Breathing In

July 1, 2008
Recognizing and controlling mold are key to good indoor air quality in education institutions.

Healthful indoor air quality in education facilities can improve the learning environment for students, enhance teacher job satisfaction, and reduce staff complaints. A proactive indoor air quality program helps identify and eliminate conditions that could lead to IAQ complaints, building-related illnesses and workers' compensation claims.

Water intrusion and the mold growth that often results can present significant cleanup and remediation costs, and those may not be covered by some insurance policies.

Water and mold factors

Schools typically have large buildings and large roof areas. As a school's roof ages, the probability of leaks associated with storms increases. Also, plumbing leaks or sewer backups that allow water into a school often lead to a mold and bacteria problem. Water intrusion that occurs during school construction and renovations also is associated with uncontrolled mold growth.

The key to control is preventive maintenance of building systems, as well as regular inspections to identify leaks. Thorough planning prior to construction is critical to avoid moisture from entering the structure. Contractors should be required to protect construction materials from precipitation once they have been delivered to a site. Additionally, building openings should be protected when possible to reduce the amount of moisture that enters the interior of the structure during construction.

Weather influences the degree of mold risk. School buildings situated in areas with high precipitation or persistent high humidity must defend against the outdoor conditions. In order to control indoor mold growth, the humidity should be kept below 60 percent relative humidity. Properties situated within flood-plain areas also may need special design considerations, such as sump pumps, moisture barriers and exterior grading, to prevent rising surface and ground water from entering the structure. Basements and crawl spaces that are persistently high in humidity can be sources of mold that can damage stored contents and building structure integrity.

Interior moisture sources from school activities such as indoor pools and locker rooms also can contribute to the humidity levels within the structure. The heating, ventilation and air-conditioning (HVAC) systems in these spaces need to be designed to handle the excess moisture load.

School buildings that have a history of water leaks present a higher degree of mold risk. Persistent small leaks that are not resolved, such as small roof leaks or leaks around window frames, commonly are associated with uncontrolled mold growth. More extensive leaks that take longer than two days to clean up and to dehumidify the area also are high risk indicators. If porous or semi-porous materials such as school books, carpeting, art projects and industrial wood-shop dust have gotten wet and remain within the building, these materials are likely to harbor mold growth.

Clean it up

Preventive maintenance of HVAC, plumbing and other building systems can reduce the potential for mold growth. Buildings and maintenance staff that disregard HVAC maintenance of basic components such as filter changes and condensate drains are at increased risk. HVAC systems that cycle off during non-occupancy hours to save energy can result in fluctuations in temperature and humidity conditions, which may promote mold growth. Undersized and oversized HVAC systems also are associated with inadequate moisture control.

The EPA document “Mold Remediation in Schools and Commercial Buildings” provides guidance on cleanup methods, personal protective equipment (PPE) and type of containment suggested. Also, the New York City Department of Health has published Guidelines on Assessment and Remediation of Fungi in Indoor Environments. The guidelines help to define the potential degree of risk and provide suggested cleanup methods based on the extent of damage and the building materials involved. These guidelines outline general abatement strategies based on the square footage of moldy area. The levels are defined as follows:

  • Level I: Small Isolated Areas (10 sq. ft. or less), such as ceiling tiles and small areas on walls.

  • Level II: Mid-Sized Isolated Areas (10 to 30 sq. ft.), such as individual wallboard panels.

  • Level III: Large Isolated Areas (30 to 100 sq. ft.), such as several wallboard panels.

  • Level IV: Extensive Contamination (greater than 100 contiguous square feet in an area).

  • Level V: Remediation of HVAC Systems.

If mold growth has been a problem in the past, or if remediation has occurred, the cleanup methods used can be an indication of the probability of a reoccurrence. If cleanup was slow to occur (more than two days) after the leak, and if it was limited to air drying and vacuuming up water, that could be a sign that the cleanup was inadequate. Cleanup should include:

  • Discarding water-damaged porous and semi-porous materials.

  • HEPA vacuuming.

  • Containment of work areas.

  • Dehumidification.

  • Clearance inspections and sampling.

The New York City Department of Health Guidelines, citing ASHRAE 55-1992, suggest that:

“In all situations, the underlying cause of water accumulation must be rectified or fungal growth will recur. Any initial water infiltration should be stopped and cleaned immediately. An immediate response (within 24 to 48 hours) and thorough cleanup, drying, and/or removal of water-damaged materials will prevent or limit mold growth. If the source of water is elevated humidity, relative humidity should be maintained at levels below 60 percent to inhibit mold growth. Emphasis should be on ensuring proper repairs of the building infrastructure, so that water damage and moisture buildup do not recur.” (Section 3, Remediation, Guidelines on Assessment and Remediation of Fungi in Indoor Environments, New York City Department of Health)

Evaluating risk

If a school has indoor air quality complaints, it may be necessary to consult a certified industrial hygienist experienced with resolving indoor air quality issues in schools. An industrial hygienist can:

  • Sample for mold, bacteria, volatile organics, dust, carbon dioxide and comfort parameters.

  • Evaluate ventilation systems and compare the results with ASHRAE standards.

  • Evaluate and develop a school's IAQ program.

  • Explain air-sampling results and observations to school administrators, teachers and parents.

  • Develop, in conjunction with the buildings and grounds staff, proactive indoor-air-quality programs.

Acceptable indoor air quality requires the control of airborne contaminants, the introduction of fresh outdoor air, regulation of temperature and humidity, and proper design and maintenance of HVAC systems. Uncontrolled growth of mold and bacteria indoors can expose students and school staff to unhealthful conditions, result in property damage, and impair the use of school buildings.

Because mold and bacteria are present naturally in indoor environments, the recognition of those factors that promote their growth indoors is critical to control their amplification. The key to biological contaminant control is to prevent water from entering school buildings and to control the relative humidity inside.

Mahoney, CIH, CSP, is vice president of risk control for Professional Underwriters, Exton, Pa., which provides risk-management services and insurance products to schools, municipalities and public authorities. He can be reached at [email protected].

24 to 48
Response time (in hours) necessary to help prevent mold growth after water infiltration occurs.

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