The quality of air inside the schoolhouses of America may have a profound effect on students' ability to concentrate on their lessons. The environmental hazards that influence the quality of the indoor air (IAQ) of our schools have not been well understood. Research evidence suggests that school age children and youth (especially those under the age of 10) exposed to the types of contaminants found inside some buildings are especially vulnerable and at a greater health risk than the adult population. A brief historic review of IAQ includes a discussion of the Clean Air Act of 1970, conservation measures of the early 1970s, and the new types of particles and gases introduced into the indoor air over the last few decades. Some children, those pre-school age to age 10 and special education students, may have health characteristics that compound their risk. Some of the children's unique susceptibilities include (1) developing organs and systems; (2) low immune competency; (3) fragile central nervous systems; (4) immature liver and kidneys; (5) retention of toxins for long periods; (6) skin sensitive to inhaling, ingesting, and absorbing pollutants; and (7) possibly greater exposure to certain hazards. Appended are seven references. (SI)