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The Fungus Among Us

Mold, found almost everywhere outdoors and indoors, can contribute significantly to poor indoor air quality (IAQ) and sick building syndrome (SBS). The problem is especially relevant for school buildings — nearly 55 million people, 20 percent of the U.S. population, spend their days inside elementary and secondary schools, and a 1995 federal report estimated that half of the nation's schools have (IAQ) problems.

According to the U.S. Environmental Protection Agency (EPA)'s “Tools for Schools” program, indoor levels of air pollutants often are two to five times higher, and occasionally 100 times higher, than outdoor levels. Students are at greater risk because of the number of hours they spend indoors and because children have less-developed immune systems.

To ensure they are providing a healthy environment for learning, school administrators should be familiar with mold — what causes it to grow, how to prevent that growth, and how to be alert for health problems that might be caused by exposure to mold.

Understanding mold

Molds are fungi, which break down organic matter. Without molds and other fungi, we would be soon overrun with thick layers of dead trees, leaves and other expired organic materials.

Mold spores enter buildings through doors and windows, wall penetrations, or by attaching to people, pets or objects that come into buildings. Like all buildings, schools have viable mold spores, thermal environments desirable for mold growth and abundant food sources such as wood, paper, carpet, wall board, ceiling tiles and cafeteria foods. Mold spores will remain dormant until adequate moisture becomes available.

More than 645,000 known species of fungus and more than 100,000 mold species can be found growing on soil, foods, plant matter and various other materials. At least 1,000 species of mold are common in the United States, but only a few dozen are thought to be common in buildings and worthy of note.

According to the Centers for Disease Control (CDC), the most commonly found species of mold are cladosporium, penicillium, aspergillus and alternaria. Aspergillus and penicillium are considered toxin producers and have been implicated as the cause of some health problems. Stachybotrys chartarum, less common indoors than the others mentioned, is a more notorious toxin producer and is considered by some mycologists to be one of the causes of “sick building syndrome.”

Mycologists, physicians, public- health officials and attorneys often disagree about the health effects of mold in buildings; conclusive evidence is hard to identify. In fact, the EPA has yet to establish any regulations or guidelines for evaluating the potential health risks associated with molds. However, it certainly can be said that mold growth in buildings is an unhealthy condition for people and potentially destructive to the facility's structure.

Mold has been linked to short- and long-term health problems, including asthma, respiratory-tract infection and disease, allergic reactions, headaches, nasal congestion, eye and skin irritations, coughing, sneezing, fatigue, dizziness and nausea. Furthermore, poor IAQ can contribute to closing of schools, create liability problems, and strain relationships among parents, teachers and school administrators.

Combating mold

Although there is no practical way to eliminate mold spores from a building's indoor environment, the best way to stop mold from growing and becoming a potential health problem is to take away the source of moisture. When excessive humidity, moisture or water accumulates indoors and is unnoticed or unaddressed, mold will grow. Consider following these steps to minimize water or moisture accumulation and discourage mold growth in schools:

  • Humidity control Provide proper air-conditioning or ventilation systems to maintain indoor humidity levels between 30 percent and 60 percent. Humid spaces (toilet rooms, locker rooms, kitchens, janitors' closets) and associated fixtures or equipment (showers, hoods, dishwashers, dryers) should be ventilated directly to the outside.

  • Building inspections: Look for visible signs of mold growth, or investigate areas with noticeable moldy, musty odors, discolorations, stains or fuzzy growths on the surface of building materials. Also look for visible signs of water damage (ceiling tiles, basement walls) standing water (toilet rooms, mechanical rooms) or condensation (windows, exterior walls, roofs, floors or piping). Searching behind and underneath building materials, including destructive testing, may be necessary if your staff suspects mold growth but it is not immediately visible.

  • Leaks, spills or flooding. Clean and dry surfaces damaged by water within 24 to 48 hours. Fix or repair the source of the moisture problem or leak. Clean and disinfect mold on hard surfaces with water, detergent or bleach, and replace materials heavily damaged by water and experiencing mold growth.

  • Condensation control or removal. Minimize the potential for condensation to form on windows, exterior walls, roofs, floors or air-conditioning piping by providing additional insulation or vapor barrier. For equipment drain pans and piping, ensure that proper drainage is provided and the correct type of insulation is used on cold surfaces. Closed-celled insulation is preferred over fiberglass insulation on cold pipes and equipment.

  • Floor and carpet cleaning Clean up spots and stains as soon as they occur and prevent excess moisture from accumulating during cleaning operations. Avoid using carpet where moisture problems are regularly anticipated (basement floors, drinking fountains, sinks).

Once you suspect or determine that mold is growing, take steps immediately to minimize further damage and the potential health effects. The first priority is to identify the moisture source and correct the problem. In some cases, this may require the help of a professional to investigate all the potential moisture sources. Laboratory testing, including air, wipe and bulk samples, may be necessary to help determine the types of molds present and establish the potential health risks.

When you have identified the moisture sources and have completed mold testing, develop a remediation plan and put it into action. The remediation plan may include cleaning and disinfecting the contaminated area and partial or total removal of the contaminated materials. For most large-scale mold remediation, including cleaning, disinfecting and removal, bring in professionals who are experienced in this type of work.

Weidner, PE, is an engineering manager with Brinjac Engineering, Harrisburg, Pa.


▪ 30 TO 60

Provide proper air-conditioning or ventilation systems to maintain indoor humidity levels between these percentages.

▪ 24 TO 48

Clean and dry surfaces damaged by water leaks, spills or flooding within this many hours of occurrence.

▪ 1,000

Number of species of mold that are common in the United States. Only a few dozen are thought to be common in buildings and worthy of note, though.

▪ 50

Percentage of the nation's schools with problems linked to poor indoor air quality (IAQ), according to a 1995 federal government report.

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