EARLIER: According to a computer model that studies air quality, students at about one-quarter of the nation's school were being exposed to higher levels of industrial pollution in 2005 than they were 10 years ago, USA Today says. Using the government's most up-to-date model for tracking toxic chemicals, the newspaper spent eight months examining the impact of industrial pollution on the air outside schools across the nation. The model is a computer simulation that predicts the path of toxic chemicals released by thousands of companies. The result: a ranking of 127,800 public, private and parochial schools based on the concentrations and health hazards of chemicals likely to be in the air outside. The model's most recent version used emissions reports filed by 20,000 industrial sites in 2005.