Indoor Air Quality Backgrounder: The Basics I ndoor air quality (IAQ) is an Failure to prevent or respond promptly to increasingly important issue in schools IAQ problems can: across the nation. IAQ can directly affect • Increase potential for long- and short- the health and comfort of students and term health problems for students and staff. There are many ways that school staff. occupants can help to improve air quality. EPA developed the Indoor Air • Negatively impact student attendance, Quality Tools for Schools (IAQ TfS) comfort, and performance. Program to help schools address many IAQ issues using practical and often • Reduce teacher and staff comfort and performance. low-cost measures (such as unblocking ventilation supply vents to improve • Accelerate deterioration and reduce airflow). efficiency of school facilities and Good IAQ helps to equipment. By simply reviewing this Indoor Air provide a healthy Quality Backgrounder and completing • Increase potential for school closings and productive envi- the IAQ checklists, occupants can learn or relocation of occupants. ronment for students, how to make a significant impact on teachers, and staff IAQ and provide a healthy learning and • Strain relationships among school working environment. administration, parents, and staff. in order to assist a school in its This guidance is based on the • Create negative publicity. following principles: • Impact community trust. core mission— educating children. • Most IAQ problems can be prevented • Create liability problems. and resolved by school staff through simple, inexpensive measures. UNDERSTANDING IAQ • The cost and effort needed to prevent PROBLEMS AND SOLUTIONS most IAQ problems is significantly To understand IAQ problems and less than the cost and effort required solutions, it is important to know what to resolve problems after they factors affect IAQ. These include: develop. • Sources of indoor air pollutants. WHY IAQ IS IMPORTANT TO • Heating, ventilation, and air YOUR SCHOOL conditioning (HVAC) systems. Most people are aware that outdoor • Building occupants. air pollution can impact their health, but indoor air pollution can also have • Pollutant pathways. significant, harmful effects. EPA studies of human exposure to air SOURCES OF INDOOR AIR pollutants indicate that indoor levels of POLLUTANTS pollutants may be two to five times— Indoor air contaminants can originate and occasionally more than 100 times— within the building or be drawn in from higher than outdoor levels. EPA and its outdoors. Air pollutants consist of Science Advisory Board consistently numerous particulates, fibers, mists, rank indoor air pollution among the top bioaerosols, and gases. It is important to five environmental health risks to the control air pollutant sources (see the table public. on the next page), or IAQ problems can This is especially important to schools, arise—even if the HVAC system is as children may be more susceptible to properly operating. air pollutants. 1 of 5 A complicating factor is that indoor air Not all HVAC systems accomplish all of pollutant concentration levels can vary by: these functions. Some buildings rely only on natural ventilation. Others lack • Time (for example, weekly, during floor mechanical cooling equipment, and many stripping); and function with little or no humidity control. • Location (within a school or even The two most common HVAC designs in within a single classroom). schools are unit ventilators and central air- HVAC System Design and handling systems. Both can perform the Operation same HVAC functions, but a unit ventilator serves a single room while a Properly designed HVAC equipment in a central air-handling unit serves multiple school helps to: rooms. • Control temperature and humidity to The diagrams on page 5 of this Indoor Air provide thermal comfort. Quality Backgrounder show how three • Distribute adequate amounts of outdoor typical HVAC designs circulate air air to meet ventilation needs of school through classrooms. As shown in the occupants. diagrams, it is important that all rooms have both an air supply and exhaust. • Isolate and remove odors and pollutants through pressure control, filtration, and exhaust fans. TYPICAL SOURCES OF INDOOR AIR POLLUTANTS Outdoor Sources Building Equipment Components and Other Indoor Furnishings Sources Polluted Outdoor Air HVAC Equipment • Pollen, dust, fungal • Microbiological growth Components • Science laboratory spores in drip pans, ductwork, • Microbiological growth supplies • Industrial emissions coils, and humidifiers on or in soiled or water- • Vocational art supplies • Vehicle emissions • Improper venting of damaged materials • Copy/print areas combustion products Nearby Sources • Dry traps that allow the • Food prep areas • Dust