety, Indoor Air Quality, Industrial Hygiene, Molds And Fungus, Occupational Safety And Health, Safety Audits, Safety Engineer