Indoor Air Quality - Tools for Schools Action Kit for Canadian Schools

Chapter 3: IAQ Backgrounder

Understanding IAQ Problems and Solutions

Over the past several decades, people's exposure to indoor air pollutants has increased due to a variety of factors. These include:

1. the construction of more tightly sealed buildings;
2. reduced ventilation rates to save energy;
3. the use of synthetic building materials and furnishings;
4. the use of chemically formulated personal care products;
5. the use of pesticides and housekeeping supplies;
6. the increased complexity of modern building systems;
7. building deterioration due to age, improper maintenance or design;
8. increased loading of school buildings due to larger class sizes or expanded use of facilities; and
9. a reduction in resources (money and staff) to operate and maintain school facilities.

Other factors such as lighting, noise and electromagnetic fields (EMF) may also have an impact on the indoor environment. While these factors should be recognized, they are not typically addressed as part of an IAQ assessment.

In a broad context, IAQ is the result of the complex interactions among buildings, building systems and people. Four basic factors affect IAQ:

• sources of indoor air pollutants;
• heating, ventilation and air-conditioning (HVAC) systems;
• pollutant pathways; and
• occupants.

All of these factors must be carefully considered when assessing a building. A rational, balanced approach will result in the most healthy, efficient and effective building performance.

Sources of Indoor Air Pollutants

Indoor air contaminants can originate either within the school building or be drawn in from outdoors. If pollutant sources are not controlled, IAQ problems can arise, even if the HVAC system and other building components are properly operated and maintained.

Air pollutants consist of tiny particles or particulates (such as dust, pollen, soot or fungal spores), fibres, mists, aerosols, and gases. Some typical examples are listed in the following table.

Typical Sources of Indoor Air Pollutants

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Many potential pollutants are found in the indoor environment. Contaminants may result from a single source or from a combination of sources.

In addition, indoor air pollutant levels can vary by time and location within the school building, or even within a single classroom. Pollutants may be present only once each week such as when floor stripping is done, or continuously such as when mould is growing in the air distribution system. Pollutants can be emitted from specific areas, such as laboratory storage rooms, newly installed or refinished flooring materials, or freshly painted surfaces. Each school should consider developing policies on fragrance use in consultation with provincial and territorial authorities.

HVAC System Design and Operation

The heating, ventilation, and air-conditioning (HVAC systems include all the heating, cooling, and ventilating equipment serving a school. A properly designed and functioning HVAC system:

• controls temperature and humidity to provide thermal comfort;
• distributes adequate amounts of clean outdoor air to meet the ventilation needs of school occupants;
• provides air circulation; and
• isolates areas and removes odours and pollutants through pressure control, dilution, filtration, and exhaust.

Not all HVAC systems are designed to accomplish all of these functions. Some older buildings rely only on natural ventilation. Others lack mechanical cooling equipment, and many buildings have little or no humidity control.

Here are some of the key characteristics of a properly functioning HVAC system:

• It must provide reliable, continuous operation.
• If the system is designed for variable air flows, it must provide adequate minimum amounts of clean outdoor air and total air distribution.
• The building operators must be trained in the operation and maintenance of the system.
• The system must provide adequate access for the inspection and maintenance of all components.

Many different unitary, central and hybrid ventilation systems can provide adequate performance if they are properly designed, installed, maintained and operated.

Pollutant Pathways and Driving Forces

The building envelope is designed to provide a barrier between the outdoor and indoor environments. Since these environments often vary, the building envelope will be subjected to loads from temperature, wind, humidity, mechanical forces, and other factors.

A well-functioning building envelope can resist these loads and provide durable, long-term performance. However, a building envelope that cannot resist the loads it faces - due to inadequate design or maintenance - will fail, and may cause indoor air quality problems.

Some examples of building envelope failures (and their primary causes) are:

• improper flashings that allow moisture to enter walls (design or workmanship);
• snow/ice build-up on roofs and subsequent water leakage (design: slope or insulation; maintenance: membrane repairs, snow clearing; operation: interior temperature);
• mould growth in exterior walls (design: air/vapour barrier and insulation details; maintenance: inspection, sealing, repair; operation: excessive humidity, building pressurization, furnishings placed on interior of exterior wall surface, air flow).

