Going Straight to the Source

Feb. 1, 1998
School administrators frequently hear complaints from staff and community about health problems that are alleged to be caused by school buildings. Complaints

School administrators frequently hear complaints from staff and community about health problems that are alleged to be caused by school buildings. Complaints commonly include headaches, fatigue, eye and respiratory irritation, asthma attacks, skin rashes and gastrointestinal distress. In many cases, these symptoms are caused by viruses or bacteria commonly passed from person to person in close quarters such as classrooms and are not facility related.

However, these same symptoms also can be caused by poor indoor air/environmental quality (IAQ), and it can be difficult to differentiate between the two. Simply dismissing the complaints as "a bug going around" can be a serious mistake if there really are facility problems.

Improving ventilation More than 50 percent of IAQ complaints in buildings are associated with the ventilation system. This may be higher in schools due to higher population densities. Consider, for instance, that a typical office will have about 150 to 200 square feet of floor space per occupant, whereas a classroom may have only 20 to 30. If the ventilation system has operational or maintenance problems, it is felt more dramatically in a densely populated classroom. While ASHRAE Standard 62-1989 calls for a minimum supply of 15 cubic feet per minute of outside air per person in classrooms, little or no outside air is often found to be the prevailing condition where there are IAQ complaints. Too little outside air and other ventilation problems deserve the attention of facility management.

Outside air supply is controlled by damper settings and mechanical linkages. Sometimes these dampers are found closed or nearly closed, with the linkages jammed or disconnected. This can be the result of normal wear and tear or a service person's frustration with trying to deal with temperature-control complaints or high utility costs. It is usually easier and less expensive to heat or cool recirculated air than outside air.

Unit ventilators commonly are used for classroom heating, ventilation and air conditioning. Unfortunately, they often are used as storage shelves for books or other materials, which obstruct the supply vents and prevent the room from receiving the required air supply. In addition, these vents become traps for an array of trash that drops into them and restricts airflow. More frequent cleaning helps keep the air flowing.

Another common problem is dirty coils, which results in inefficient heating and cooling, as well as reduced airflow. Thoroughly clean coils at least once a year. Unit ventilators typically bring in air directly through an outside wall. Debris-waste paper, grass clippings and leaves, and bird and rodent nests-often is found in the louvers and screens that cover these intakes. Such materials block airflow and are a source of potentially harmful molds, bacteria and pollen. Clean intake screens annually or more frequently in areas where debris accumulates more quickly.

Drain pans under cooling coils frequently are found to be clogged with dirt, slime and other biological growth. This causes the air supply to pass over a water surface often teeming with mold and bacteria. Drain pans need to be designed and installed to quickly carry away condensate. These pans should be disinfected and flushed with clear water periodically to maintain sanitary conditions; frequency will depend on the system and its use. Inspect coils and drain pans each time filters are changed, at least quarterly. Keeping condensate drain lines clear prevents backups that can cause wetting of carpet, drywall or insulation, which can become moldy.

The location of outdoor air intakes with respect to other construction and site features can have a major impact on IAQ. Snow blockage can occur when unit-ventilator exterior-wall openings are too close to the ground or when air handlers on the roof are positioned where snow drifts. Shoveling snow away from such intakes needs to be a part of the facility's winter maintenance program.

A more difficult problem is where intakes are positioned near driveways, loading docks or parking lots. Engine exhaust that drifts toward intakes is a notorious cause of complaints. Rerouting traffic, banning engine idling and repositioning intakes are some of the possible solutions. Another potentially serious problem is caused by placing intakes too close to cooling towers. The mist from cooling towers can carry bacteria that causes Legionnaires' disease and other lung diseases. The best preventive measure is to have a stringent disinfection program for cooling water, and locate air intakes as far from the tower as possible.

Maintenance skills The second leading cause of IAQ problems in buildings is related to maintenance. Tight budgets make it difficult for schools to fund all of the items that need attention, and building maintenance often is well down the list of priorities. A neglected building envelope can result in roof, window and exterior-wall leaks.

Water is the key ingredient for mold and bacterial contamination. Porous materials such as carpet, upholstery, ceiling tile and drywall that become wet and cannot be cleaned and completely dried within 24 to 48 hours usually become moldy and must be discarded. Failure to discard such items can result in musty odors and a variety of health complaints.

Mechanical systems also are important causes of IAQ problems when not maintained. Plumbing leaks, for example, are common causes of mold problems and odor complaints. Poorly maintained boilers, water heaters and incinerators can produce smoke and odor problems both inside and outside buildings. Potentially deadly carbon monoxide gas can infiltrate buildings when flue pipes become blocked or corroded, or when heat exchangers fail allowing combustion gases to flow into the building. A thorough inspection of all heating equipment should be performed at least annually by a qualified technician. Consider installing carbon monoxide detection equipment in areas most likely affected by defective combustion equipment.

Keeping it clean Sanitation in a school building requires careful attention. While restrooms and food preparation areas are obvious, corridor and classroom floors are as important. Many schools have carpet, which not only is more difficult than a hard surface to keep sanitary, but also can become fertile beds for the growth of mold, bacteria and associated odors.

To combat IAQ problems, use vacuums with a beater bar and a high-efficiency filter so that microscopic dusts are captured. Also, provide enough custodial help so that furniture can be moved for complete vacuuming on a frequent basis. Try to confine food and beverage consumption to rooms with a hard floor surface that can be mopped and disinfected. Finally, keep carpet dry so that micro-organisms cannot grow. This means controlling snow and rain track-in, quickly cleaning up leaks or spills, and using supplemental dehumidification and ventilation, if necessary, to completely dry carpet within 24 to 48 hours after it has been wet cleaned or flooded.

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