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Moisture Control And Remediation: Keys To Mold Control In Buildings

August 7, 2003
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Concern is growing about potential health risks due to the presence of fungi in the buildings in which we live, work, learn, recuperate, and play.

Mold control is one of the major challenges being faced today by owners and managers of buildings, with good reason: Issues related to mold include legal liability and the specter of litigation, difficulties obtaining insurance, as well as the costs associated with mold abatement.

Mold and fungus are present in almost all materials in residential, commercial, industrial, and municipal structures. For example, just one square-inch of surface on drywall may contain from one to 10 million spores.

Spores can survive without moisture, remaining dormant for decades, even centuries. In order to grow, mold requires air, suitable temperatures, and a moist nutrient. Of those, moisture is the major contributor as a “food medium” that sustains mold. The moisture does not need to be in liquid form. Because microscopic organisms need so little moisture, they can use what is present in solid materials, on the surfaces, or in the air as condensation or humidity.

A classic example of this phenomenon is the prehistoric cave paintings in Lascaux, France. The cave paintings survived virtually intact for 16,000 years. Then tourists began bringing moisture into the caves in their clothing and through their respiration. As a result, the paintings have deteriorated from microbial attack in less than 40 years.

This article addresses the two major abatement procedures for mold control: Moisture removal and microbial remediation. The first deals with denying fungi the moisture needed for growth; the second is the response to cleaning and removing mold from affected buildings.

A desiccant dehumidifier is shown being hooked up for a remediation project. Aggressive drying by desiccant dehumidifiers is the response when there has been water intrusion. (Photo courtesy of Munters.)

Moisture Control

The U.S. Environmental Protection Agency (EPA) document titled “Mold Remediation in Schools and Commercial Buildings” states that “The key to mold control is moisture control. Solve moisture problems before they become mold problems.”

A number of state guidelines also follow that logic. One lengthy-titled document is “New York City Department of Health and Mental Hygiene Bureau of Environmental and Occupational Disease — Epidemiology Guidelines on Assessment and Remediation of Fungi in Indoor Environments.” In it is the statement, “In all situations, the underlying cause of water accumulation must be rectified for fungi or fungal growth will recur. Any initial water infiltration should be stopped and cleaned immediately.”

The most efficient, productive, and reliable method of controlling indoor ambient conditions is to dry the air using dehumidification systems. On one end of the spectrum that means controlling humidity levels on an ongoing basis. At the other extreme, aggressive drying by desiccant dehumidifiers is the proven response when there has been water intrusion.

Elevated relative humidity levels pose a threat to any structure because moisture conditions will sustain mold formation. Such high levels of humidity cannot effectively be controlled by an air conditioning system. Dispelling humidity requires commercial-grade dehumidification. The most effective way to control a high-humidity environment is to employ a combination of air movers and desiccant dehumidifiers. When a room is filled with dry air, which has low vapor pressure, trapped water migrates outward and is evaporated from the surface by the dry air. This technique establishes and maintains proper humidity levels that stabilize the interior environment.

The second major threat to a structure is excess moisture that results from any source ranging from pipe or equipment leaks to flooding.

In such cases, quick action is required to dry affected materials and areas of the building to preserve good indoor air quality. The longer the water flows or wet conditions are allowed to exist, the greater the recovery problem becomes.

Microbial Remediation

In cases where mold has grown, containing and removing it is necessary to prevent further spread and to eliminate infiltration of spores into the atmosphere. Otherwise, there is the potential for health risks.

A sequence of events is implemented during the removal — or remediation — process:

  • Evaluation: For all projects, regardless of the amount or level of microbial growth, an industrial hygienist, indoor air quality specialist, microbiologist, professional engineer, or licensed health professional should be used as an independent consultant to determine and direct the microbial abatement. Utilizing an independent consultant ensures that the company conducting remediation is unbiased and has no conflict of interest.

  • Containment: To minimize exposure to mold by the remediators and building occupants, constructing barriers and utilizing negative air pressure to contain spores isolates the infected area. Only authorized personnel are allowed into the containment area.

  • Isolation of HVAC system: The heating and air conditioning system in the affected area is deactivated and ambient conditions are controlled locally, for example, by using a combination of desiccant dehumidification and heating or cooling as necessary.

  • Demolition: Removal of infected materials, cleaning, and application of fungicidal coatings to deter future mold growth are accomplished. Cleaning includes several options: wet washing, wire brushing, or sanding, to name a few. HEPA vacuum systems are used on the surfaces. The cleaning, vacuuming, and fungicidal process is repeated several times.

  • Analysis: A third-party environmental consultant completes inspection and samples are taken for laboratory analysis.

  • Conclusion: Upon receipt of successful test results, barriers are removed and the area is ready for remodeling.

    Unlike asbestos, for which there now are regulations, there are no government standards, threshold limit values, or EPA regulations for airborne mold contaminants. For that reason, it is important that building owners and managers work only with reputable remediators and plan ahead. One way is to create a disaster recovery plan, which can limit the extent of water damage occurrences by defining and prioritizing the recovery of areas within a facility and stating immediate next steps. Proper planning and fast action are most certainly the best defense to preventing a water damage event that encourages mold growth.

    Paul Harkins is business development manager for remediation with Munters Moisture Control Services (MCS). He is a Board Certified Microbial Remediation Supervisor by the American Indoor Air Quality Council. He also is an approved instructor in Ohio and Kentucky for insurance and real estate professionals for continuing education accredited courses in mold remediation. He has 28 years experience in disaster restoration, the past 3 years of which have been focused on microbial remedial abatement. Harkins can be reached at 800-686-8377 or by e-mail at pharkins@munters.com.

    Publication date: 08/11/2003

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