This fact sheet details important information on Indoor Air Quality (IAQ) in school buildings, problems associated with IAQ, and various prevention and problem-solving strategies. Most people spend 90 percent of their time indoors, therefore the Environmental Protection Agency ranks IAQ in the top four environmental risks to the public. The consequences surrounding poor IAQ affect not only the health and productivity of students and staff but also the physical school plant. Four factors affecting IAQ are: sources of indoor pollutants; the heating, ventilation, and air conditioning systems (HVAC); pollutant pathways; and the building occupants. Six basic control strategies for lowering concentrations of indoor air pollutants include (1) removing, substituting, and encapsulating the source; (2) the effective use of local exhaust; (3) ventilation to dilute contaminated air; (4) exposure control using the principles of time and location use; (5) cleaning the air by filtration; and (6) education to help reduce personal exposure. Diagnosing indoor air quality problems involves identifying short-term symptoms typically associated with colds, flu, and allergies. Long-term symptoms such as cancer are more difficult to identify. Preventive indoor air programs need to be established to minimize students and staff exposure to pollutants. This fact sheet makes reference to an "EPA Indoor Air Quality Tools for Schools Kit" (which includes a checklist, guide, problem-solving wheel, fact sheet, sample memo, and sample policies) and recommends obtaining the kit in the event symptoms of indoor air pollutants related to the school environment are experienced. (RE)