In many cases, an indoor air quality problem is the result of a number of inter-related building performance problems.

Airflow patterns within buildings result from the combined forces of mechanical ventilation systems, human activity, and natural effects such as wind and temperature. Air pressure differences created by these forces move airborne pollutants from areas of higher pressure to areas of lower pressure through any available openings in building walls, ceilings, floors, doors, windows, and the HVAC system.

These principles are important to consider when assessing how contaminated air from work areas, equipment, outdoors, or the soil can enter the building envelope and circulate within the building. They also identify potential control strategies such as providing adequate air sealing, reducing intentional or unintentional openings, proper balancing of air pressure, and the use of mechanical ventilation equipment.

Building Occupants

The occupants of schools include the staff, students, after-hour users and other people who spend extended periods of time in the school. The occupants can contribute to indoor air quality problems by their activities, what they bring to school, what they wear, and how they use the building. The occupants can also be affected by poor air quality. IAQ problems often cause non-specific symptoms rather than clearly defined illnesses.

Symptoms often attributed to IAQ problems include:

• headache, fatigue, and shortness of breath;
• sinus congestion, cough, and sneezing;
• eye, nose, throat, and skin irritation;
• dizziness and nausea; and
• inability to concentrate, short-term memory loss and hyperactivity.

All of these symptoms, however, may also be caused by other factors, and are not necessarily due to air quality deficiencies. Environmental stressors su ch as improper lighting, noise, vibration, overcrowding, poor ergonomics, and psychosocial problems (such as job or home stress) can produce symptoms that are similar to those associated with poor air quality, but require different solutions.

If these symptoms appear in school occupants, it is important that a physician be consulted to conduct a medical assessment and determine the causes.

Because of varying sensitivity among people, one individual may react to a particular IAQ problem while the surrounding occupants do not experience ill effects. In other cases, complaints may be widespread. In addition to different degrees of reaction, an indoor air pollutant or problem can trigger different types of reactions in different people.

Groups that may be particularly susceptible to indoor air contaminants include, but are not limited to:

• children;
• individuals with allergies or asthma, or people with sensitivity to chemicals;
• people with a respiratory disease;
• people whose immune systems are suppressed due to radiation therapy, chemotherapy, or disease;
• individuals who wear contact lenses; and people with pre-existing medical or psychosocial problems (such as job stress.)

Six Basic Control Strategies

There are six basic control methods for lowering the concentrations of indoor air pollutants and minimizing the exposure of school occupants. Specific applications of these basic control strategies are noted in the IAQ Action Kit checklists.

1. Source Management includes source removal, source substitution, and source isolation. Source management is the most effective control method since it addresses one of the basic causes of IAQ problems.
   
   
   • Source removal is a very effective measure, and school employees should always be alert for opportunities to remove contaminant sources. Policies and actions that keep potential pollutants from entering the school are even better at preventing IAQ problems. Examples of source removal include not allowing buses to idle near outdoor air intakes (check to see what your municipal guidelines are), keeping garbage out of rooms, and banning smoking within the school.
   • Source substitution involves the review of activities with the goal of replacing components/procedures with ones that reduce or eliminate air contaminants. Source substitution includes actions such as selecting a less toxic art material than products that are currently in use, using interior paint with low chemical emissions or replacing pressed wood cabinets with sealed or laminated surfaces.
   • Source isolation involves placing a barrier around the source so that it releases fewer pollutants into the indoor air. Examples include asbestos control measures, or conducting activities that produce contaminants only in properly designed areas
     
     
2. Local Exhaust involves the removal of point (single) sources of pollutants before they can disperse into the indoor air, by blowing the contaminated air directly outside. Sites where local exhaust is used include restrooms and kitchens. Other locations where pollutants originate at specific points and can be easily exhausted include science labs and housekeeping storage rooms, printing and duplicating rooms, and vocational/ industrial areas such as welding booths.
   
   
3. Ventilation introduces cleaner outdoor air into the building to dilute polluted indoor air. Generally, local building codes specify the quantity (and sometimes quality) of outdoor air that must be continuously supplied to an occupied area. For activities such as painting, or in the event of chemical spills, a temporary increase in ventilation can help to dilute the concentration of noxious fumes in the air. Ventilation should not be considered as a substitute for proper work practices and other measures that eliminate or control the original source of the pollutants. Ventilation is most efficient and effective when applied to a well-designed and managed facility.
   
