(HealthDayNews) -- Twenty percent of the U.S. population, nearly 55 million people, spend their days in elementary and secondary schools. Studies show that one-half of the nation's 115,000 schools have problems linked to indoor air quality, the Environmental Protection Agency reports.
Students are at greater risk because of the hours spent in school facilities and because children are especially susceptible to pollutants, the EPA says.
The three major sources of indoor air problems in schools are building maintenance, waste management and food service.