or debris in passage of sewer gas • Loading docks ductwork • Smoking lounges • Materials containing • Cleaning materials • Odors from dumpsters Other Equipment volatile organic • Emissions from trash • Unsanitary debris or • Emissions from office compounds, inorganic building exhausts near equipment (volatile compounds, or damaged • Pesticides outdoor air intakes organic compounds, asbestos • Odors and volatile Underground Sources ozone) • Materials that produce organic compounds • Radon • Emissions from shop, particles (dust) from paint, chalk, • Pesticides lab, and cleaning Furnishings adhesives • Leakage from equipment • Emissions from new • Occupants with underground storage furnishings and communicable diseases tanks floorings • Dry-erase markers and • Microbiological growth similar pens on or in soiled or water- • Insects and other pests damaged furnishings • Personal care products 2 of 5 Building Occupants SIX BASIC CONTROL The effects of IAQ problems on school STRATEGIES occupants—including staff, students, and There are six basic control methods that others—are often non-specific symptoms can lower concentrations of indoor air rather than clearly-defined illnesses. pollutants. Specific applications of these Symptoms commonly attributed to IAQ basic control strategies may be noted in problems include: the attached checklist(s). • Headache, fatigue, and shortness of breath. 1. Source Management - Management of pollutant sources includes: • Sinus congestion, cough, and sneezing. • Source removal - Eliminating • Eye, nose, throat, and skin irritation. pollutant sources or not allowing them • Dizziness and nausea. to enter the school. Examples include not allowing buses to idle, not placing These symptoms could be caused by air garbage in rooms with HVAC quality deficiencies, but may also be equipment, and replacing moldy linked to other factors—poor lighting, materials. stress, noise, and more. Due to varying sensitivities among school occupants, IAQ • Source substitution - Replacing problems may affect a group of people or pollutant sources. Examples include just one individual. In addition, IAQ selecting less- or non-toxic art problems may affect people in different materials or interior paints. ways. Individuals that may be particularly • Source encapsulation - Placing a susceptible to effects of indoor air barrier around the source so that it contaminants include, but are not limited releases fewer pollutants into the to, people with: indoor air. Examples include covering • Asthma, allergies, or chemical pressed wood cabinetry with sealed or sensitivities. laminated surfaces or using plastic sheeting to contain contaminants when • Respiratory diseases. renovating. • Suppressed immune systems (due to 2. Local Exhaust - Removing point sources radiation, chemotherapy, or disease). of indoor pollutants (through exhausting • Contact lenses. fume hoods and local exhaust fans to the outside) before they disperse. Examples Pollutant Pathways and include exhaust systems for restrooms and Driving Forces kitchens, science labs, storage rooms, Airflow patterns in buildings are printing and duplicating rooms, and determined by the combined forces of vocational/industrial areas (such as welding mechanical ventilation systems, human booths and firing kilns). activity, and natural effects. Air pressure 3. Ventilation - Lowering pollutant differences created by these forces move concentrations by using cleaner (outdoor) airborne pollutants from areas of higher air to dilute polluted (indoor) air. Local pressure to areas of lower pressure building codes likely specify the quantity through any available openings in building (and sometimes quality) of outdoor air that walls, ceilings, floors, doors, windows, should be continuously supplied in your and HVAC systems. For instance, as long school, as do voluntary standards set by the as the opening to an inflated balloon is American Society of Heating, kept shut, no air will flow. When opened, Regrigerating, and Air-Conditioning however, air will move from the inside Engineers (ASHRAE). Temporarily (area of higher pressure) to the outside increasing ventilation coupled with proper (area of lower pressure). use of the exhaust system while painting or Even if the opening is small, air will move applying pesticides, for example, can be until the inside pressure is equal to the useful in diluting the concentration of outside pressure. noxious fumes in the air. 3 of 5 4. Exposure Control - Adjusting the time and • Symptoms are widespread within a IAQ Checklists location of pollutant exposure. An example class or school. Available of time control is scheduling floor stripping • Symptoms disappear when the and waxing (with the ventilation system • Teacher’s students or staff leave