   
4. Exposure Control includes adjusting the time and location of use in order to minimize the exposure of school occupants to intentionally released air contaminants. For example, the best time for stripping and waxing floors is on Friday after school is dismissed. This schedule would allow the floor products to off-gas over the weekend, reducing the level of odours or contaminants in the air when the school is occupied. To remove odours over the weekend, the ventilation system should be left operating with the outdoor air intakes open. Extending or altering how long the ventilation system operates can reduce people's exposure to airborne pollutants. Adjusting the location of use involves moving the contaminating source as far as possible from school occupants, or relocating susceptible occupants.
   
   
5. Air Cleaning usually involves the filtration of particles from the air as it passes through the ventilation equipment. Gaseous contaminants can also be removed, but in most cases this type of system is complex and expensive and should be evaluated on a case-by-case basis.
   
   
6. Education of the school occupants regarding IAQ is critical. People must be provided with information about the sources and effects of contaminants (including those under their control), and about the proper operation of the ventilation system. With this knowledge, they will better understand their indoor environment and can take steps to reduce their personal exposure and improve the overall IAQ in the school.

Your Role in the IAQ Team

As one of the people occupying a school, your activities and decisions have an impact on the quality of indoor air. You can help to ensure the school provides the best possible air quality by applying the knowledge in this chapter and using the checklists that follow.

The IAQ Action Kit includes checklists for the following systems and school areas:

• Administrative
• Health
• Air Handling
• Classroom
• Relocatable Classroom
• Building Maintenance
• Custodial
• Food Service
• Waste Management
• Renovation and Repair
• Design/Build/Lease-Back Facilities

What are the Signs of an IAQ Problem?

IAQ problems may be present if school occupants experience specific symptoms or if there are facility-based indicators that suggest potential problems.

Occupant Symptoms

Diagnosing symptoms that relate to IAQ is complex. Acute (short-term) symptoms of IAQ problems are usually similar to symptoms from colds, allergies, fatigue, or the flu.

Potential signs that may indicate an IAQ problem include:

• The symptoms are widespread within a class or within the school.
• The symptoms disappear when the students or staff leave the school building for a day.
• The onset of symptoms is sudden after some change at school, such as painting, roof repairs, or renovation.
• Persons with allergies, asthma, or chemical sensitivities have reactions indoors but not outdoors.
• A doctor has found that a student or staff member has an indoor air-related illness.

Facility-Based Indicators

Sometimes, there are facility-based indicators of IAQ problems in a school. Some clues that may point to a potential air quality problem include:

• facility-related problems such as visual or physical evidence of water entry or damage, odours, maintenance or custodial deficiencies, a history of problems, or other "good practice" issues;
• building use that is inappropriate for the design, such as unvented kilns or laminators, the use of high contaminant sources in normal classrooms, storage of large amounts of materials or materials of unknown quality, or overcrowding.

There needs to b e programs in place to control those contaminants which may cause long-term health effects but do not tend to cause short-term irritant effects. Management plans should be in place to control contaminants such as asbestos and radon. These plans would normally be separate from an IAQ strategy, and would include periodic inspections.

What if You Suspect an IAQ Problem?

Successful IAQ management requires the development and use of a systematic approach. If you receive complaints that seem to indicate a potential IAQ problem, and the problem is self-evident, try to correct the problem at the school level. If the problem cannot be corrected, or if the complaint seems to indicate a potentially severe IAQ problem, you should contact the IAQ coordinator immediately. Some problems may require professional assistance. Actions should be timely, thorough, and followed up to ensure the problem is resolved. Keep a complete written record of all the actions that you take.

Communication

Indoor air quality problems can jeopardize the health of students and staff, therefore parents and the public may react strongly to reports of bad indoor air quality in a school. It is recommended that follow-up actions be taken quickly and that the IAQ team follow communications guidelines established by the IAQ coordinator. Usually, this will involve referring questions from the public and media to one central source, the IAQ coordinator. In this way, students, parents, staff, and the public will not be confused by conflicting or inaccurate information, and will have a consistent and complete source of information regarding the quality of indoor air in the school