By Dorothy Wigmore

Dorothy Wigmore is a long-time health and safety specialist, trained in occupational hygiene, ergonomics, work organization/stress and education. A former journalist, the Canadian has worked in the U.S. and Mozambique and been involved in efforts to prevent violence on the job since 1989.

A defunct greenhouse—still connected to classrooms—spreads mold spores. An indoor pool without proper ventilation sends wet air into nearby rooms. District officials react slowly to high humidity, mold or dampness complaints, claiming, for example, “We only left the AC off for a few days,” but not recognizing that this August was New Jersey’s second-hottest August since 1895 and its wettest since 2011. Work Environment Council of New Jersey (WEC) investigations find air conditioning issues are the main reasons for mold growth in New Jersey schools.

The results—sick people and sick buildings—are a widespread issue in the state. Dozens of schools were closed, or opened late, in September. Teachers found musical instruments and cameras covered with mold and classroom walls and ceilings damp with black spots. Staff and students got sick. It’s still going on, although colder weather has improved some situations.

What’s the problem with mold?

Mold is a well-known health hazard. To grow, the fungi need moisture, oxygen, the right temperature and something organic. Indoors, mold spores float through the air to grow on—and sometimes destroy—building materials and surfaces.

The spores can cause health problems, affecting teachers, other staff and students, especially those with asthma or compromised immune systems. Many studies make these connections. In 2012, the National Institute for Occupational Safety and Health (NIOSH) issued an alert about preventing respiratory disease from dampness in schools and other locations. It reported that dampness and mold are linked to a wide range of allergy, respiratory and skin symptoms, infections and illnesses, and can cause asthma or make it worse. Six years earlier, an information bulletin from the New Jersey Public Employees Occupational Safety and Health (PEOSH) program provided details about the effects of mold spores and how to prevent and fix the hazard.

Effective ventilation with air conditioning does more than prevent mold growth. It also provides thermal comfort.

How should mold problems be prevented or fixed?

Dampness, mold and indoor air quality go together. The key to preventing mold is controlling and avoiding moisture. It involves building design and maintenance, and quick responses when dampness, water or mold are found.

Effective, functioning ventilation is an essential building feature for mold prevention. NIOSH and the American Society of Refrigerating Engineers (ASHRAE), an authority on building ventilation, say these mechanical systems are needed to limit moisture inside buildings.

What kind of ventilation is needed?

Ventilation systems should distribute adequate, clean outdoor air, control temperature and relative humidity, and remove odors and contaminants by filtration and dilution. To avoid mold and dampness, the system has to move air enough to prevent high humidity indoors; in summer, it must cool the air to remove moisture.

The EPA recommends keeping indoor humidity levels between 30 and 50 percent. But outdoor air can be much higher, as it was last summer. Without a cooling system, or one that works properly, there is no mechanism to reduce high humidity once outside air is in the building. Dehumidifiers help in small areas, but they are not effective when humidity levels exceed 60 percent.

Taking another tack, ASHRAE and NIOSH recommend keeping the dew point, the temperature at which water vapor condenses, below 55 F and making sure ventilation ducts are tightly sealed so negative air pressure doesn’t draw humid air into building cavities, inside walls and above ceilings.

What ventilation does your school have?

Schools may have a centralized system, HVAC, unit ventilators or a combination of these two systems; not all have air conditioning (i.e., cooling) throughout the building. Some have neither and rely on “natural ventilation” using windows and doors to move air around.

The main elements of an HVAC system are:

• Positive pressure: the pressure in an area is higher than neighboring ones, so outside air doesn’t get in.

• Outside air intakes are set away from contaminant sources.

• Filters, including high-efficiency ones, to capture mold spores.

• Heating, cooling and humidification elements for appropriate thermal comfort that vary by season and humidity levels.

• A supply fan and ducts to distribute air.

• An exhaust/return fan to send room air to a mixing chamber.

• A mixing chamber to combine outside and returned air.

A unit ventilator is a baseboard, ceiling, or above-ceiling box running along an outside wall. It takes in outside air and room air and mixes it. In the winter, the unit ventilator heats the mixed air and blows it into the room. Some provide air conditioning in the summer.

Whatever the system, the air intake should not be blocked and its parts need to be inspected and maintained regularly. Dirt and both standing water and moisture are unacceptable. Problems need to be fixed as soon as possible as required by New Jersey law.

Indoor air quality

Effective ventilation with air conditioning does more than prevent mold growth. It also provides thermal comfort. The New Jersey Assembly recently passed A-665, “An Act Concerning Temperature Control of Public School Buildings.” Districts investing in air conditioning to prevent mold will also address temperature and be in good stead if the bill becomes law.

What should local associations do?

If you had mold issues earlier this year, now is the time to demand the district deal with the source. You want mold prevented if there are high humidity levels next summer.

Use the process in the NJEA booklet, Organizing for Better Indoor Air Quality and form a Health and Safety Committee. Research and document problems (e.g., using workplace maps, photos, inspections— measurements usually waste time and money as there are no agreed-upon standards regarding “safe” levels and mold is often visible). Educate members. Use the problem-solving steps listed.  Ensure those cleaning up mold are properly trained and protected.

Report moisture/water/mold. Demand immediate clean-up and effective ventilation operation and maintenance: New Jersey’s 2007 Indoor Air Quality Standard requires districts to replace or repair damaged or inoperable components and establish and follow a preventive maintenance schedule to ensure that all HVAC parts are working properly. Maintenance staff should be trained in system operation and maintenance. Mold and moisture are covered under section 13.4(c).

File PEOSH complaints on violations of the IAQ Standard when necessary. Do it using a planned approach that involves the health and safety committee and others. Click here or call 609-984-1863 for more information.


National Institute for Occupational Safety and Health (NIOSH) Preventing occupational respiratory disease from exposures caused by dampness in office buildings, schools, and other nonindustrial buildings, 2012.

NJEA, Organizing for Better Indoor Air Quality.

PEOSH: New Jersey Indoor Air Quality Standard (N.J.A.C. 12:100-13).

PEOSH: Mold in the workplace prevention and control, 2006.

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